Runing high head pressure!

[todouble]

Ive got a Copeland C8AJ0200CAV001 condensing unit and its conected to an existing Treton evap coil. We replaced the condenser with a new one, changing the txv, drier, and sightglass. We've done over 100 of these that we have all over the area and this one for some odd reason is running high head pressure and tripping out. Existing unit was a R-12 with AB oil and the new one is R-22 with POE oil. The condenser fans are turning up to speed and in the right direction, the coils are brand new, the refrigerant charge is correct, we got the vacumn down to 200 microns on the original install and put in virgin refrigerant. Thoughts of non-condensables in there, so we removed refrigerant, changed drier again and installed again new virgin refrigerant. Suction is running high as well. We are looking for a 40 degree evap, the space is cool (75 degrees). There is an identical unit right next to this one that is running normal with the same refrigerant and same amount in it. Doesnt make sense, any ideas???

[genesis]

Whats the super heat? Sounds like a bad head on the TXV if you have identical units if you have ruled out a restriction

[jim2005]

Yes what is the super heat and what is the sub-cooling. Are you sure it is not overcharged. Are you stacking refrigerant.
If it is overcharged and has a liquid restriction you will see high head pressure.
I tell my guys to do a start up sheet on the equipment and after they gather all not just some of the needed info, they find the problem right away.

Good luck

[cy]

are you sure existing evaporator coils are completely clean?


Ive got a Copeland C8AJ0200CAV001 condensing unit and its conected to an existing Treton evap coil.

[icemeister]

Is it tripping out on the high pressure control or the overload protection?

What were the suction & discharge pressures, the box temperature and the ambient temperature when it tripped?

At a 40ºF evaporator temp and 90ºF ambient, this unit should run close to 300 psig discharge pressure. If your evap temp and/or the ambient is much higher you can get to the trip point real easy.

[todouble]

Generally restrictions give me low suction and thats what has me hungup. I have higher suction than normal, along with my high head pressure as if theres a huge load to work with. But the space temp is normal at 75 degrees. Ive replaced the txv and drier again and still have same problem. The evap and cond coils are squeaky clean and were positive the charge is right. On the original startup which I completely myself things were running excellent and everything was normal. This problem just came about wirh some higher than normal ambient condition were having right now. But again I gave the same unit about 1 year older running right next to it just fine.

[todouble]

Also I cant keep the thing running long enough to even capture a stabilized superheat or subcooling reading. Anythibg internal to the compressor that would cause this. Bad discharge valves maybe?? I dont know much about the internal parts, but it is a semi-hermetic so we can tear apart some things.

[todouble]

Pressures are 100/375 then it cuts out. Only runs for maybe 5-10 seconds then trips hp ctrl. Box temp is at 75 degrees which is the normal setpoint.

[3rdgenhvac]

How many microns did you pull it down to???

Sounds like non-condensibles to me.

[3rdgenhvac]

sry, i just read your whole first entry, u should have no problem @ 200 microns

Probly just the initial load w/ the hot day.

[jim2005]

If it wont run long enough to check it out have you tried using water over the condenser coil or removing some of the gas.
I would fist try the water if you are certain about the charge.
And
Does this have a headmaster?

[icemeister]

Pressures are 100/375 then it cuts out. Only runs for maybe 5-10 seconds then trips hp ctrl. Box temp is at 75 degrees which is the normal setpoint.

That condition puts you solidly outside the operating envelope for this unit. That's why it's tripping out on you.....it's overloaded.

You need to add a CPR valve and set it either to the RLA of the compressor or to about 76 psig which will limit your suction to an equivalent 45ºF evap...which is where this puppy tops out.

[todouble]

We have been installing these things since 1995 and have installed over 250 of these units and none of them have cpr valves. Every other one runs just fine and this particular one is not any different tha the rest of them.

[hands]

Did you make sure the discharge service valve on the compressor is fully open?

[todouble]

Yes discharge, liquid line, and suction valves are open.

[icemeister]

We have been installing these things since 1995 and have installed over 250 of these units and none of them have cpr valves. Every other one runs just fine and this particular one is not any different tha the rest of them.

Then all I can say is that there is something about this particular system that is different from the 250 others.

