carrier won't cool Tech wants to replace TXV

[curtbsa]

I have a less than 1 yr old carrier 25HPA536A310. Installed last August. Stopped cooling effectively. Tech came out his notes are: and "Added 3lb 10 oz of R-410a to bring subcool to speed. 11 deg., press 250/48 w/87 deg. sat temp and 74 deg. LL temp. No indication of overheat to TXV buld. TXV is only possibility. 7 deg. split." I know nothing about this, but should this much R-410a need to be added to a new system? It cooled fine last Aug-Sept when installed. I've read other posts here where TXV replacement was more than common. Any ideas what could be wrong? Faulty installation? My warrenty is up in August so I do not want this to be a hunt and peck every month until I'm out of warranty. Any help or direction appreciated.

[HVAC-matt]

I would think that a unit that is less than a year old should not need any refrigerant added. I would question why they needed to add some. Sounds as though you may have a leak in it. The TXV that is less then 1 year old should not need to be replaced. Let us know what they say.

[american]

I have a less than 1 yr old carrier 25HPA536A310. Installed last August. Stopped cooling effectively. Tech came out his notes are: and "Added 3lb 10 oz of R-410a to bring subcool to speed. 11 deg., press 250/48 w/87 deg. sat temp and 74 deg. LL temp. No indication of overheat to TXV buld. TXV is only possibility. 7 deg. split." I know nothing about this, but should this much R-410a need to be added to a new system? It cooled fine last Aug-Sept when installed. I've read other posts here where TXV replacement was more than common. Any ideas what could be wrong? Faulty installation? My warrenty is up in August so I do not want this to be a hunt and peck every month until I'm out of warranty. Any help or direction appreciated.


You should have at least a 5 year warranty on parts. Possibly the installing company gave a one year labor warranty. What was you original service call for? Could be a follow up call maybe.

[2old2rock]

First, I would ask them to send a different tech.
Second, I would ask them to find the leak.

[curtbsa]

I'm no genius, but I know enough to know I shouldn't need almost 4lbs of refrigerant to a unit less than 1 yr old. Parts warranty is 10 years but labor 1 yr. I want it fixed and fixed right, not a hunt and peck and guess. Service company is the same company that installed it and they are supposed to be a reputable established outfit. Ditto on the new tech.

[rselby]

What was the ambient temperature? He didn't calculate superheat, which would have been really nice to know. Shooting from the hip, yes you have a leak and a 7* split (with missing information) could be a TXV, but I'd need more info to be exact.

[Roadhouse]

Since he's recently added some refrigerant R-410A has the system been operating normal, without the replacement of the txv, such as it was in the beginning?

If so then there's no more evidence that would conclude that the txv is bad and/or that your system is NOT leaking.

[Shophound]

I have a less than 1 yr old carrier 25HPA536A310. Installed last August. Stopped cooling effectively. Tech came out his notes are: and "Added 3lb 10 oz of R-410a to bring subcool to speed. 11 deg., press 250/48 w/87 deg. sat temp and 74 deg. LL temp. No indication of overheat to TXV buld. TXV is only possibility. 7 deg. split." I know nothing about this, but should this much R-410a need to be added to a new system? It cooled fine last Aug-Sept when installed. I've read other posts here where TXV replacement was more than common. Any ideas what could be wrong? Faulty installation? My warrenty is up in August so I do not want this to be a hunt and peck every month until I'm out of warranty. Any help or direction appreciated.

The way I'm reading this, your tech used a jug of refrigerant as a diagnostic tool. He put gauges on the system and for all intents and purposes it read as low refrigerant charge. I'm not finger pointing at him. There's not a tech out there who has not ever slapped his gauges on a system, read the pressures, thought low charge, and began charging, only to find he's got a bigger issue. I've been there. You learn.

Without actually being at your house and without knowing what your indoor and outdoor air conditions were at the time your tech checked your system, I would still lean toward his analysis as being correct. A TXV that fails closed starves the evaporator and can lead a tech to think the charge is low. What your tech may want to do in the future is search for obvious signs of refrigerant leakage first, as any system that is actually low on refrigerant has a leak, and that leak must be repaired.

