Does R134a deteriorate?

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I just checked the pressure on the low and high side of my AC in my SC300, pressure is good (225 high side) but it seems like my air discharge temps have dropped over the last few years. It used to be super icey cold even on very hot days, now it's not nearly as cool. It got me thinking, I've never recharged this AC. As far as I know, it has not been recharged in nearly 150K miles (compressor was replaced at 50K miles on warranty) Does R134a go bad over the years, is it likely the compressor failing, or some other explanation?
 
I would be concerned about it not being as cold. The seals on ac compressors on cars slowly leak over time. Home refrigerators and such are hermetically sealed. Hence the reason they stay efficient for many years.
 
No Refrigerant does not deteriate. Many things can effect vent temp such as a low or over filled system, Weak compressor, Bugs plugging up the condensor fins, foam letting heat get around a blend door, leaking heater valve etc.
 
Originally Posted By: Chris142
No Refrigerant does not deteriate. Many things can effect vent temp such as a low or over filled system, Weak compressor, Bugs plugging up the condensor fins, foam letting heat get around a blend door, leaking heater valve etc.


+1

A properly functioning a/c will not deteriorate in performance. Plugged condensers, bent rods, etc... can cause problems. As long as your system isn't over charged and not full of oil, everything should be fine inside.
 
Probably the seals shrinking a little bit over time, allowing some refrigerant to escape. It might be time to have it evacuated, evaluated for leaks, and then recharged again.
 
Even if everything in the system was perfect as the day the car was built the R134A will slowly leak out of compressor seals. Just a function of the design of the seals. It may take many years though.....
 
As others have eluded to, check the air flow through the condenser, evaporator core and cabin air filter.

I saw an evaporator core literally plugged solid with gunk - so no air flow through it. The pressures checked okay, but it wouldn't cool. After lots of chemicals and air, the core was clean again and the A/C was functioning as it should.
 
Originally Posted By: Bluestream
Try checking your cabin air filter as well.


+1 and/or clean the evaporator.

Does it not do as good at idle, but seems normal when going down the road/highway? if so that is a good indication of an undercharge.
 
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