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Subcool high

Posted by donaldj (My Page) on
Sun, May 11, 14 at 7:26

My 12 year old Carrier Puron upstairs system was not cooling. Tech man indicated puron was gone due leak in a-coil. Tech said I had a choice of replacing inside and outside units, or just replacing the inside coil 1st. I told him to replace coil first and see how it worked. They replaced the 3ton a-coil saturday morning with a Carrier
CNPVP3617ALA and seemed to work fine for one day. Then blowing hot air again. Called the tech again and he did not want to come out and check it. He insisted on replacing the condenser.

I decided to get a 2nd opinion before replacing condenser. I had the tech that originally installed the system 12 years ago check it out. The psi temp started at 95, and went up to 100. Temperature was only about 80. The line temperature was 75 which he said gave a subcool 25 difference. He said difference should be 15, and it appeared to be overcharged. Suggested I have the other tech adjust it which he should not charge for. Called the 1st tech back again and told him the 2nd tech's opinion. 1st tech had a raging cussing fit and said he didn't like me accusing him of making a mistake. He said he filled it with 6.75 pounds plus some extra for the extra line length going upstairs (35 feet total). The info on the unit was faded, but I was able to read that the
recommended charge was 6.25 pounds. Could an extra 0.5 pounds charge cause the problem? Will it damage my compressor to run with a little overcharge?

So it looks like the 1st tech is refusing to do any analysis work on the unit. Can someone explain my warranty
situation? If I call the 2nd tech or a 3rd tech to adjust the charge, should that repair be considered under warranty?
I will be contacting Carrier 800 number tomorrow to complain about the 1st tech service and get their suggestions.

This post was edited by donaldj on Sun, May 11, 14 at 8:15

Follow-Up Postings:

RE: Subcool high

So I have to discount everything the tech said that did the "service" work on it. Under no circumstances should you ever tolerate anyone going into a rage or cussing at you. He needs to be unemployed until he understands that's never okay. I've seen too many guys who guess about the problem. The biggest problem with AC units is the lack of qualified installers and service people.

It sounds like the person who installed it is the guy you want working on it... Someone who actually measures and tests things.

RE: Subcool high

I am curious as to why you didn't have the original installer (2nd tech) do the initial repair.

I don't think complaining to Carrier about the 1st tech technical and customer skills will get you any satisfaction. You need to speak with the owner of the business.

RE: Subcool high

>why you didn't have the original installer?
I don't see why it matters who installed it 12 years ago.
It is long out of original warranty. Do you go to a new car dealer for all your repairs when your car goes out of warranty? I don't. I go to internet sites and check ratings and choose someone with a good rating. The 1st new tech had a good rating somehow, but didn't work out for me. Would appreciate it if responders would address my questions. I made similar post on another board and was unable to get all my questions answered there.

This post was edited by donaldj on Sun, May 11, 14 at 11:54

RE: Subcool high

"Would appreciate it if responders would address my questions. I made similar post on another board and was unable to get all my questions answered there."

Hmm, seems like a pattern.

Any ideas why?

This post was edited by saltidawg on Sun, May 11, 14 at 12:24

RE: Subcool high

>Any ideas why?
The other board was for contractors and refused to answer any questions they might consider DIY. I don't see any pattern here except 2 guys with DOG in their userid.

RE: Subcool high

"Do you go to a new car dealer for all your repairs when your car goes out of warranty?"

Actually for repairs I can't do I go to the dealer. I have tried other places for brake repairs and I have not been impressed. The Honda dealer I use charges less for timing belt replacements and brakes.

"Tech man indicated puron was gone due leak in a-coil."

If the leak was in the coil then why does he want to change the condenser?

"Could an extra 0.5 pounds charge cause the problem? Will it damage my compressor to run with a little overcharge?"

Overcharging by 0.5 pounds will likely not cause damage. If it were overcharge I would expect the coil to freeze up.

"Can someone explain my warranty situation?"

None of us were present when the warranty terms were discussed. Do you have anything in writing?

"If I call the 2nd tech or a 3rd tech to adjust the charge, should that repair be considered under warranty?"

If a warranty for the original work exists, then it will have to be done by the original HVAC company.

Did I answer all your questions?

RE: Subcool high

I don't think it is over charged. If it worked for one day, that means system was fine, not over charge. plus 0.5 lb won't make much difference anyway.. I am thinking may be there is a leak, therefore, after a day, your freon level is too low. This is an installation issue. I bet he did not check the system for leaks after the install.

RE: Subcool high

>If the leak was in the coil then why does he want to change the condenser?
As I said above, the CNPVP3617ALA was first replaced. It worked fine for one day, then the compressor started going off. From what I've read 410a systems are very sensitive to having the correct charge level.

>Do you have anything in writing? I have the Carrier 10/1 parts/labor warranty document on the CNPVP3617ALA. That is the entire interior piece that fits above the furnace and contains the coil and TXV and whatever else.

