AC dryer now a maintenance item?

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Avery4

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Jan 29, 2014
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What's up with AC accumulator/receiver dryers now apparently being a maintenance item? Now we have Tesla requiring a replacement every 2-6 years depending on the model, GM requiring a replacement every 7 years on at least one model (the Traverse), Delphi recommending a replacement every 2 years, and Valeo recommending a replacement every 3 years. What is this about? I never even heard of replacing AC dryers preventatively until a friend with a Tesla told me that he had to have his replaced and I thought the dealer scammed him until I did some research and saw that's actually a thing now.

I can only think of two possible theories for why this might be. Either the new R1234YF refrigerant or its oil is degrading the desiccant or there has been a major change in the way they are being made, although neither theory makes much sense. Does anyone have any other ideas on why AC dryers apparently have to be replaced as part of scheduled maintenance now?



https://cdn.dealereprocess.org/cdn/servicemanuals/chevrolet/2019-traverse.pdf (page 371)

www.delphiautoparts.com

Why and When to Replace Receiver Driers

Receiver driers are there to absorb corrosion-causing moisture and to filter any particulates that are circulating around the system,..
www.delphiautoparts.com

www.valeoservice.com

Receiver Drier for Car Air Conditioning System

The receiver drier is a component that protects all the other parts of the A/C loop. It is located between the condenser outlet and the expansion valve inlet, on the high-pressure side of the car A/C loop. The receiver drier has different roles:
www.valeoservice.com www.valeoservice.com
 
Weren't they always considered a "maintenance item"?

IIRC, one shop manger refered to it doing a job similiar to what an oil filter does for an engine.
 
Oillover said:
Weren't they always considered a "maintenance item"?

IIRC, one shop manger refered to it doing a job similiar to what an oil filter does for an engine.
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Not sure, but this is the first time I'm hearing of it. I've only replaced them when the system had to be opened and never even considered replacing them preventatively.

Yes, one of the dryer's functions is to filter any small particles out of the refrigerant and oil, but since the AC system is normally sealed and self contained unlike an engine, there shouldn't be much to filter out. If the compressor was wearing to the extent of clogging the dryer with metal shavings, it would seem to me that the dryer being clogged would only be a symptom of the actual problem.
 
nwjones18 said:
We've got a 1993 Crown vic with its original R-12 that says its not necessary very often.. haha. I don't see how it could ever be required assuming the system isn't open unless the new freon/oil is affecting it somehow.
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Good to know. I have a 1997 Civic with 354K southern miles on its original R134a AC system and it still works perfectly, so it seems like its dryer has held up alright too.
 
From the 2023 Chev Silverado owners manual:

6CE6130C-2D83-477A-AE54-A02E3552D893.jpg
 
Sounds like a scam to me. Unless the system has been open or is leaking there should be no reason to change the dryer. The only point of the desiccant is to catch any moisture in the system. Moisture is not going to get in if its not been opened up or messed with.
 
CDX825 said:
Sounds like a scam to me. Unless the system has been open or is leaking there should be no reason to change the dryer. The only point of the desiccant is to catch any moisture in the system. Moisture is not going to get in if its not been opened up or messed with.
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I agree that moisture shouldn't get in unless the system has a leak or was opened in some way, but if a car manufacturer wanted to require unnecessary services just as a scam to increase profits, I don't see why they would pick something so strange and illogical while going out of their way to promote "lifetime" fluids, "lifetime" timing chains, ridiculously long oil change intervals, etc.

It seems especially odd for Tesla since one of their major selling points is their vehicles being nearly maintenance free and they have apparently revised their maintenance schedule several times to reduce maintenance such as by testing the brake fluid instead of flushing it, no longer requiring battery coolant changes, etc. You'd think they could have created an AC dryer capable of lasting a bit longer than 2-6 years if they wanted to.
 
Only if the system has been empty for a while. Say you drive with it not working for a few months before you couldnt afford to fix it, I'd change it. Supposedly if exposed to the atmosphere it absorbs too much moisture and isn't good anymore.
 
