Well just joined the forum.. And was hoping for some help... I have a 2001 dodge ram(5.9L ,auto) I just purchased.. Charged the A/C last week put 32oz of r134 and it works great thermometer reads 34F at the duct...Now here is the problem.. the A/C has developed a mind of its own.. it will just shut off(compressor clutch that is)..It will do it when I put a load on the engine (LIKE PASSING ANOTHER CAR) or if I manualy shut it off it will not turn back on until I shut the car off and let it sit for a few hrs.. The pressure on the low side 30-35...(cheap gauge that comes with recharge kit not sure of accuracy)...I have tried jumping both the high pressure cut off and the low pressure switch ..relay is working properly.. still the compressor clutch won't engage.. Any thoughts???? and does anyone know if the computer has any control over that circuit. thanks in advance..

 

anyone have any ideas

 

The PCM has no control over the AC. And for safety reasons I don't recommend jumping the high side switch. The other prob is the cheapo gauge. You need a good set and that will tell you what the low and high side readings are. And if you are jumping the switches and it does not turn on, that tells me something may be wrong with the compressor or clutch. Does it still work after letting it sit? And you tried jumping during this cool down period, or does it not work at all now? Your description is kind of confusing.

 

Yes it still works after I let it sit for 15-2hrs(depends on when the gremlins decide to relinquish control).. then it works great.. no signal just stops or if I shut it off it wont start until its good and ready and it doesn't do it al the time...Very random.. I can feel the relay click but the compressor refuses to comply... I did steam the engine about a week ago.. wonder if something could still be wet.. those weather packs conector seem to hold the weather pretty good.. so what do you think.. thanks in advance

 

The relay clicking does not mean it's good for one thing. And without knowing what the real pressures are, it's kind of hard to say anything along those lines. And how do you know the compressor shut's off when you are passing someone? Are you sure it's not the blend door, and some kind of vaccum issue is not present?

 

Zman.. I noticed that if the a/c is running and I give it the long toe(step on the gas hard) after I slow down the A/c clutch has stopped... I have even changed out the relay with the security relay.. Same part #... still won't work.. I just got back from running an erand a/c was blowing cold gave it the long toe n the entrance ramp to the highway.. Next thing hot air.. pulled over checked compressor clutch not engaging... I can bet that in about an hr I can go outside and it will work fine..Also Zman would the blend door effect the compresor clutch.. In the wiring diagram in the hayes manual... The pcm does seem to control the AC relay... Again any and all help would be appreciated.. Thank you

 

Since you confirmed the clutch is not going on, forget the blend door. Does the clutch make any unusual noise when it's running? Remove the belt and see if it has any excessive play. And your right about the pcm. But all it does is activate the relay when the **** on the dash tells it to and controls the IAC to keep the idle up when the ac is on. I don't see what that has to do with getting on the gas.

 

is your problem with teh vacumm closing the switch and changing the air flow to the windshield?

I think I read somewhere that a faulty water temp sensor would tell the A/C to shut down for saftey reasons. My a/c starts cold but after a time period is will turn warm. If I let the truck sit for a few hours I will once again have A/C for about 10-15minutes. It will do this all year. I do have a slow leak.

 

Your orifice tube may be slightly clogged. That could be why it works sometimes and not others. When too much pressure is trying to get through (at high speeds) it can't get through and the system shuts down. After a while, the pressure settles, and it will work again. These trucks have accumulators, and therefor an orifice tube, not an expansion valve.

 

Hello. Just joined as well. I have the same symptoms speedjester is describing in my '97 Ram 5.9L gas. A/C compressor quits at random. Drove from DC to Texas and the compressor would work fine until I pulled over for gas, when I would start it back up...A/C wasn't engaged and hot air was blowing. Only happened 4 times in a week, so no regularity to the occurence. I would turn the system off for 15 mins while driving, then it would work again. In TX, I bought a H/L pressure gauge set and both sides measured 5-10 psi high @ 1000rpm for the given external temperatures in the repair manual. Took it to the A/C shop, they could not repeat the problem. Said they purged the system, measured, and found that the freon was "quite low. They recharged it, added dye and oil, and the A/C worked perfectly with no leaks all the way to the California desert. Today it started again (2 weeks after recharge). Hot day (110 degrees), drove to the store (~5miles) got out, came back and the A/C compressor wouldnt engage. That was two hours ago...just started it and its blowing cold again. Haven't tried the long toe technique, but will do tomorrow.