AC not working. Replace TXV or whole coil or whole AC unit?
#1
06-25-17, 04:45 PM
AC not working. Replace TXV or whole coil or whole AC unit?
My 5 year old 4-ton Carrier A/C unit (Air handler CNPVP4821 with TXV, Outdoor unit CA16NA048 has stopped cooling. If I turn off the system for 3 hours, it would cool for the next hour than ice up. Two Techs have seen it.
The first one said that – a) system is low on Puron and b) the TXV needs to be replaced. He did not use a leak tester and all his testing was with the coils still iced up. When he tested the outdoor unit, he had to call his back office to report an error code “OL” on his tester. He quoted $2200 for TXV replacement, but said that there is no guarantee it will fix the problem. He said that I may have to replace the coil as well for an additional $3500.
The second one came to the same conclusion – system low on Puron and TXV needed replacement. He waited for the ice to melt and used a leak tester on the coils, the TXV, and also the outdoor unit, but it did not detect any leaks. He thinks the TXV is clogged up, but had no explanation for the low level of Puron. He will quote a price for TXV replacement tomorrow after he gets the part cost from Carrier.
What should I do - get the TXV replaced, or the whole cased coil unit replaced or the whole AC system replaced?
The first one said that – a) system is low on Puron and b) the TXV needs to be replaced. He did not use a leak tester and all his testing was with the coils still iced up. When he tested the outdoor unit, he had to call his back office to report an error code “OL” on his tester. He quoted $2200 for TXV replacement, but said that there is no guarantee it will fix the problem. He said that I may have to replace the coil as well for an additional $3500.
The second one came to the same conclusion – system low on Puron and TXV needed replacement. He waited for the ice to melt and used a leak tester on the coils, the TXV, and also the outdoor unit, but it did not detect any leaks. He thinks the TXV is clogged up, but had no explanation for the low level of Puron. He will quote a price for TXV replacement tomorrow after he gets the part cost from Carrier.
What should I do - get the TXV replaced, or the whole cased coil unit replaced or the whole AC system replaced?
#2
06-25-17, 10:16 PM
Forum Topic Moderator
If the coil model number ends with ALA---- then get the TXV since you have an aluminum coil.. ( the dashes might be AAAA or ABAA)
If it ends with something else then I would look at the level of rust on the coil.
When a TXV fails it often looks like the system is low and the tech adds refrigerant but it will not help.
I would see if that coil or TXV is at least under a parts warranty.
If it ends with something else then I would look at the level of rust on the coil.
When a TXV fails it often looks like the system is low and the tech adds refrigerant but it will not help.
I would see if that coil or TXV is at least under a parts warranty.
#3
06-26-17, 06:15 AM
The 2nd tech did add refrigerant before he used the leak tester. Still his tester did not generate any leak beeps on the coil and TXV. The Carrier website shows the model number CNPVP4821ATAACAA as a cased coil. The tubing is all copper. His leak tester did generate an occasional detection near the compressor - like 1 in 10 times - but it was not repeatable.
Thanks a lot for your help.
Thanks a lot for your help.
#4
06-26-17, 07:15 AM
Forum Topic Moderator
That T indicates tin coat tubesheet. I would expect to see a rusty tubesheet in my humid climate but your area is probably much drier.
If the txv is bad almost every tech is going to wanna add refrigerant. This doesn't necessarily mean it needed refrigerant. If it is restricted the low side pressure will be too low or possibly even a vacuum.
You got some high quotes.
If the txv is bad almost every tech is going to wanna add refrigerant. This doesn't necessarily mean it needed refrigerant. If it is restricted the low side pressure will be too low or possibly even a vacuum.
You got some high quotes.
#5
06-26-17, 08:18 AM
There is rust around areas where the tube elbows enter the flat sheets. The second tech quoted $500 for TXV replacement including parts and labor. He will include the refrigerant because he thinks only a little additional refrigerant will be needed. I am assuming that the existing refrigerant has not become contaminated. He said he is quoting a low amount because I took care of him when he became ill on site due to heat exposure.
The new cased coils on the Carrier website show Aluminum tubes. If I replace the entire cased unit, I will get Aluminum tubes. Should I replace just the TXV or the entire cased coil unit. Thanks.
Vertical Cased Evaporator N Coil - CNPVP | Carrier - Home Comfort. My coil tubes look like this Vertical Uncased Evaporator N Coil - CNPVU | Carrier - Home Comfort.
The new cased coils on the Carrier website show Aluminum tubes. If I replace the entire cased unit, I will get Aluminum tubes. Should I replace just the TXV or the entire cased coil unit. Thanks.
Vertical Cased Evaporator N Coil - CNPVP | Carrier - Home Comfort. My coil tubes look like this Vertical Uncased Evaporator N Coil - CNPVU | Carrier - Home Comfort.
#6
06-26-17, 11:45 AM
Do you still have the same problem after the second Tech added refrigerant into the system ? IF you still have the iced coil, then replace TXV only. The coil should last much longer then 5 years.
#7
06-26-17, 02:24 PM
Yes, I still have the same problem. The coil shows signs of significant rust. I am trying to decide whether to bite the bullet and spend the additional $900 to replace the entire cased coil which comes with a factory installed TXV as well. Thanks a lot for your help!
#8
06-26-17, 09:27 PM
Not sure why you got so much rust on a 5 year old coil. Usually we don't replace coil unless it is leaking, but it is up to you. (Already 5 years ? your coil should have 5 year warranty)
#9
06-27-17, 05:24 PM
I had another tech take a look. He had no doubt the problem was the TXV. He took just a few minutes. He used his gauges at the service ports on the outdoor unit. The high side and low side readings were 450 psi and 60 psi. He said that 60 was too low, and that if there was a leak, both sides would have been low. The sub-cooling temp was 25 degrees. He said it was clear that the TXV was restricted. He did not even open the air handler unit.
Does that all sound reasonable? I will go forward with TXV replacement. Should I insist on new refrigerant charge or is it okay to reuse what is in the system today? Thanks.
Does that all sound reasonable? I will go forward with TXV replacement. Should I insist on new refrigerant charge or is it okay to reuse what is in the system today? Thanks.
Last edited by rjmpls; 06-27-17 at 05:39 PM. Reason: Added the last question.
#10
06-27-17, 05:45 PM
Member
it does sound reasonable.
but a restriction elsewhere could cause the same issue.
should be okay if the repair is warrantied; should give you readings after the fact.
but a restriction elsewhere could cause the same issue.
should be okay if the repair is warrantied; should give you readings after the fact.
#11
06-27-17, 06:25 PM
Group Moderator
We're riding a thin line here. The DIY administration does not allow us to discuss charging methods and pressures.
You have a tech changing the valve. He'll know which refrigerant is best to use.
You have a tech changing the valve. He'll know which refrigerant is best to use.
#12
06-28-17, 07:16 PM
Member
He's not asking how to break the law and charge his own unit or even which refrigerant to use.
just reporting the tech's findings and asking whether a licensed person should be recovering and replacing the refrigerant or pumping the system down.
answering those questions won't provide enough info for someone to break the law and handle refrigerants without a license, and that's the whole point of the rules, no?
just reporting the tech's findings and asking whether a licensed person should be recovering and replacing the refrigerant or pumping the system down.
answering those questions won't provide enough info for someone to break the law and handle refrigerants without a license, and that's the whole point of the rules, no?
#13
06-28-17, 07:18 PM
Group Moderator
