I was just informed that the 07 5.9L does not have a relay for the AC compressor. Well crap no relay. I was really hoping it had a relay, even the napa store said it had a relay from looking what they had documented on their computers. I have my wiring diagram here and have checked both fuses for the AC system, both look good. When I press the switch for the AC in the cab my AC compressor will engage 3 separate times very briefly. Then it the compressor stays shut off completely.

When I jump out the compressor it works like a champ. So I thought it was just the button of the whole electronics panel in the cab. Well I pulled the panel out of my truck and put it in my buddies, and the panel worked just fine. I have also replaced the pressure switch on the compressor and have tested the temp. switch on the coils.

My freon levels are good. When I put a gauge on the system I had 100lbs on each side w/ the compressor off. Can someone help me out w/ this.

 

what were the pressures with it trying to run? what was the outside temperature when you got the 100 psi reading?

 

I have not taken the pressures while I have had the compressor jumped out. However, when the compressor was not engaged both low and high pressure were equal @ 100 lbs. The outside temp. was about 83 or so. Thanks for your help.

 

i had a similar problem with the AC not working on my 97 and it ended up being a fuse in the fuse box under the hood i think it said horn or something like that a guy at the shop found the problem..but it was not for the AC at all so you might want to check all your fuses in your relay box for the time it takes ?? i have no idea why it is like that and the horn was working when that fuse was blown as well ...just trying to help passing on what had happened to me ...

 

try to jump it and get a pressure reading, when you got the 100psi reading, was the engine warm, or was everything room temp?

 

98 Dakota, I will check all my fuses today. The two that are listed in the wiring diagram look good, but I will check the rest.

dodgetrucker, I will jump out the compressor again and then get a pressure reading and report back. When I got the 100 psi reading the pickup was cooled down I believe. When doing pressure readings on your AC should the automobile be at operating temp. or is it just something that you have to take into account when reading your gauges?

Thanks

 

temp plays a big part in a/c pressures, if everything is at room temp, the pressure should be about the same pressure as temp, but it could still have a low charge, with that reading, more pressure could indicate an overcharge, has and freon been added too the system, it does almost sound like it could be overcharged, but really need to get a reading while operating, it could be a 100 different things...