Another A/C problem

[Davidggriffith]

So my problem is this my ac blows ice cold for about 20 minutes and then it starts blowing warm air then it goes back to cold so I was watching the ac compressor and noticed that the ac clutch was engaged all the time and not cycling on off on off so I think the ac system is freezing up so what do I need to do to diagnos this problem is there a sensor that controls the ac compressor
Thanks for any help

 

[retorq]

There is an "anti icing" sensor that is supposed to be in the compressor, if that is missing or bad it will do what you describe.

 

[BRUTUS_T_HOG]

Without knowing what we are working on the best guess I could stay is a bad cycling switch. Get an OEM switch, the cheap ones are bad out of the box

 

[Davidggriffith]

It's a 99 tahoe 4 door lt with rear air

 

[Y2KpewterZ]

Had the same problem. Shop couldnt even figure it out. Almost $800 later (i needed the lines replaced since they leaked anyways) but turns out the relay would 'over heat' and would turn itself, thus cutting the compressor off.

 

[SunlitComet]

There is an "anti icing" sensor that is supposed to be in the compressor, if that is missing or bad it will do what you describe.

Who gave you that idea?

 

[retorq]

There is a sensor on the back of the AC compressor when it's bad it will allow it to run all the time thus ICING over. It's common for people in warmer climates to bypass that and get their AC working, if that's bypassed in a colder climate it will ice over.

 

[SunlitComet]

Cycling switch foo plus a over-pressure cut out then of course your safety relief to prevent explosions.

And watch your language. I have no tolerance for derogatory remarks from or to anyone. Period.

 

[retorq]

LOL Ohh no ... good to know. \m/

 

[willxfs]

My ac relay switch under the hood got stuck in the on position. Would keep the ac clutch engaged all the time. After 30 minutes the ac would freeze up and quit working. It was also killing my battery sitting over night. Got lucky and identified the relay before having to bring it to a shop. Ten dollar fix.