2nd Gen Non-Engine/Transmission Air conditioner troubleshooting help

[LCampbell]

A couple of days ago my air conditioner was working fine. Yesterday it wouldn't cool at all. The clutch seems to be working fine but the compressor keeps cycling on then off. It will run for a several seconds & then shuts off for a few seconds & then starts up again. The serpintine belt is tight & in good condition. The truck is an 02 2500 with an automatic trans. Does anyone have any suggestions. Thanks in advance.

 

[LHastings]

I think these truck have a low vacuum switch that is located near the firewall. I had a similar problem with a buick. It turned out to be the low vacuum switch. I jumpered the connector and the compressor ran and put out cold air so I replaced the switched.

 

[ttbird]

Sounds like your 134a is low. Needs charging. Parts stores sell hoses with gauges on it that connect to the low side line and taps the 134a can of freon. My 95's low side pressure is around 35 when cooling good. If you charge it and if it stops cooling quickly then it's leaking. Whole other problem, got to find leak. If you don't like messing around with unfamiliar stuff, find an automotive air conditioning guy and turn him loose but I bet it will cost alot. Finding a leak is a pain in the butt. If this just happened suddenly, then look for damage to hoses or condenser. If it has been getting worst slowly for awhile, then you may get away with charging it and it may last awhile. If you do decide to charge it, do it gradually and give it time to stabilize after each charge. Don't take low pressure above 35- 40. I could go on forever. Do some research and dive in. It's how I learned about it. Good luck.

 

[LCampbell]

I'm not sure if this changes the big picture any but today when I rode the truck In the Max AC setting the fan did not come on to the high setting. LHastings. Thanks for the info I'll scope it out. Ttbird. thanks if its a low charge than I'll have that done by a shop. The truck AC has never had a recharge since new.

 

[LCampbell]

Bought the hose with the gauge, a couple of cans of 134a & a 2oz. can of oil. The pressure in the system was low so I added the oil & a little over 1 can of 134a. Had to jumper the LP switch to get the compressor to run continously. The pressure is in the middle of the green zone (35#'s) now & it's cooling pretty good. Thanks again TTBIRD.

When I put it in MAX AC the fan still does not come on to the high setting. Any ideas as to what's going on there?