Hey guys, it's been a while for me here. Here's the thing. My wife's 2003 Durango was running AC just fine, but she was complaining about it being a little warm. System was always one, never cycled off. So we went to the auto parts store about a week ago, and bought a can of refrigerant. I used the gauge to see where it was, based of outside temp it was really low, 30psi. The bottle said it should be at 45psi. So i started cranking in some refrigerant, after a few shakes and stops it wasn't going up in pressure much. Then all of a suddend it shuts off and pressure goes up to about 95spi.

Started cycling on and off without pulling the pressure down alot. Now when it's idling, and cooled down, it's at 35psi and blowing super cold no problems. as soon as you start driving it cycles off and on, blowing hot air. Can anyone tell me what happend? My wife is pissed that it's not working at all now. I'm totally confused what went wrong. It can idle up to operating temperature and blow ice cold, but as soon as we start driving, shuts off and cycles constantly.

Thanks in advance for any help!

 

Clogged condensor, orifice, etc. Time to have the AC system serviced.

 

Those cans with the little gauges are junk. You can NOT judge what's going on in the system with just a gauge on the low side of the system. You probably have it overfilled now and need to have it drained a refilled by a shop. Hopefully there was none of that stopleak junk in the can you used, otherwise no shop will ever hook their machine up to it.

 

Well I dont understand how it can idle and be ice cold almost indefinably, but as soon as you start driving it quits. What happened when I charged it? I didnt buy a super big can, just one of the 12oz cans, and it barely used half of it.

 

The compressor changes speed with the engine. That could be causing enough pressure on the high side to trip one of the pressure switches.

 

Wouldn't dropping back to idle speed let it reengage the compressor? The low side still doesn't show any high readings, even when not pumping.

 

The low side is under suction, so it's normally low pressure that trips it off. The gauges on those cans are complete garbage though. You either need to spend $50 or so on a set of A/C manifold gauges so you can see what's going on with both the high and low side, or take it to a shop that can check it.

Doing some research before you dive into messing with the A/C would be a good idea too. I thin EricTheCarGuy did a good job explaining things.
Manifold gauges (this ones come with r134a couplers that some don't)

 

Yes... very informative video! Doesnt look too difficult to do. Problem I have now is my system is full of refrigerant. Can I have a shop just evacuate the system only for me?

 

Provided you don't have any stop leak in the system yes. Call around, some shops might even do it for free since they are getting refrigerant that they can recycle from you.

 

Took it to pepboys. Turns out i over charged it. Works perfect again! Thanks for all the help and sugestions guys. I learned a little bit more about AC systems with this thread. You guys rock!