Automotive Air Conditioning Information Forum

Hello. I have a 2011 Hyundai Tucson. The a/c has gradually deteriorated over time to the point where it no longer produces cold air. I suspected a low charge and bought an Avalanche recharge kit from the local auto parts store. When I connect to the low side with everything running I get a pressure of ~95 psi. I live in Florida and the temp was 90+F. I suspect this corresponds to the vapor pressure of the refrigerant at that temp. The compressor clutch appears to engaging (I hear it engaging and see the compressor spinning) but there is not the usual change in engine load that I experienced before the system crashed. I did not try to add any refrigerant to the system per the instruction on the recharge kit. I do not hear any abnormal noises from the compressor. Could this just be a case of low refrigerant or something more sinister?

So, you bought the Avalanche recharge bottle but did not use it, correct?
GOOD, because I googled it and it has sealer in it.
NEVER USE SEALER NEVER USE SEALER NEVER USE SEALER did I mention NEVER USE SEALER You will ruin your system and be looking at a huge repair bill.

Most likely the system is just low on charge. There may also be a leak, but any system can loose a small amount a year normally.
Over 65% of the reasons for lackluster AC performance is merely low charge.

Have a shop reclaim what charge is in there, and then let them vacuum down and fill it with the correct charge by weight, which is on a sticker under the hood.
Then start looking for leaks or better yet let the shop do it.

Best to go to a dedicated AC repair shop, and leave Bubba's tire, battery, tattoos, pizza, and AC repair shop to some other sucker.
It should not be overly expensive to suck it down and recharge, then you go from there.
Look for the MACS emblem

Be certain the plastic caps are on the access ports, they actually complete the seal at the access ports

In the meantime, do not run the system at all, because no oil will be getting back to the compressor and you will turn the compressor into a boat anchor

mrfezziwig wrote: ↑Wed Sep 22, 2021 1:59 pm When I connect to the low side with everything running I get a pressure of ~95 psi. I live in Florida and the temp was 90+F. I suspect this corresponds to the vapor pressure of the refrigerant at that temp. The compressor clutch appears to engaging (I hear it engaging and see the compressor spinning) but there is not the usual change in engine load that I experienced before the system crashed.

That reading sounds more like the static pressure. Double-check to ensure that the compressor is actually turning over and not just the outer clutch pulley, especially since you didn't notice any change in engine load.

mrfezziwig wrote: ↑Wed Sep 22, 2021 1:59 pm Could this just be a case of low refrigerant or something more sinister?

It sounds to me like a low refrigerant charge as well, probably due to small seasonal losses on a ten-year-old vehicle, or a leak, as mentioned earlier.

tbirdtbird wrote: ↑Wed Sep 22, 2021 3:59 pm Have a shop reclaim what charge is in there, and then let them vacuum down and fill it with the correct charge by weight, which is on a sticker under the hood. Then start looking for leaks or better yet let the shop do it.

I would begin with that procedure, too. If the under-hood decal is missing, my data sources specify 18 ounces net weight of R-134a and 3.7 to 4.4 fluid ounces of PAG-46 oil.

OK. I took the car to the shop today. The refrigerant was very low and so they recharged the system. Unfortunately, this did not fix the problem. After more analysis the conclusion was that the compressor is bad. The technicians working on the car stated that the system did not reach the required working pressures. They backed this up by saying they could feel the 'sucking effect' on the compressor input side but could not feel a corresponding 'pumping action' on the output side. I believe this observation was made by grasping the metal piping leading to and from the compressor. There were no unusual noises from the system and there was no obvious leakage (dye was included in the recharge). As you can imagine, replacing the compressor and associated components is not cheap. My questions are:

1). Does the diagnosis sound reasonable? Is there more that should/could be done to verify that the compressor is indeed the problem?
I don't want to spend money without exhausting all other possibilities.

2). The recommendation was to replace the compressor, expansion valve and the receiver drier. This also included a system flush.
The owner stated that replacing the compressor only would invalidate the warranty because there may be 'bad' things left
in the system from the compressor malfunction and a flush would not guarantee their removal. He said if, after removing the
compressor, there was no sign of metallic residue he would give me the option to stop there on the understanding that
this might invalidate the warranty. What are your thoughts?

Thanks.

Take it to a shop that has a better understanding of auto a/c systems.

MACS Find a Shop.

Is this a dedicated AC shop, or a pizza shop with an AC guy working in the back out of a station wagon. Can you get a recommendation from friends as to a good shop in the area?
It seems that you do not do any of your own work, such as renting gauges at Autozone.
Without having an AC manifold connected up so that hi and low pressures can be determined, that it may be tricky to determine if the comp has failed, at least that is how it seems to me

Replacing the drier is a given if the system is opened. Changing the TXV can never hurt.
I am a bit concerned, tho, because if the compressor is changed out due to failure, the condenser MUST also be changed out, and they didn't seem to mention that. And please know that condensers cannot be flushed.
They will know if the comp failed because when the system is opened, the oil will be discolored, maybe even black, and would probably contain bits of aluminum

Perhaps JohnHere, who also commented on your issue, will return and comment

Oops, Tim beat me to it. He knows what he is talking about.

I would lean on the information provided, which may not be accurate due to improper diagnosis.

Leak and maybe control valve.

CV 43-3458

All good comments. This appears to be a good locally owned family business with all the right gear. I was allowed in the shop and they showed me exactly what they were doing. Certainly not a 'Pizza Joint' type place. I have not used rented gauges but I could probably ask the shop to give me readouts from their machine if that helps. I mentioned to the owner that I was thinking about recharge with Avalanche kit and his eyes almost popped out of his head ... basically saying what others have said. I am a retired professional engineer with a pretty decent understanding of thermodynamics, so I think I can ask the right questions. The question is "have I done due diligence?"

Your Hyundai uses a variable displacement compressor, it will be at it's minimum angle if turning it over by hand, just barely pumping. The best scenario is these guys who looked at your car might be out of their depth, worst case they are trying to make their boat payment with unnecessary repairs. I would bet you only need a proper recharge, and besides the first step to troubleshoot should be to recover the existing refrigerant, pull a proper vacuum and recharge to the underhood sticker weight. Can you take it to another shop? and just ask for a recharge?

Hyundai dealer told me that the 2011 takes this part # https://www.hyundaioemparts.com/oem-par ... MlM1MDA%3D or after market https://www.napaonline.com/en/p/ACKTEM57520NK. This appears to have a clutch. I thought Variable Displacement Compressors were 'clutchless' but I'm not 100% sure. The tech at Hyundai didn't seem to know either.