From the info you gave, this unit is doing exactly what it should do at those conditions.

You have to limit the suction loading on this unit to prevent the overload trips. Perhaps all of the other system you speak of have undersized TEV's?

I dunno, I'm just going on what's given here.

[icemeister]

My only suggestion other than the CPR is to double-check that TEV to see if it's doing what it's supposed to do.

The compressor appears to be OK to me.

[jackt]

Whats your compressor amperage look like? I know this sounds stupid but, have you rechecked the compressor model number to be sure its the correct compressor for your application? It sounds like you have covered everything else. Its very rare but I have seen units come from factories with wrong compressors. It sounds like you just may not have enough HP for the amount of btu/hr

[todouble]

Well I may have to give it a shot and install a cpr valve. At this point im not sure what else to do. I have to take care of the problem for my customer, so I cant just walk away at this point. Copeland tech support doesnt answer phones or return calls either. Got word that they may be sending my call to India anyway!! Thanks for all the help, I appreciate it!! And yes I have ran the compressor numbers with the condensing unit numbers and they match up. Thanks though...

[superandy]

There may be a problem with the manufacturing of this condensing unit such as a blockage on the discharge line. Can you check the pressure on the liquid line to see if there is a huge difference between there and the compressor discharge?

[shifferbrains]

I recently worked on two reach in refrigerators in a commercial kitchen. I repaired leaks and recharged both of them. I liquid charged to the exact charge listed on the nameplates. Both units came up with a short charge. I ended up adding quite a bit more refrigerant to both units and trimmed the charge by superheat. After a little investigating I found out that someone had replaced both condensing units and evaporators so therefore the listed charge was no longer valid.

In your case I think I would pull out some of the charge to bring the high and low pressures to or near what they should be and check the superheat and subcooling. Who knows...... It might be just what it looks like (system overcharge).

[desertdweller]

Pressures sound like an overcharged unit. Yes I read that you have one right next to it with the same charge. Recover some gas until you can keep it online long enough to get your SH and SC readings and go from there.

[icemeister]

Well I may have to give it a shot and install a cpr valve. At this point im not sure what else to do. I have to take care of the problem for my customer, so I cant just walk away at this point....

When you order the CPR, be sure to get the 30-110 psi range and not the 0-60.

If you're still unsure that the CPR will solve your problem, here's a suggestion.

Throttle down on the compressor by frontseating the suction service valve, back off about 1/4-1/2 turn, start the system and regulate the suction to 70-75 psig compressor suction pressure using the service valve like a CPR.

The compressor will not trip on overload protection this time. ;)

[ozone drone]

You said you had high suction pressure, yet the space was 75 degrees.... How about return air temperature? could it be mixing with air in an attic space causing a high load? Is the return ducting un-insulated in the attic?

[Airmechanical]

There may be a problem with the manufacturing of this condensing unit such as a blockage on the discharge line.

if that was the case he would not have the high suction pressure that he has!



.

[Airmechanical]

are you sure existing evaporator coils are completely clean?

if the evap was not clean, don't ya think the pressures would be lower instead of higher!



.

[beenthere]

Pressures are 100/375 then it cuts out. Only runs for maybe 5-10 seconds then trips hp ctrl. Box temp is at 75 degrees which is the normal setpoint.
How is it maintaining normal box temp, if its cutting out on HP before the pressures equalize.

Remove about 10% of charge and then check.
SH at the compressor, and SC before the receiver.

[soonera/c]

Sounds either overcharged or bad TXV. Your high suction is what's causing the high head. Get your suction down and your head will go with it.

[powell]

todouble,

Just out of curiosity, are these units used to cool the underground switching rooms for ATT or other communication companies?

Also, the C8AJ-0200-CAV-001 comes from Copeland with nothing but a dual pressure control, no low ambient controls or cchtr. Do the units you install have these optional controls installed?

If the either answer is yes then there might be a something you can check.

Powell

[todouble]

Yes Powell they are from underground switch gear room for att. We add the cc htr and the p70aa-118 fan cycling ctrl for low ambient. Ive installed a cpr valve today on this particular one and got things running but after awhile of running things still trip out.

