AC only works well above 40mph
 

Hi all. I have a 380 SEL, and I recharged the AC last August/September, I think, and had the system checked. It worked ok then, but the temps were getting lower then.


Now, if I dont keep moving and the temp is over 80* (currently temps are around 80-88), it doesnt cool very much. The air is cooler than the outside, but not bone chilling like it is supposed to be in comparison on max cold. On the highway, it got kinda chilly, but the temp was falling down into the upper 70's and I was doing around 50-60mph, and had consistent RPM's of 1500-2300 (hilly terrain).


Have I given enough information for a ballpark guess as to my problem? Any ideas?

Thanks,

Does not sound like you are moving enough air through the condenser. Check out your electric fan in front of it to insure it is coming on when it is supposed to.

Also, you need to check the charge, it could be a little low on refrigerant.

Have a great day,

I'd agree that this is a classic low charge due to a leak (a modification of the old story of "charge in the fall, springtime won't cool at all").

Leak test while there's some refrigerant still there, fix leak, recharge. A6 series compressors are often checked by the pros for shaft seal leaks. FWIW

The most typical reason is that your Freon charge is low again. You have a leak. Most likely place where a leak will develop is the valves where the system charging equipment attaches.

If the EPA were really concerned about Freon loss they would mandate a better valve design. Something with a more positive shutoff and something that would not deteriorate with age.

Ken300D

Actually NO is the answer to your question. It is only remotely possible that there is enough info to assume a refrigeration problem, let alone pin that problem down to state of charge.

I kind of find it interesting that we are now discussing leak problems. If we decide from your info that the refrigeration is the problem, are we using a statistical analysis to assume state of charge is the refrigeration problem?

Other posibilities include control problems, airhandling problems, and/or heater problems. The three poor running AC systems I diagnosed this week were: plugged expansion valve - a refrigeration problem, a defective recirculate door - not a refrigeration problem, and a too large of a gap for the clutch that would quit applying after getting hot - not a refrigeration problem directly.

Mind you, I wouldn't have been diagnosing them if they had been low on refrigerant.

Certainly a lot of things can go wrong to impact the A/C system. Considering a Freon recharge was recently required - and no mention of leak repair - the most likely trouble area to check first is the state of freon charge. Fairly easy to check too.

Now, if I were making money on the process, then I'd lay out a long list of things to check and go over them painstakingly one at a time.......

:)

Ken300D

"Now, if I were making money on the process, then I'd lay out a long list of things to check and go over them painstakingly one at a time......."


Ah, but if you wish to make money doing it as a profession you are better off quickly finding the one problem and fixing it. This isn't the government you are working for.