I was at the Valair Truck Pull on Saturday. We ran the A/C all day, even during the Drag Racing. Well I made a pass with the A/C on, and at the end of the pass it quite. No sign of freon anywhere, no smell, no smoke, no drips. I crawled under the truck, and the clutch on the compressor is not engaging. I disconnected the plug going to the compressor, and checked voltage, with the snowflake switch on it reads 13-14 volts. But when you turn it off it still reads 10+ volts. i figured it would read 0. All help will be greatly appreciated.

 

The ECM controls the a/c ground, so there is power there all the time. Not 100% positive but close.

 

Well thats not good, a buddy of mine has the truck. we measured his, and when he turned his switch off there was no voltage.

 

If its getting 14 volts then is should be kicking the clutch on, if its not, I would say you have an issue with the clutch, you could try powering the clutch from the battery with a fuse just to make sure the clutch is good.

 

Stick a test light to it, a lot of times you can find odd ball issues where you have voltage but the wire will not supply the amperage that is needed to run the coil. If it will run the test light I would even go and get some bulb sockets and wire up a 5 or 6 amp test light myself.

The next thing to do if you are sure that you are getting amperage to it is to power it with a battery, if it will not kick in by its self tap it with a small hammer to see if it will kick in then.

 

After thinking about this it may need some calcification, the PCM controls the A/C RELAY GROUND. Then the relay would power the A/C clutch. So the button you press is not hard wired to to the relay or A/C clutch. The PCM decides when and if it will do as you have asked it to. All other conditions must be met before the PCM will turn on the A/C relay.

So if you are getting 12volts to the clutch, this eliminates allot of other problems. At that point I would put a ohm meter on the clutch to see what is going on.

 

I put an ohm meter on the two prongs at the plug on the clutch side. It was reading some resistance. I also ohm the negative side on the plug coming from the TIPM, one probe on the plug, one on the frame of the truck. it shows direct short. where would I find the A/C relay. maybe it is bad.
Thanks again for the help.

 

Look in the power fuse box under the hood. Left side I think. It's raining cats and dogs outside or I would go look and tell you.

 

On your clutch, remove plug, with jumper wires apply power 12 v+ to one side ,then apply ground to the other, it should not matter which way you apply wires , the clutch will click (engage). If not then clutck is bad. Follow this link for wireing info.http://www.dodge.com/bodybuilder/2007/intro.pdf

 

Thanks to all, I had to work late tonight, but tommorow i will give the clutch a jolt of power.

 

Thanks to everyone for the info, help. It was the clutch on the compressor. I got a new compressor, and had it installed. works great now. Thanks again.