[jackt]

It looks to me that you have a lot of experience in HVAC and have covered all the basics. You pulled a real good vacuum check every thing possible. I still wonder about not having enough HP for the amount of btu/hr that you are trying to remove. The cpr valve may stop the compressor from tripping out on high head but, it most likely won't help your evap load.

[icemeister]

Check out the attached performance data summary from Copeland on this unit.

At +45F Suction and 90F Ambient this unit should run at 130F condensing temperature or around 300 psig. Is the CPR set at 70-75#? What's the ambient? What pressure is it tripping at?

There's been a lot of speculation that this system is overcharged. This unit is short on condenser size (per its design) but fairly generous for receiver capacity, which is 19.8 lbs R22 at 80% full.

To overcharge this system, you would have to fill the receivers (there's two in parallel) to 100% before liquid would stack in the condenser and cause any significant discharge pressure increase. 100% full would be approximately 25 lbs of R22. If you add the amount in the lines and the evaporator you'd have to have well over 30 lbs of juice in this little 2-ton system to be overcharged. To clear the SG and be fully charged, this system should only take 10-15 lbs tops.

How much refrigerant is in there?

[todouble]

Icemaster, we have 12 lbs in the system and this is the point where the sight glass clears, maybe a slight bubble here and there. But if we add anymore its off on hp in a matter of 5 seconds. Adding more gas doesnt help us.

[icemeister]

Icemaster, we have 12 lbs in the system and this is the point where the sight glass clears, maybe a slight bubble here and there. But if we add anymore its off on hp in a matter of 5 seconds. Adding more gas doesnt help us.

Like I said, this system should take about 10-15 lbs to clear the glass. So it's definitely not overcharged. ;)

What about my questions?...



Check out the attached performance data summary from Copeland on this unit.

At +45F Suction and 90F Ambient this unit should run at 130F condensing temperature or around 300 psig. Is the CPR set at 70-75#? What's the ambient? What pressure is it tripping at?

[todouble]

the cpr is set to 65, hp ctrl set to 395, and our ambient air is 97. If I increase the pressure on the cpr to 70 or 75 it drives the head pressure up and I again go off on hp within a couple mins.

[icemeister]

I'll put aside my opinion that this unit never should have been rated for high temperature applications by Copeland because the condenser simply doesn't have the capacity to keep the TD to an more commercially acceptable range like 20º-30º at 45º evap temps. :rolleyes:

Looking at that performance chart again, if we extrapolate it a bit for your 97ºF ambient...let's call it 100ºF for simplicity...I would then expect at a 45ºF evap temp you should be seeing 140ºF condensing temps or around 340 psig.

From what you say, if you set the CPR to 45ºF evap you're getting up to near 400 psig or approximately 155ºF condensing.

Something is amiss in the condenser performance here.

We have ruled out overcharge, so all I can surmise is that there is a possible airflow problem, condenser air recirculation or even a restricted condenser circuit that is causing TD to be 15ºF higher than design.

If the airflow is OK and you can rule out recirculation then I would look into the condenser circuiting and how it appears to be performing. If it has two or three circuits coming into the outlet header, compare the temperatures of these circuits just before they enter the outlet header. It may point to a blocked or restricted circuit.

Also, if as you have stated earlier, that you have an identical unit on site, check the pressure drop between the compressor discharge and the receiver outlet on both units and see if the troubled unit has a higher drop through the condenser as would be expected if one circuit were plugged.

[Slatts]

I remember a system some 20 years ago in which the tubes in the condenser weren't expanded into the fins in the factory. The upshot was bugger all heat transfer in the condenser. High head and back pressure.

[icemeister]

I believe this is an AT&T underground station. I saw their trucks there the other day.

http://i92.photobucket.com/albums/l1/icemeister/071908pics004.jpg

Pretty basic 1 1/2 ton R22 Rheem....just installed a few weeks ago.

http://i92.photobucket.com/albums/l1/icemeister/071908pics006.jpg

[gwoner]

You say the coils are clean, don't assume they're clean. Did you clean them yourself? Never assume just by visual inspection. If they're new, maybe they didn't get all the water out of them at the factory when they were pressure tested.

