Suburban Atlanta

My 2002 Suburban 1500 2WD (110k mikes), with rear A/C lost all Air Conditoning cooling today. I was drivig up the road (clean paved city street) at maybe 20 mph, just starting off from a traffic light. Basic driving here. Nice and calm, when I heard a "ratcheting sound" in front of me, apparently in the engine compartment.

Windows were up and A/C was blowing cold on a 90-some degree afternoon. the air stopped cooling in a mater of seconds after the sound. Turned hot as outside air, perhaps a little more.

Never had an a/c fail so fast, and never heard a sound like that from any car ever.

Very strange... Any clues? Ever heard of this?

Suburban still ran fine... Was just crazy hot inside!

Thanks.

johntaps

Check Freon in the system and a/c compressor clutch. If both is fine then there is a restriction in the a/c system and the pressure on the compressor is too high.

Suburban Atlanta

On most cars, I'm aware of the compressor cycling. On my Suburban, I've never really been able to hear it or feel it kick in but I feel like I should hear it when I make a point to listen for it. The air has always been super cold, so I've had no concerns. I've had the car 3 or 4 years.

Checking as carefully as I can, I'm not hearing any sort of click for the compressor attempting to engage at all. This is starting to make me suspect that "ratchet" sound was a rapid on and off of the clutch a dozen or so times. Maybe this points to a clutch failure?

I may have to take this to the shop. Limited time and I hate dealing with air conditioning systems. Guess I could throw on a set of gauges first just to see the pressures.

Even if the charge is bad, shouldn't I hear a quick attempt for the a/c clutch to engage momentarily though? or will it ot even attempt to start the compressor of the pressure is out of range?

oldchevy

if the freon charge is low, it will cycle on and off. If the system has no freon, it will not attempt to cycle on and off. You can look at the clutch on the compressor and see if it is cycling, you don't have to listen for a sound.

kevinkpk

X2. If the clutch isn't engaging certainly could be the low pressure cutoff. What I would do, with system on, and running, unhook the plug from that switch, and jumper the plug wires to see if then the clutch will engage. If it does, service the freon. If it "ratchets", and dosen't engage, time for either a new compressor or clutch. You can also unplug the connector to the clutch check it for voltage with a voltmeter or test light.