RE: Subcool high


I didn't address the actual problem because there's just too much information that's missing and untrustworthy (not saying you are untrustworthy...saying I don't trust anything that was done up to this point).

What warranty situation are you wanting explained? I would guess that the coil is warranted by Carrier to be free from defects. To the extent there's warranty on the work that was done, that's going to be honored by the company that you hired.

Look, you have a couple options:

1. you can call the company back that did the bad work and get a different tech.. if that's not an option (is a one man shop or you were working with the owner) then you need write that off. BTW: It wasn't that "it didn't work out".... nobody gets to go into a rage and cuss at the customer... and that doesn't begin to address his technical skills.

2. you can call someone else in and they will charge you to fix the problem.

I'm not going to guess if it's undercharged, overcharged, has a faulty TXV , wasn't properly evacuated, etc. because it could be any of those things or a combination.

You really do need to have someone who knows what they are doing work on it. That needs to be someone who's willing to measure and test and not guess.

If this were my job I would be very tempted to recover the charge, evacuate it correctly (which would also let me know if it was leaking) then charge it properly.
That's about the only way I would have any confidence in the system.

This post was edited by jakethewonderdog on Mon, May 12, 14 at 8:11

RE: Subcool high

The compressor comes on about 1/2 the time I start it up. Today temperature/humidity was 77/76. The liquid line temp was (76,76) (1st number is 3ton upstairs which was failing, 2nd number is 2ton downstairs which is working ok). Cool line temp was (57,50). Hot air blowing out of condenser was (91,92). Cool air blowing out vents was (53,57). The 53 number is low because that vent is right next to the indoor blower. Would a hard start kit maybe be all it needs ?

This post was edited by donaldj on Mon, May 12, 14 at 23:45

RE: Subcool high

The hard start kit may solve it. It could also be a bad contactor causing an intermittent connection.

RE: Subcool high

Why are you guessing about a hard start kit?
Was it having a problem starting before the indoor coil was changed?

If you aren't willing to recover the charge, evacuate and re-charge at least make sure the thing is charged properly before you do anything else. To do that your tech will use the sub-cooling method (nothing else... no guessing, no winging it, no feeling the return line and guessing it's cool enough).

Since the guy who installed it seemed to understand that, I would get him out there and pay him to get that right.

Only once that's correct should you move on to do additional troubleshooting.

This assumes that the unit was properly evacuated when the coil was replaced and that the coil was properly sized.

Below is a link explaining the subcooling method of determining the correct charge for the unit. This is what your tech needs to do.

Here is a link that might be useful: how to charge unit by sub-cooling

RE: Subcool high

jake, the old system was from 2002 and probably didn't have a txv. systems with a txv and longer line do need a start assist kit. the kit should never cause a problem. One tech wanted $269 for the kit, parts only. My last repair in Dallas was $300 for a $15 capacitor install. I can do those things myself now after a little research. I am familiar with subcool and have read that 2/3 of systems are not properly charged.
Yes, I plan to have it adjusted after putting the hard start kit on so it will start up without paying a $269+labor+call bill. I also will be putting in a wifi thermostat as the old cheapy one is stuck in auto with the lever broke off. If I can't the thermostat working, I will pay the tech to do it also. After I get it running, I should be able to get an exact quote for adjusting the charge, which is probably overcharged a small amount.

This post was edited by donaldj on Tue, May 13, 14 at 18:41

RE: Subcool high


Googling the part number of the indoor coil you just installed shows it has a TXV. The second person that you had out seemed to understand how to charge your system based on the information you have given.

If you are saying the first coil used a capillary tube and the new coil uses a TXV, then I'm not sure you can use the recommended charge on the nameplate. At any rate you will have to use subcool to get it right now.

Fix the stuff you can fix yourself - fine. But I agree with the 2/3 of systems not charged properly. I would add that they often aren't evacuated properly and otherwise some really bad installations.

Also, make sure all of your airflow is good (clean filters, clean secondary heat exchanger if you have it. Your coil is new, but for others who read this, be sure your indoor coil is clean too.) You can't charge a system properly if the coils aren't clean or you don't have the airflow.

RE: Subcool high

New tech came today. He had the nice meter that showed everything on one meter. Subcool was 17, when rated for 15, so he did not remove any charge. I think the other guy who measured 25 for subcool did not let it run a full 15 minutes to level out the system. Anyway, has been running fine for 4 hours now.

RE: Subcool high

Did you install the hard start kit?

RE: Subcool high

It's a must to know the subcooling with a TXV, but the superheat should be checked as well to make sure the TXV is maintaining the superheat (Usually 8-15*)- depends on the system.
If the target is 15, 17 should be fine.
Of course the static at the indoor system must be correct before knowing these tests are within range. Bad cfm inside will make all readings useless.
A tech must calibrate his/her testing equipment once in a while too. LOL.

RE: Subcool high

superheat was 10. yes, I am using a hard start kit. Don't think it would go without it. Not sure how long it will last with it either. But 1st 24 hours have been fine.

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