AC diagnostic help needed

[cbenowen]

I have an AC problem on my 99 LC that I cannot figure out.

AC works great.....blows cold but when car sits and idles for a couple minutes the AC light starts flashing and blows warm air. If I turn the AC off, turn off car and restart, turn the AC back on it blows cold again. It works great till the next time it idles for a few minutes. Then I go through the process again.

The system has no leaks and is charged correctly. Doesn't matter if rear AC is on or not.

Any suggestions on what it might be?

Thank you

 

[BullElk]

Any chance angine/coolant temp is getting too high?

 

[cbenowen]

It's the same as it's always been. If I start the car and try to cool it off before I get in, it will shut off in about 2 minutes. well before the car get to temperture

 

[Benjamin Ebrahim]

I'd check your freon pressures, same thing happened to my 2001 and a 12-oz can of R134a fixed it

 

[vcheng]

Scan it for any set DTCs.

 

[cbenowen]

I'd check your freon pressures, same thing happened to my 2001 and a 12-oz can of R134a fixed it

I had it checked and the pressures were fine. Everything was normal.

 

[cbenowen]

Scan it for any set DTCs.

Thanks. I'll scan it and see if anything shows up.

 

[vcheng]

Thanks. I'll scan it and see if anything shows up.

It is a good place to start, far better than just throwing parts at it.

 

[1972FJ55]

That compressor has a speed sensor in it that sends the compressor rpm to the computer that compares the engine rpm with the compressor rpm. If the is a difference between them that is outside the parameters, the computer thinks the compressor is locking up and shuts it off. Typically, it just needs a new belt or the belt tensioned.

 

[dwh13]

Mine has had the same issue on and off for a few months now. I have a small leak at the condenser, so a quick charge with refrigerant and she's good for about 5,000 miles.

 

[vcheng]

Mine has had the same issue on and off for a few months now. I have a small leak at the condenser, so a quick charge with refrigerant and she's good for about 5,000 miles.

Just be careful as over the long run, you will also lose lubricating oil required for the compressor. The replacement can should be of a type that includes the correct PAG oil, if you want to carry on this practice over the longer term.

 

[dwh13]

Just be careful as over the long run, you will also lose lubricating oil required for the compressor. The replacement can should be of a type that includes the correct PAG oil, if you want to carry on this practice over the longer term.

Yeah, definitely not advocating this over the long term. Just a stop gap until I recover from some of my other maintenance costs