A perfect maintenance regimen for an automotive A/C system after X amount of years would be to evacuate the refrigerant out of it and pull a vacuum on the system. Measure the amount of refrigerant that came out compared to what's supposed to be in the system (the a/c machine will do this), leak check. Again, the machine will do this. Replace the service valves, dryer, orifice tube(s) and recharge with the spec'd amount of refrigerant and oil.

With exception of changing the service valves and orifice tube, all of these things would have to be done to change the dryer desiccant.

With R1234YF refrigerant, this would be a very expensive service.

Watch some R1234YF videos. The machine takes hours to perform this service.
 
Hyundai uses a lame plastic cap with an allen hex on it for a plug. Good luck getting one of them out after 100k miles in one piece. When you buy a kit online it includes everything but the cap. :(
 
JTK said:
A perfect maintenance regimen for an automotive A/C system after X amount of years would be to evacuate the refrigerant out of it and pull a vacuum on the system. Measure the amount of refrigerant that came out compared to what's supposed to be in the system (the a/c machine will do this), leak check. Again, the machine will do this. Replace the service valves, dryer, orifice tube(s) and recharge with the spec'd amount of refrigerant and oil.

With exception of changing the service valves and orifice tube, all of these things would have to be done to change the dryer desiccant.

With R1234YF refrigerant, this would be a very expensive service.

Watch some R1234YF videos. The machine takes hours to perform this service.
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That's debatable IMO because any time the system is serviced is a potential opportunity for contamination, undercharging, overcharging, over oiling, under oiling, defective parts, broken nuts/bolts, etc for questionable at best improvements.

But if we are going to go with that procedure, may as well replace the condenser while the system is open if there is any significant fin damage as there usually is on vehicles with a lot of highway miles.

Is there any evidence on whether or not the compressor oil significantly degrades over time? I'd think it would since it's exposed to the high temperatures inside the compressor, but then again, there shouldn't be many contaminants for it to react with either.
 
Avery4 said:
That's debatable IMO because any time the system is serviced is a potential opportunity for contamination, undercharging, overcharging, over oiling, under oiling, defective parts, broken nuts/bolts, etc for questionable at best improvements.

But if we are going to go with that procedure, may as well replace the condenser while the system is open if there is any significant fin damage as there usually is on vehicles with a lot of highway miles.

Is there any evidence on whether or not the compressor oil significantly degrades over time? I'd think it would since it's exposed to the high temperatures inside the compressor, but then again, there shouldn't be many contaminants for it to react with either.
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That's the only thing that hasn't been replaced on my truck. The only bent fins are at the top because it sticks out and people bend them when they lean over to work on it.
 
Avery4 said:
...Is there any evidence on whether or not the compressor oil significantly degrades over time? I'd think it would since it's exposed to the high temperatures inside the compressor, but then again, there shouldn't be many contaminants for it to react with either.
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Assuming the system hadn't been touched since the factory, I would think the whole purpose of doing this service is to determine if you have the specified amount of refrigerant in the system and there are no leaks. The refrigerant and oil won't break down unless the system breaks down.

I'm definitely not saying to do this service. I'm just suggesting a perfect world scenario. My luck, I'd do this and then get a hole in my condenser the nest week.
 
Just a guess, but electric vehicles have air conditioning compressors that are ran by an electric motor. And the electric motor has wires with varnish. If over time some of that varnish were to get into the oil and refrigerant then it could find its way to the desiccant in the dryer. After a while it could clog the dryer up enough that the air conditioning system would stop working. That would actually probably cause an overpressurization. But systems probably have a sensor that would shut off the compressor in that case. If they do, then if it were mine I would just run it until it decides to stop working. All this is speculation, but I do know that electric vehicles do have electric motors driving the compressor for the AC. Also, these motors run on very high voltage. Because of that, it is very important that the servicing equipment be dedicated to servicing that type of a system because the oil has to be extremely clean of moisture, much more so than a normal air conditioning system on a vehicle with a belt driven compressor. Also the oil is a whole another grade better as far as how much moisture is not in it before it is installed.
 
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