A/C stopped blowing cold at idle

CurtisF · Jun 3, 2011

It happened today, never did it before as the A/C has always blown cold no matter what. I had my truck idling as I was unhooking a trailer. Got in to move it and noticed the A/C started acting like it was as if I had it on vent. Got out, put the lock on the trailer, got in and started driving. As soon as I got moving it started blowing cold again. The whole time it was on max, with the fan turned at full blast. Didn't do it again the rest of the drive home, even sitting at stop lights and idling in the driveway.

I haven't messed with A/C on a vehicle in probably 12 years, and it was an old Firebird that had a leaking compressor. My truck has never done this before, so I'm looking to see what might be going on. I'm guessing it's low on refrigerant. If so, I'm looking at a possible leak. Any common leak points I should check out first? Truck is a 2002.

My luck, just as I get sh!t fixed and upgraded, something out of the blue pops up.

Lowdown89 · Jun 3, 2011

Have you checked the gap in the clutch in the AC compressor? Here is a write up on it and has fixed many a truck from intermittent AC problems

http://springerpop.net/F350/air_gap.html

crowz · Jun 3, 2011

:whs:

G Racing · Jun 3, 2011

You could have a vacuum leak to the hvac controls.

crowz · Jun 3, 2011

Shouldnt effect it at idle since its an electric vacuum pump on his truck.

Tom S · Jun 3, 2011

Even one of those cheap AC guages from the Autoparts store makes it easy to see if you are seriously low on refrigerant.

CurtisF · Jun 3, 2011

Lowdown89 said:
Have you checked the gap in the clutch in the AC compressor? Here is a write up on it and has fixed many a truck from intermittent AC problems

http://springerpop.net/F350/air_gap.html

That I had not seen before. I will certainly check that out on my truck. It's quick, it's easy.... I like it. Gonna have to get some feeler gauges, but that's fine... they're cheap enough. Thanks for the link :thumbup:

gracing said:
You could have a vacuum leak to the hvac controls.

The only thing there is it's not going from vent to defrost. I've had vacuum leaks before, and it always defaulted to defrost. But in this case, it just started blowing warm. Plus I can still move it to defrost, floor, vents, etc, and it works perfectly fine there.

Tom S said:
Even one of those cheap AC guages from the Autoparts store makes it easy to see if you are seriously low on refrigerant.

Yeah, I may do that if nothing happens with checking the compressor clutch gap.

I appreciate the help guys.

Early99strokin · Jun 3, 2011

Check your fan clutch. If it isn't pulling enough air over the condenser it will blow warm air.

SkySki Jason · Jun 3, 2011

Could be fan clutch or compressor clutch - but I would pull the grill and inspect the condenser for debris FIRST. It doesn't take alot of bugs or mud (or bent fins!) to significantly reduce airflow and subsequently parked A/C performance.

If its low on refrigerant, the compressor will cycle on/off alot...

CurtisF · Jun 3, 2011

SkySki Jason said:
Could be fan clutch or compressor clutch - but I would pull the grill and inspect the condenser for debris FIRST. It doesn't take alot of bugs or mud (or bent fins!) to significantly reduce airflow and subsequently parked A/C performance.

That's clean... at least mostly. Not enough for me to worry about. I've seen far worse.

SkySki Jason said:
If its low on refrigerant, the compressor will cycle on/off alot...

I was under the impression that it was the opposite.... low on refrigerant means the compressor would run longer before the clutch releases. If it's full, it cycles in shorter runs.

Unless I was told wrong years ago.

crowz · Jun 3, 2011

It goes both ways on the low freon. If its low but not too low it will run all the time and just not do as well as it should.

If its very low the low pressure switch will cause it to cycle like crazy, again not cooling worth a flip.

Tom S · Jun 3, 2011

If they are really low most Fords I have been around run the compressor for a few seconds then it cuts out. The cycle they repeats over and over and over.