[woody19]

If he added almost 4 pounds of refrig. and the pressures were 250/48 you may have more than one issue. Is that the way he left the system operating?
Was it cooling after he was done? Something isnt jiving here. If that is what pressure he had then the coil will be iced up and you wont get any cooling.
Did he even attempt to look for a leak?
As stated earlier...insist on another tech coming out. If you aren't satisfied call the Carrier hot line and complain. They will contact the area tech support and help you. You paid good money for a good system and you aren't getting good service for what you paid. Just my opinion.

[rselby]

The way I'm reading this, your tech used a jug of refrigerant as a diagnostic tool. He put gauges on the system and for all intents and purposes it read as low refrigerant charge. I'm not finger pointing at him. There's not a tech out there who has not ever slapped his gauges on a system, read the pressures, thought low charge, and began charging, only to find he's got a bigger issue. I've been there. You learn.

Without actually being at your house and without knowing what your indoor and outdoor air conditions were at the time your tech checked your system, I would still lean toward his analysis as being correct. A TXV that fails closed starves the evaporator and can lead a tech to think the charge is low. What your tech may want to do in the future is search for obvious signs of refrigerant leakage first, as any system that is actually low on refrigerant has a leak, and that leak must be repaired.

I agree with your statement, superheat at the evap coil would have been some handy information to know.

[aircooled53]

I have a less than 1 yr old carrier 25HPA536A310. Installed last August. Stopped cooling effectively. Tech came out his notes are: and "Added 3lb 10 oz of R-410a to bring subcool to speed. 11 deg., press 250/48 w/87 deg. sat temp and 74 deg. LL temp. No indication of overheat to TXV buld. TXV is only possibility. 7 deg. split." I know nothing about this, but should this much R-410a need to be added to a new system? It cooled fine last Aug-Sept when installed. I've read other posts here where TXV replacement was more than common. Any ideas what could be wrong? Faulty installation? My warrenty is up in August so I do not want this to be a hunt and peck every month until I'm out of warranty. Any help or direction appreciated.

That is NOT correct pressures for R410a system.

[SoFlaDave]

That is NOT correct pressures for R410a system.

This a billion times, this. Sounds like there may be 2 issues at work here.

[curtbsa]

thanks to everyone for replying. Refrigerent did not solve the problem, won't cool. Tech turned AC off and we only have the fan circulating air in the house. He said if TVX is bad, running unit will damage it. I am waiting on the company to call me back after reviewing tech notes and they are seeing if the TVX part is available in their warehouse/supply and if not, when will one come in. Told them I was concerned about either A- a leak that needs to be fixed or B - did they add too much coolant and damage the system. (don't know if its possible to add too much) They are gettting back with me later this PM.

[LKJoel]

thanks to everyone for replying. Refrigerent did not solve the problem, won't cool. Tech turned AC off and we only have the fan circulating air in the house. He said if TVX is bad, running unit will damage it. I am waiting on the company to call me back after reviewing tech notes and they are seeing if the TVX part is available in their warehouse/supply and if not, when will one come in. Told them I was concerned about either A- a leak that needs to be fixed or B - did they add too much coolant and damage the system. (don't know if its possible to add too much) They are gettting back with me later this PM.

definately possible to add too much refrigerant!!

Replacing the TXV will require removing the entire charge, at that point (if he is on the ball) the tech will weigh the charge removed, and get a good indication of weather or not the system was actually low or not.

once the change-out is complete, he should be weighing the propper charge into the system, making it unlikely to leave your system overcharged.

so at least for that much, you should be okay, as to weather or not the TXV was really the problem, only time will tell (or more information!)

[Dr.phil]

It looks to me that he added refrigerant to confirm his diagnosis of a bad txv. Giving him the benefit of the doubt, the pressures are not right for 410a. The temp split is definitely not right. Again, giving him the benefit of the doubt, I think he's right.

[Kevin O'Neill]

definately possible to add too much refrigerant!!

Replacing the TXV will require removing the entire charge, at that point (if he is on the ball) the tech will weigh the charge removed, and get a good indication of weather or not the system was actually low or not.

once the change-out is complete, he should be weighing the propper charge into the system, making it unlikely to leave your system overcharged.

so at least for that much, you should be okay, as to weather or not the TXV was really the problem, only time will tell (or more information!)

