C5 Diag

My 01 with dual climate control has the AC light on even with 80 degrees set into the controls on a 50 degree day when it's in Auto. I also confirmed that the AC clutch is engaged when this occurs. The defrost is NOT selected either...when I turn the AC light off it kicks the climate control out of auto into manual operation...I read the owners manual front to back on the AC system and can't figure out why this is happening...any help out there anyone ??

Bill Vett

It does that to remove moisture in the air inside the car so the windows don't fog up.

coia96vette

Turn your setting control off of auto and put it on up and down. When the setting is on auto it will run the ac to help get the moisture out.

Borntorun04/17

Noticed same thing when I took car out for ride before putting car in for it's winter nap. Never noticed it before, but I don't run the heater to often. Thanks for post and answers.

C5 Diag

Well I'll check when the temp gets to 35-40 degrees when the AC should not be operating...if it still does I have problems !!

jcgunn

The window defrost setting will also aways force the A/C compressor ON.

Bill Vett

It will do it and you Don't have a problem. The system puts the AC on even if it requires heat, as I said it removes the moisture ......you don't have a problem.

Lee DeRaud

And looking at the schematics etc in the FSM, just because the button light is on doesn't mean the compressor clutch is engaged: that's controlled by a pressure switch as well as the control unit, with some additional inputs from the PCM.

If the clutch is working (i.e. it disengages when you switch the A/C off manually), but it stays on all the time otherwise, you may be low on refrigerant and it's not getting to the high-pressure cutoff limit.

C5 Diag

Thanks Bill,
Like I said it switches on and off (AC light on and off) when manual mode is selected and I verified this looking at the compressor clutch but always on in auto even if heat is selected I guess I'll check the refrigerant level !!

ztheusa

ALL GM cars have been like this for 30 years. Where have you been?

C5 Diag

Guessing from your remark I'd say you probably weren't even born yet or you were busy riding your Stingray.....with a banana seat...LOL !!!...my last GM product was a 1972 Z-28 Camaro... Enough said !!!

Vetteman Jack

At least now you know there is nothing wrong with your HVAC unit.

C5 Diag

Thanks gentlemen for all your input...thanks again !!