Hello all. I have a 99 Ram 1500 Sport with a 5.9L V8 Magnum engine. I have right at 188,000 miles and it is an AWESOME truck. I am currently having some A/C issues and have been told a couple of different things as to what it could be, but not quite sure what it is.

Facts:
The blower for my truck works just fine. However, the compressor itself never kicks on. I have checked the fuses and relay but they all check out fine. I checked the relay by swapping it with wiper relay and it didn't make a difference; wipers worked fine and compressor still not kicking on. I checked the connector wire going to the compressor and it is clean and secure. Last summer (2010) the A/C would work for the first 10min i was driving and then would stop. The only way I could get it work again was to let the truck get cold (but even that didn't work all the time). This summer it is completely out. I have had the refrigerant checked and it is good as well. High and low said were diagnosed to be fine. I'm really at a loss at the moment and not sure what else to look for. I went by a national auto-parts store and they suggested the A/C switch which they said was an inline switch.


Any help would be most appreciated. Thanks.

 

Does your horn work? (yes, this is relevant..... oddly enough.)

If the horn is fine, time to check the pressure switches. Low side switch is a common failure. Just unplug the switch, and jumper the terminals in the connector. If the compressor then works, replace the switch. (this assumes that your pressures are indeed good.)

 

Awesome....now, can you tell me where these pressure switches are? Unfortunately, I am not as good with vehicles as I am with computers

 

NVM....I found the low pressure switch. I attempted to jump them to together (I tried a paper clip and a wire) but it did not kick the compressor on. Just to make sure i did it right, i was supposed to jump the wire plugged into the switch and not the switch itself, right? Because i did not do that. I did, however have a problem finding the high pressure switch.

Thanks for your patients,

 

Yep, jumping the connector was correct.

Does your horn work?

 

First I would try to add some refrigerant to it and see if the compressor will then come on. Get a can with a gauge from your local auto parts store. If that doesn't work and jumping the switch didn't work your compressor might be bad.

 

do our trucks have both a high pressure limit switch (loc?) and a low pressure limit switch (on the accumulator?).

will either of them trip the compressor out?

 

Yep, we have both. And yes, they will.

 

high pressure is on the compressor and low pressure is on the accumulator, if he would let us know if his horn works, that could be the simple solution. The symptoms are the same and theres been 3 or 4 other people who had the same problem and it was the horn

 

Yes the horn works, my apologies....I will try jumping the high pressure switch today and let you know.