[jackt]

I still believe you need to go back and recalculate your load and see if you have a big enough system for the load you may be seeing. Also don't forget to figure in your ambient temperature with your load temperature. I've been following all your logs and you have obviously covered almost everything else. I don't believe a CPR valve will help your conditions what so ever.

[drivewizard]

Sorry if I am way off base here, but wife is bugging me to leave for a party.
Only read the first couple posts, have you checked your cond coil circuiting?
Check all return bends, make sure you are using all of the coil.
Somebody may have screwed up at the factory and got some of the
return bends on wrong, eliminating part of the coil.
I found that on a walk-in evap coil on time, had been that way for about 15 years. Owner said it never really got that cold and ran all the time.
He was very happy when I got the other 1/3 of his coil working.

If somebody already mentioned this, then never mind. Gotta go, got beer to drink. :D

[JRINJAX]

Things I would look at: The liquid line approach temp compared to the OAT. If the approach is high[+15] or very low [+2 or less], check the circuiting on the condenser coil.

I would also check the deltaT on the condenser air.

Is there an ORIT valve on the condenser coil?

We service a lot of the SBC/AT&T CVs and SLCs.

[cy]

seems you've already verified system is not overcharged by weighting the charge. have not read this entire thread... so someone may have already mentioned this...

have you checked static pressures before and after the evaporator to verify coils are not plugged up?

[jackt]

I believe you would see the opposite effect if your evap. coil wasn't clean. Lack of air through the evap. coil usually will cause low suction pressure.

[Slatts]

Just thinking about it, if it's only running for 10 or 15 seconds, it won't have time to bring the suction pressure down anyway.
I'd be tempted to decant the system, run a new discharge line from the compressor to the condenser on the off chance that there's a blockage of some sort and blow back from the outlet of the condenser before connecting the new discharge line to make sure it's not restricted.
Desperate times call for desperate measures.:eek:
If that doesn't fix it, I'd put a temperature sensor on the inlet of each pass on the condenser to see if one wasn't heating up.
much like what drivewizard said
Good luck

[jackt]

I don't believe there's any restrictions in the discharge line. This would most likely starve the TXV causing lower suction pressure. You even have a dirty condenser, bad cond. fan motor, motor not turning in the right direction, wrong c fan blade or the system can't handle your load. What does it look like early in the morning before the ambient temperature gets real high? Have you checked the compressor loaded amps? Is the amperage draw way over the RLA? Can you slow down the evaporator fan motor to reduce the load on the evap coil just to see if you can keep it running?

[icemeister]

Back in post #36 I said....


Also, if as you have stated earlier, that you have an identical unit on site, check the pressure drop between the compressor discharge and the receiver outlet on both units and see if the troubled unit has a higher drop through the condenser as would be expected if one circuit were plugged.


I really think there's something different about this particular unit that is causing the higher-than-expected discharge pressures.

I'm betting on a blocked condenser circuit.

[Slatts]

Generally restrictions give me low suction and thats what has me hungup. I have higher suction than normal, along with my high head pressure as if theres a huge load to work with. But the space temp is normal at 75 degrees. Ive replaced the txv and drier again and still have same problem. The evap and cond coils are squeaky clean and were positive the charge is right. On the original startup which I completely myself things were running excellent and everything was normal. This problem just came about wirh some higher than normal ambient condition were having right now. But again I gave the same unit about 1 year older running right next to it just fine.
I didn't notice this bit till now. What do you think would be the affect of breaking a discharge reed or some similar part in the high side of the compressor and having that bit of reed or whatever pumped out into the discharge line?
Have you ever pulled the service valve off a dead compressor and found a piece of broken discharge reed stuck in it?
Seems to me everything is happening to quickly for it to be load related.

Pressures are 100/375 then it cuts out. Only runs for maybe 5-10 seconds then trips hp ctrl. Box temp is at 75 degrees which is the normal setpoint.

[Darylbnet]

x

[Darylbnet]

? I am having the same type problem with a unit, did you find what was causing the problem...tks...D.:confused:

[Kraeusen]

Are there any defrost heating elements in this evaporator? If yes, are they energized?

[Will0351]

Clean the evap if dirty and check txv for proper ops.

