AC problem, can someone shed some light?
Thread Starter
Melting Slicks
Joined: Feb 2006
Posts: 2,092
Likes: 5
From: Fayetteville Arkansas
AC problem, can someone shed some light?
never had any problems with my 2000 A4 coupe in any of the HVAC areas...until now. Three and a half hour trip and AC is working fine until it seems to be making a fluttering noise...kinda like a flag in the wind...and this is noticed after I turn it to max on the controls. Barely any air is coming out but what is coming out is very cold still. The display on the dual zone climate control shows it is at max but it is barely blowing. Got to where it was hot in the car and I shut the AC completely off and put the windows down. On the way home today about two hours into the trip it did the same thing with reduced function. What is the deal? I searched the forum for info on this and the blower motor and really found nothing. Any ideas and help would be greatly appreciated. Again in short, it works just fine for a few hours but then the function of the blower is decreased to very minimal. Next day everything fine again until a few hours of usage and then barely blowing again.
Thanks, Thomas
Thanks, Thomas
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
There may be a problem with the low pressure switch. The switch is set to shut off the compressor if the low side pressure goes below a certain point. This point usually equates to an evaporator temp of 36 to 38 degrees farenheit. If the switch allows the pressure to go too low the evaporator temp will drop below freezing and the moisture in the air will freeze and block air flow through the evaporator. Since this takes some time you would get the symptoms you are describing. You may also feel fine pieces of ice blowing out of the center vents.
Bill
Bill
Thread Starter
Melting Slicks
Joined: Feb 2006
Posts: 2,092
Likes: 5
From: Fayetteville Arkansas
that's an idea...
but any fix to that problem...???? Or any other ideas? Drove the car this AM to work and absolutely no problems with the AC on manual or Auto... and there was no problem with switching from low to high with how the AC was blowing. If it is the low pressure switch should I just leave it alone since I only only notice it on long trips or should I get it fixed now?
Thanks again, Thomas
Thanks again, Thomas
Burning Brakes
Joined: Nov 2002
Posts: 807
Likes: 21
From: Los Altos CA
Originally Posted by Bill Dearborn
There may be a problem with the low pressure switch. The switch is set to shut off the compressor if the low side pressure goes below a certain point. This point usually equates to an evaporator temp of 36 to 38 degrees farenheit. If the switch allows the pressure to go too low the evaporator temp will drop below freezing and the moisture in the air will freeze and block air flow through the evaporator. Since this takes some time you would get the symptoms you are describing. You may also feel fine pieces of ice blowing out of the center vents.
Bill
Bill
Thread Starter
Melting Slicks
Joined: Feb 2006
Posts: 2,092
Likes: 5
From: Fayetteville Arkansas
low pressure switch....
ok ... then what is the correct way of diagnosing this problem or should I just replace the switch ?
Thanks so much for any help in advance,
Thomas
Thanks so much for any help in advance,
Thomas
Burning Brakes
Joined: Nov 2002
Posts: 807
Likes: 21
From: Los Altos CA
Originally Posted by Sully1882
ok ... then what is the correct way of diagnosing this problem or should I just replace the switch ?
Thanks so much for any help in advance,
Thomas
Thanks so much for any help in advance,
Thomas
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Racer
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Would an overcharge/undercharge of R134a cause the same problem(freezing)? Seems the R134a systems are much more sensitive than the R12. You just can't throw in a can of "freon" with the R134a. Ounces of R134a can make a big difference in performance either way.