I would not remove the refrigerant. Pump it into the outdoor unit, change the TXV, install a new drier, vacuum the system, open service valves. Start the system and check the charge. Still sounds like a leak. Pressures way low for R-410a.

[LKJoel]

I would not remove the refrigerant. Pump it into the outdoor unit, change the TXV, install a new drier, vacuum the system, open service valves. Start the system and check the charge. Still sounds like a leak. Pressures way low for R-410a.

Running under the assumption that the TXV has failed and is stuck shut, it will be very difficult to pump the refrigerant back into the compressor.

Besides, the tech didn’t know how much was in there to start with, then he added a bunch, he is not sure if there was a leak or not, there is a big question mark as to whether or not the unit is properly charged, removing it and re-charging it is the only sure way to know that the unit has the correct charge when you leave, a little more work for a lot more piece of mind.

That’s just my opinion though, some times i go a little overboard

[Kevin O'Neill]

Back when I lived in PA, we always knew the length of lines. Weigh-in was best. Now the lines run through the walls, often strange routing from outdoor unit to air handler in the attic. Often we have to add a pound over what the charts say. It all depends on local conditions. The TXV is flowing some, but yes, it may be difficult to pump down. I wonder if the tech wrote the pressures down right.

[curtbsa]

I really appreciate all the replies. A new tech came out. Said first tech had added refrigerant to do diagnostics. He replaced HVX, emptied system and refilled. Said should be good to go. Did not give me new pressure readings though. Seems to be cooling now. I'll be back if any more problems. Thanks again.

[curtbsa]

sorry, meant replaced TXV. Dealing with too many anacronyms today.

[Shophound]

For those of us techs who have had a TXV fail on us, but our initial reaction was to think the system was low on charge, I will maintain that your initial tech was correct on the TXV failure (as evidenced by the new tech replacing it and you have cooling again). The thing I have to remind myself as a tech is that my first response when I find a system with what appears to be a low charge, don't add any refrigerant until any other factor that can contribute to the same symptoms has been found and eliminated. Just the other day I had a rooftop unit that indeed was low on charge. I started to add gas but stopped myself. Partly because my eyes zoomed right in on where the leak was. I could see it even without breaking out leak detector. Partly because even if the leak had not been that obvious, it was foolish for me to keep adding gas to a system with no other factors causing it to indicate a low charge but a low charge itself, which can only be due to a leak.

Old habits are hard to break. Knee jerk reactions in service aren't always the best.

[hvacvegas]

Glad to hear they've got it working.

I agree with shophound. Sounds like he figured on bad txv, which it was. I've had txv's bad out of the box, and I've had txv's go bad after a week.

Kevin, I'm not arguing, but:
IF you thought there was the possibility of a loss of charge, why would you pump a unit back into itself? Your not worried about sucking moisture in, especially with a possible malfunctioning txv?

[catmanacman]

if a system is properly charged on start up and then the txv fails you have high sub cool and high superheat if he added refrigerant to get the proper sub cool then either the unit was not charged correctly on start up or the refrigerant leaked out.if the tech that replaced the txv followed proper procedures then the system should leak free

[chuckcrj]

Glad to hear they've got it working.

I agree with shophound. Sounds like he figured on bad txv, which it was. I've had txv's bad out of the box, and I've had txv's go bad after a week.

Kevin, I'm not arguing, but:
IF you thought there was the possibility of a loss of charge, why would you pump a unit back into itself? Your not worried about sucking moisture in, especially with a possible malfunctioning txv?