[Freezeking2000]

I think someone forgot to install the correct piston on the txv outlet. Still has the r12 piston and you need the correct r22 piston.

[beenthere]

Hopefully, after a month now, he has it fixed.

[Darylbnet]

Yes, I would think so, I hate when they don't come back and let you know the results... I found my problem to be, what seemed to be an overcharge, after bleeding off the Low side down to 85psig it would run without over topping after bringing it down some more, it ran 58L/300H, still don't like the high side. After running 12hrs cycle of 73 to 70 room cycle, woke this morning to find the contact still pulled in, but compressor was not running, so looks like I have more problems to deal with today...D.:cool::confused:

[Darylbnet]

I am not an ac tech, our onboard tech had to go home, so I am stuck in a jam to get this ac unit smoothed back out...
Unit info: Carlyle SRH582AC01 ( 58,400btu ) the following is the closest model I could find for specs, it is 6 years old... Has new dryer/expv/sight/ and water cooling flow is good... Unit is charged with R22
http://www.carlylecompressor.com/Files/Carlyle_Compressor/Local/US-en/scroll_specification_documents/X-Models_R-22_H_460-3-60.pdf

We have been running this unit for a while up north with cooler condensing water, 60deg, now traveling back south the cooling water temp has risen to 74deg, and the unit starts tripping on high head that is the only change to begin with. So we try adjusting the flow rate of the cooling water but no joy, so we think the unit may have gotten too low on freon, but the system didn't take much if any at all on the suction side, I have no scale to measure, so I am in the dark there... Also I am not seeing any liquid on the sight glass, that is what also made me think that it was low. The unit would start and run for about 5 -10 minutes and then trip out on the high side.
So after reading some posts online, seen that most believe that it is overcharged, after bleeding the low side down some, was able to get the unit to run at L 58psi/ H 300psi, as it ran the low side dropped to 45 and it started to take off on the high side up to 380 but all of a sudden it started to regulate itself and the high side came back down to 300 with the low at approx 48psi... So after getting the temp setting straight again, we let the unit cycle 71 to 73deg room temp through the night, it worked up until morning and overheated, the contact was still pulled in but the compressor was not working... I let the unit cool down for 2.5 hrs and restarted it. Upon start up it had 55L/260H, it ran there a few minutes and then the high side eased up to 300 as the Low is slowly coming down to 50, the room temp was up to 78deg so it was going to take a while to get it back down to the desired operating area 73deg. I monitored the unit, and as the low side gets to 48psi the unit would start to go up on the high side and trip out... When the unit cuts out it goes to 85L/150H as the Low side starts to rise up to 115psi as it warms up...
Output air gets all the way down to 40/45deg, could the expv be freezing up??? Could the unit still be over charged...???:confused:
ANY Ideas would be a help?...Thanks...D...:cool:

[cretan]

If its tripping on high pressure and there is no refrigerant in the sight glass,could be a plugged filter drier.moisture in the system freezing the valve.A blocked txv will show low suction pressure.Is it a scroll compressor?

[JRINJAX]

Sounds like a bad powerhead on the TXV. What is the temperature of the liquid line coming out of the condenser?

[Darylbnet]

Yes it is a scroll, similar to the one in the link... Yes looks to be something wrong with the expv, but the glass is true blue so it shows no moisture inline... Can that valve work intermittently, and not just go completely bad...
That is why I have add a little r22 back to it to try and keep the low side from dropping below 50, and is working so far, but high side still at 300...
What can I do to bring the high side back down, if anything...
In the past when the tech has added freon, we could watch the liquid in the glass as we added, now nothing is there, on start or cut off... Thanks...D...:cool:

[beenthere]

Well, in the past, the freon the tech added covered up the real problem.

Now you get to find the real problem and correct it.

Did you measure SH, SC.
Entering and leaving water temps.

What is your GPM to the condenser.

Did you change out the LLFD when you opened the system to change out the TXV.

