AC issue... not sure exactly what.

Joined
Jan 18, 2003
Messages
320
Location
Dallas, TX
My pickup's AC has started doing something a bit strange- it'll run cold about 4/5 of the time, and then for no reason that I can tell, shift to blowing tepid/warm air for a minute or so, then it goes back to blowing good and cold for another 4-5 minutes.

I'm not low on refrigerant according to the little gauge thing that I have left over from when my previous truck needed the occasional recharge. The needle's squarely in the green range.

I'm not sure what it might be. I'm not overly concerned in that it still works and it's not uncomfortable when it blows not-cold, but I am curious if it's something that'll get worse, or just stay as it is. The truck's a 2005 and never had any kind of AC work done- it's always worked like gangbusters until now.
 
Take a thermometer stick on the center vent and close recirculate. You should see close to low 40's on the temp, if higher you are low.

If you got a cabin filter make sure is clean before doing the temp check.
 
I had a similar thing happening with my system. It seemed like it was especially under load, either accelerating to get on the freeway or going up a very steep hill. There were two things wrong with my system, the clutch was literally falling halfway off the compressor and I had a leak, so I was definitely low on refrigerant.

So yeah, as KrisZ says, check your clutch. And as Chris142 says, your gauge from your recharge canister, if that's what you're using, is useless because it only looks at lowside pressure. You'd have to get a manifold gauge set and check both high side and low side pressure together at the correct rpm and look up the specs for your car on what the pressures are supposed to be, at a particular outdoor temperature. It's not a simple thing to figure out if you're low.

That was my experience. I'm not an expert, so maybe it could also be other things.
 
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