TRANE UNIT high pressure problem

[LeesService]

Hi, I am new to this forum.
Hopefully it'll be a good place to help each other out.

I have 2 very similar cases with 2 very similar Trane Models.

Model No. YCC060F1M0BJH
SERIAL: 4352M542H

I replaced the compressor bc it was bad.
Now the high side is around 320PSI and low side is around 50psi.
I put in 11.2lbs of r22 as the specifications state.
Im pretty sure something is stopped up.
This unit is at a dry cleaners and is probably around 100 degrees inside. outside temp was around 90 degrees.

I replaced the compressor again and put in just 5 lbs of r22. the high side is now around 280-290psi and low side is still around 50-55psi.
Air coming out is 74 degrees.
I need a place to start.
Any help would be appreciated

[HVAC-matt]

Well the discharge pressure looks pretty good for the OAT that you stated. Could the unit be undersized? You said that it was 100 inside, your temp drop over the coils is more than 20 deg looks pretty good. Is the evap coil clean? What are you SH and SC? How long ago was the compressor replaced the first time? Let us know.

[hvac wiz 79]

are u saying u replaced the compressor twice because your pressure wasn't where u wanted it? .. your lacking info like matt said

[LeesService]

I did not check SC and SH. evap and condensor looks clean.
first compressor was changed 3 days before the second one. second time, we only charged 6.8lbs opposed to 11.2 lbs bc we were afraid it was going to blow again. so right now it is undercharged.

Is there a way to check for restriction in the condensor?

[timebuilder]

I have two questions.

1) Why was the first compressor replaced?

2) Is HVAC you main business?

[dave sulz]

100 deg inside I'd like to see a higher suction press. Is the suction line cold?

[MUNC]

Trane RTU first, split the condesor coil and clean it inside and out. did you replace the filter drier? next subcool!!! Trane has an issue with the distribution headers (Orfices) plugging up. look for frost after orfices. They came out with a new TXV header assembly for some rtu's

[dave sulz]

How do you split the coil?

[flavat75]

I had one today, 2 stage trane rtu 25/300. I cut out the filter drier, and pushed about 40 lbs of nitro through it. I braised new drier in. then unsweat a joint b4 evap manifold and pushed more nitro through both sides. she running awesome now. 18 degree delta T :grin2:

[flavat75]

oh ya used bigger drier. idk whats up with those trane driers. they so small.

[408-COUPE]

evap and condensor looks clean.


Never assume, always confirm. Going off of process of elimination, it sounds like you replaced the first compressor because of the same issue you are having now. Did you blow the lines out with nitrogen before installation? Did you pull a vacuum? Is this your first time working on the unit, if not, has it cooled well before "the compressor went out".

[jimj]

So your on your THIRD compressor? What was the problem with the FIRST one?

[Norriski Tech]

Hello Munc is right the condenser coils are split I believe. How do you split the coils Dave Sulz?. You remove the top, take the screws that hold the tube sheet together out, and split them then clean like crazy. You can't get the charge right until those coils are clean!!. With a 100 degree return temp your suction pressure should be thru the roof. Number one refrigerant rule temperature and pressure go together. Number two what happens to one side, happens to the other under normal conditions. A undersized unit under normal condition's would have high suction, high head due to our number one rule. I think you need to clean some coils and I totally agree with Munc look at the orifice's metering device, carrier had the same issue with that setup. And remember that a bad compressor if it running won't bring the suction down if the valves are bad, suction would be high. The compressor's are not your problem.

[iceman777]

charge with liquid by spec plate, and check superheat. If it is high, there is restriction, most likely in feed orifices. If superheat is through the roof, that can burn up a compressor pretty quick.

[MUNC]

same thing for sub cooling, if those orfices are plugged you'll back that magic juice into the condensor and have excessive subcooling.

[HVAC-matt]

So is this a two stage unit or you are saying you have gone through a compressor in 3 days? Second as others have said you need to charge the unit to specs, or you are going to overheat that new compressor with lack of cooling from the refrigerant. You also need to check all other pressures if you think you may have a restriction and fix it ASAP or you will be replacing that compressor again.

[penguin167]

sounds like the orifice is stopped up, check subcooling. 100f return air would make that suction pressure higher. if you changed the driers, then its the metering device in that unit. Trane orifice's will get plugged up, i'd suggest replacing them with the TXV kit from trane.

[timebuilder]

Has anyone noticed that the OP has not posted back? No response to my questions, or any of the advice offered?

Hmmmmmmmmmm.

[408-COUPE]

Has anyone noticed that the OP has not posted back? No response to my questions, or any of the advice offered?

Hmmmmmmmmmm.

YUP. The truth always seems to scare people off..

[dunkman]

I wonder why parts are so expensive. Maybe has something to do with so many wrecked compressors that didn't need to be.\\

How can you possibly replace a compressor and not check SH and SC?

[lovecoldair]

Sound to me like maybe air in the system and or clogged condenser with an under charge

[btuser]

I have had 3 Trane TSC RTU's with plugged capillary feeding tubes plugged. These units never had the systems opened so how the gunk that got in there is still a mystery. No help from Trane. One of my tech's made a cleaning device out of a real small screw driver and cutting torch cleaning wire to clean these out. Units are running fine.

[CommtechinVA]

I have had 3 Trane TSC RTU's with plugged capillary feeding tubes plugged. These units never had the systems opened so how the gunk that got in there is still a mystery. No help from Trane. One of my tech's made a cleaning device out of a real small screw driver and cutting torch cleaning wire to clean these out. Units are running fine.

It was explained to me that the "gunk" is actually the oil that has been "cooked" due to hi head pressures and temperatures. I've never seen anything from Trane, verifying this, but I do find it interesting that I usually find restricted orifices either after changing a compressor or finding the condenser stopped up and needing cleaning. Just my :.02:

[timebuilder]

Yep. The oil breaks down and makes a varnish.