[Darylbnet]

While running the liquid line from high side is 210 to 220deg into water cool condenser with 77 to 79deg water, output liquid line is 78 to 80deg... I have the unit cycling higher now at 71.1 to 73.9 on tstat so that it doesn't have to cool as long, it puts out 40deg output air and cycles up to 63deg before restart...
On the head itself it comes up from 140deg off state to 235deg high side from my temp gun... Could the compressor itself be getting ready to go out...
Thanks...D...:cool:

[beenthere]

Without operating info. No one can tell.

Vapor pressure and SH, Liquid line pressure and SC, entering water temp, leaving water temp. GPM of water.

Don't use a temp gun, they are not accurate enough.

[Darylbnet]

I have pulled some temps and came up with the following:
Liquid line to txv=78deg, suction line pressure 58psi, and saturation temp 34deg for R22 ( 78 - 34 = 44 SH )...
and
Service valve line = 220deg, High Pressure= 300psi, and saturation temp 132deg to give ( 220 -132 = 88 SC )...
Do these figures look correct...
I will reverify the temps with a temp stick instead of the gun...D...:cool:

[beenthere]

Thats not how you take SH,

What is the suction(vapor) line temp.
What is the liquid line temp, right after the condenser coil.
Still need entering and leaving water temps.
Is there a temp drop across the LLFD.

[Darylbnet]

Thats not how you take SH,

What is the suction(vapor) line temp.
What is the liquid line temp, right after the condenser coil.
Still need entering and leaving water temps.
Is there a temp drop across the LLFD.

Suction Line Temp 57.0F
Liquid line Temp, after cond coil 80.4
Entering water 82.8 and leaving water 82.8
Drop across Liq Line Filter/Dryer is none
at 80.4 on both sides...D...:cool:

[Darylbnet]

Thanks for the help knocking off for today, there is an adjustable exv so we may look into that tommorrow...D...

[beenthere]

Your SH is high.
Your SC is high.
And your water temp has no difference.

Good chance your system is over charged.
The TXV's power head may have lost its charge. And all these times the tech added gas, to cover it up, has now resulted in the high head your seeing.
The TXV may have a strainer that is clogged.

Taking these readings on units, before just adding gas, saves a lot of trouble down the raod.

[Darylbnet]

Awoke, this morning to find it overheated again... going to try and adjust the expv... To me the unit shouldn't have to cool so much down to 40deg output air to cool the room constantly, looking to raise that temp to 55 to 60 deg output air, which will make the unit have to cycle more but hope it will bring down the high side as well...D...:cool::confused:

[beenthere]

Maybe you should verify air flow.
Verify it in CFM, not just it blows a lot of air.

[Darylbnet]

Okay, Like I said as I figured it overheated again this am... Don't really know why, the cycle should have given it plenty of time to cool. Running from 71.1 to 73.9, the unit would cut off for about 20 min allowing the head to cool from 230deg down to 140deg, but after it kicks back on, the temp would rise rapidly to 210 and rise more from there...
I put my temp stick on the line right after the TXV and it had a temp of 63.5 and pretty much stayed there all the time...
I adjusted the valve CCW, backing it out, as I did this the temp after the TXV never changed and the further I went with it the High side would begin to surge, going from 300 up to 360-380 and then back to 300-320 and it would set a few minutes and then surge again, but it would not go too high as to cut out on HHP.
So I started to adjust the valve CW, inward, and it got to the point that it stopped surging, and then as I continued CW, it would lower the High side just a little to maybe 280 and then it would come right back up to 300-310... As I keep going in this direction it started to get higher on the high side...
So I brought it back CCW, out to the point where I was getting the surge, and then moved it back in to just below the surge point, it seem to stay the lowest on the high side there, around 300psi...
All the time that I was adjusting the valve, the Low Suction Side did not move much from 60 to 61psi, and the Temp at the TXV would sometimes dip to 61deg but would go right back to 63deg.
This system was working for a months time after replacing the LLFD, TXV, and Sight, buy a certified contract tech that we use for years. Everyone asks all the same questions, did you change the txv or fd, no because it was already done just 2 months ago, by a contract tech... General consensus is that the tech covered up problems by putting too much freon in the system... So that would lead me to believe that I should put more freon in just to keep it running for now, until the tech can get back to work on it... But that doesn't add up, I have high head pressure now, and no liquid in the sight, but yet when the tech adds more freon to overcharge it, wouldn't that cause his head pressure to be high as well... The unit is doing its job, in cooling and flows look good, my original thought was that the unit was extremely low on freon, and is working too hard with what it does have...

