2manykids

A/C is all charged up, blowing nice cold air, start off down the highway at cruising speed, A/C starts warming up. I get off the expressway and start slowing down, the A/C starts to work great again. Is there a pressure switch or something that is bad? Seams that when the RPM's are up for a period of time, it kicks the compressor off. Any suggestions would be appreciated.

Clunk

My '92 used to do that too. At speed, I could cut it off for a coupla minutes and when I turned it back on, it'd be ok.
Whenever I'd stop, condensed water would run out in a steady stream for a few seconds out the rubber doodad then just drip for a coupla minutes. The area inside the rubber doodad was clear of any debris.
Do you think air pressure at the doodad at speed was greater than the weight of water at that area? Maybe a drain line glued onto the thing?

Stamey

Can you hear the engine fan blowing when the AC warms up? I ask because I am wondering if the clutch is bad, and staying engaged all the time, then when you have speed up, it is actually slowing down the air flow through the radiator, condenor, intercooler, because it isn't turning fast enough at highway speeds.

All I can think of, with what you have described.

Chris

I PASS GAS

Are you SURE it is charged up enough? If it is under chaged, it will cool pretty good. However, as soon as you get on the gas, the low side drops below what the shut-off allows and the clutch disengages. The low side at idle should be somewhere around 40 psi. 18-20 is the low pressure cut off on the suction side, so if it's hovering right above that, you are undercharged.

For this reason, I am considering putting a light in the dash wired to the a/c clutch to monitor when it is engaging.

2manykids

Today, A/C worked just dandy. I started off with the defroster on, then switched over to A/C after I was on the expressway. A/C blew cold all the way to work.

popeyesides

Yup mine has been doing same thing,I replaced compressor and clutch and It still did it.Yesterday I replaced high pressure switch and it now works perfect.I guess it was a waste of $500 but at least I know I have a good compressor .The switch was $21 at dealer.I have 89,000 on the truck and bought it new 6 years ago,so thats not much to spend after 6 years....

2manykids

Great, now that its narrowed down to the high pressure switch, where/what is it? Sorry for sounding dumb, but A/C systems aren't my thing. Still trying to figure out exactly what my "thing" is.

popeyesides

High pressure switch is on passenger side ,near firewalll,mounted on black bottlle(top).with electrical plug.

2manykids

Thanks, do I need to drain the system and recharge? or can I just swap it out?

CTD NUT

The low pressure switch is the one on the accumulator/dryer (black bottle).....the high pressure switch is on the pressure line coming out the back of the compressor and right beside the intercooler boot.......and yes, you can change the pressure switches without having to drain and recharge the system.....there are shrader valves beneath the switches that prevent refridgerant loss when the switch is removed.

2manykids

Thanks for all the help guys. I'll be changing it this weekend.

Stamey

Well hold on a sec. Which switch, by location, did you change, Popeyesides? As CTD Nut said, the low pressure switch is on the dyer. Did you replace that one or the one behind the compressor?

Chris

popeyesides

Howdy,I guess I did replaced the low pressure from what everyone is saying,I told Dodge parts man that I need high pressure switch,but when I went to replace it behind compressor it was wrong one,so It fit on the dryer,and I don't really know much about A/C.But If It makes any sense the low pressure switch took care of my problem,now I wonder if I should replace the REAL high pressure switch too..Any info would be helpful,sorry I did not respond sooner,we just got back from SeaWorld....