If you don't let it pump down into a vacuum you can't suck any moisture into it. I usually just get it down to 5 psi and shut it off.:.02:

[cuchulain]

In all reality your not suppose to pump a scroll compressor into a vacum state anyway

[dandyme]

A new tech came out. Said first tech had added refrigerant to do diagnostics. He replaced TXV, emptied system and refilled. Said should be good to go. Did not give me new pressure readings though.that doesn't say much for the "tech" Seems to be cooling now. I'll be back if any more problems. Thanks again.

you should ask his boss for those numbers

saying it is charged correctly and not documenting it is the same as a lie in my book

[LKJoel]

In all reality your not suppose to pump a scroll compressor into a vacum state anyway

they say not below 25psi, not enough oil pressure to maintain that thin film between the scrolls, and they start scraping against each other

[hvacvegas]

In all reality your not suppose to pump a scroll compressor into a vacum state anyway

We aren't talking about pumping a scroll into a vacuum. Not in that way.

Chuck, I know what your saying, but my only concern is with the customer. You can't tell me that needle hasn't dropped like a rock on you before. It's done it to me. On something as much of a crapfest of a happy customer as a warranty replacement coil (which btw, we are starting are rounds again....*sigh*), why take the chance? We usually just close it off, recover, repair, pump, recharge (virgin).

[JakRabbit]

TXV, he added refrigerant thinking it was low most likely but the pressures never changed. Since they didn't TXV. just let them change it a TXV is a simple device that can go bad easily.

[hvacrmedic]

if a system is properly charged on start up and then the txv fails you have high sub cool and high superheat if he added refrigerant to get the proper sub cool then either the unit was not charged correctly on start up or the refrigerant leaked out.if the tech that replaced the txv followed proper procedures then the system should leak free

A restriction at or within the metering device will cause a drop in SC.

[Shophound]

A restriction at or within the metering device will cause a drop in SC.

Thank you! I was gonna say the same but you beat me to it.

Hey folks, if you ever hear anyone dissing "all that refrigeration theory crap", tell them to take a long walk off a short pier.

[hvacrmedic]

Thank you! I was gonna say the same but you beat me to it.

Hey folks, if you ever hear anyone dissing "all that refrigeration theory crap", tell them to take a long walk off a short pier.

The problem is that some of the theory presented is wrong. We hear things like "SH and SC tell you where the refrigerant is in the system.". Well that's a nice thought. It is however a misguided thought. With a complete restriction at the MD all of the refrigerant gets trapped in the condenser and LL. Nevertheless the SC will stabilize at exactly 0.

[Shophound]

The problem is that some of the theory presented is wrong. We hear things like "SH and SC tell you where the refrigerant is in the system.". Well that's a nice thought. It is however a misguided thought. With a complete restriction at the MD all of the refrigerant gets trapped in the condenser and LL. Nevertheless the SC will stabilize at exactly 0.

Yes, my statement was based on the assumption that correct refrigeration theory was being taught. Regardless the point you raise is a good one. I would rather say "Superheat and subcooling tell you what is going on in the evaporator and condenser" vs. "SH and SC tell you where the refrigerant is in the system". The refrigerant is everywhere in the system! It's undergoing changes throughout the entire system! It's up to the tech to know what these changes signify, and whether such changes are normal or not.

With a restricted metering device, there is little heat load picked up in the evaporator entering the condenser to be rejected. Head pressure falls due to lack of heat load. Pressure and temperature are relative; if the temperature via heat load is reduced, so will the pressure be reduced. And with that the saturated condensing temp approach to outdoor ambient temp (the basis for subcooling). Liquid stacks in the condenser, reducing the amount of coil that can actually condense superheated vapor from the compressor back to a liquid. If the vapor is able to condense at temperatures near outdoor ambient temp, there won't be much subcooling.

[aircooled53]

I really appreciate all the replies. A new tech came out. Said first tech had added refrigerant to do diagnostics. He replaced HVX, emptied system and refilled. Said should be good to go. Did not give me new pressure readings though. Seems to be cooling now. I'll be back if any more problems. Thanks again.

I would ask what the pressure where /temps and T.D. after charge. You are owner of system..Required info..:.02:

[jpsmith1cm]

Skilowyo,


Please start a new thread if you need help.

[openclasspro]

What was the ambient temperature? He didn't calculate superheat, which would have been really nice to know. Shooting from the hip, yes you have a leak and a 7* split (with missing information) could be a TXV, but I'd need more info to be exact.

He should have noted superheat,on a fixed txv,mfgs wants 10-11 degrees subcooling,the superheat is what it is at that designed subcooling number.