Here is what I have as the unit starts up... After I let it cool down this morning...
Start unit
58L psi / 220H psi / Suction L Temp 58deg / LLTemp post cond 81deg
62L / 260 / 50.4 81
60L / 285 / 54.3 81
60L / 300 / 55.4 81
Shouldn't that Low side be higher and start to drop progressively as the compressor works, instead of just instantly going to 60psi range and staying there...? Hope the info helps...D...:cool::(

[beenthere]

Doesn't matter that the tech replaced the LLFD earlier.

It may be restricted again.

You most likely have a full sight glass, it just looks empty.

You still don't know your air flow.

You have 24° of SH, and 27°of SC.

You have a restriction.

What is your tech certified for?
Does that mean he knows what he's doing. Or he just passed a test.

Get another company to check it.

[Darylbnet]

Tech was from the following company(Link),
http://www.nanceinternational.com/index.html

And no I haven't asked them to prove thier certs on what they are able to work on... Normally if you contract from one of the top companies in the area, you would get someone who has all the proper qualifications. Yes, this company also trains techincians, and they may be sending trainees out instead, who knows...
I am sure if I ask a tech what he is qualified for, he would tell me what I wanted to hear, and not say that he wasn't qualified to work on the problems and then leave...
...D...:cool:

[beenthere]

Try another company.

[cretan]

Had a simular problem with a freezer.It was on its 3rd compressor.Kept shorting the windings.Was seeing high discharge/suction pressures at start-up and would cut-out on overload.I installed the 3rd compressor it worked fine for a while,then the same thing.The wrong gauge of wire was run to the unit(was a new install).With a long run of wire and the wrong gauge not enough power was getting to the compressor which is not good for an electric motor.The wire was replaced and no problems/high pressures after that.Check the voltage going to the running unit,you have nothing to lose.

[zonemech]

Good point cretan, the NEC states that you can only have a voltage drop of 3% from subpanel feeder to load and 3% from service to subpanel and not to exceed a total of 5% from main service to load.
And this is why...

[cretan]

It was a heck of a lesson to learn.The original compressor went,then a journeyman replaced the second and I installed the third.

[Darylbnet]

Thanks for the advice on the line voltage, checked that side and it is all good. After bleeding down the low side to 60psi (R22=34deg), the unit came down on the high side to 260psi (R22=120deg) from 300psi (R22=131deg), it is cooling with an output line temp of 60deg after the expv. After letting the unit run 12 hrs, the low side came down to 43psi (R22=20deg) and the high side has eased back up to 290 to 300psi, but the line temp at the expv is still at 60 to 61deg, sometimes it will drop down to 40deg line temp at the expv but only for a few minutes, then it pretty much stays at 60degs line temp. I have adjusted the expv but it will not make the temp drop any lower. This is with a output H line temp of 81deg after the condenser, I have no port to check the actual pressure after the condenser output, only on the compressor side before it goes into the water cooled condenser... From what I see the cooling is bringing it from 130deg back down to 81deg, which would make the pressure around 143psi... Question is what should that come down to, in order to provide the proper cooling across the expv...? Is that all I will be able to get on the expv is a drop of 20deg. ? ...D...:cool::confused:

[beenthere]

You generally don't want more then 20°F delta across the evap.
You got troubles.
You still haven't verified water flow GPM.
SC, or SH.

[cretan]

Not sure if this unit is set-up this way,but.Are you taking pressures with access panel off which is pulling air through panel and not the coil?

[leeslone]

yikes you guys are kinda tough....lol

[leeslone]

ok since the subject of high head exists gotta kitchen 93 degrees and climbing two 7.5 ton tranes and both are trashed. Evacuated and recharged both to be sure of charge. Cleaned inside and out. Good split but have heads bout to blow off the roof. Can't believe it. multiple orifice tranes. headers do not show temp difference and I am at a loss.lol give it some thought before you answer.

[leeslone]

yea the covers are in place and the guages work....lol

[leeslone]

replace the txv and wrap the bulb then leave it alone