I did a search on this issue herein but came up with nothing. Here's the scenario: I turned on the truck and while it was idling I turned on the A/C. It wasn't extremely hot out, maybe 80 degrees. I had to wait for road work so I had the A/C on while idling for about 3 minutes. During this 3 min, the A/C didn't blow cold at all, then all of the sudden, I started hearing this hissing sound and a bunch of CO2 like vapor started coming from under the truck (I assumed it was Freon). As quick as it started, it stopped after about 30 seconds. We then started driving and the A/C worked fine and blew cold. Is there a high pressure relief on the Freon that somehow got set off somehow related to the fact that initially the A/C didn't blow cold at all when idling for 3 minutes? or other ideas?

 

Not quite the answer you're looking for but, yes, the compressor does have a blow off valve on the back of it. Once it blows you'll know it....it sounds like the compressor ate a bad batch of beans and had some serious gas....it's rather loud I'll promise you.....my neighbors all stared at me when mine "farted!!!" The only fix I found for mine was a new compressor.

I'm not sure about the hissing sound you heard but you can check for fan clutch engagement by turning on the system and covering the condensor with a blanket to simulate the system needing more air flow. If the fan comes on the clutch is good and you should start to try and diagnose other areas.

Also have your pressures checked and make sure they are where they need to be. Keep us posted.

 

Jhenson: Mine did sound like "it ate a bad batch or beans and had some serious gas" Did yours also let loose of a cloud of white vapor under the hood?

 

it could be a bad psi sensor and allowing the compressor to over pressurize the system also

 

johnr9q, yes I had a pretty good cloud of freon fog come out of the engine compartment along with A LOT of green dye that was shot into the system trying to find my leak. That dye makes an awful mess let me tell you. Went to O'Reillys and picked up a new compressor for $265 along with the cold line for around $30 I think. Went to an a/c shop and got a new dryer for $28 and then did the heater core block off trick with a ball valve and now my a/c blows around 38-40* out of the vents....Loving it!!!!