A/C Compressor Not Getting Power.....WHY??

[PaulJohnson]

2005 Dodge SLT It was in a flood got it up and going and everything is working now except my A/C. The truck has 350 miles on it now. I broke the a/c apart at the compressor and at the condensor to remove the engine, I put the engine back in and hooked all the a/c connection back up, and put the correct freon charge back in (1lb. 14oz. ). I nocticed then that it was taken a longer than usual time to put the freon back in. The compressor wasn't staying on but 5 or so seconds at a time. Drove the truck and the a/c wasn't cooling very good at all. Then stop working all together. When the compressor is on the a/c works great. Check for power at the compressor and there was none. Replaced pressure switch on the high pressure line, still no power to compressor. Replaced the a/c controls in the dash from a donor truck, still no power at compressor. Fuse is good in distribution box, swap a/c relay. Still no power. Really don't want to get raped by the dealer. What else can I check? My manual says to check a evaporator temp sensor but I think that involves removing the HVAC . Please Help!

 

[B.G. Smith]

The compressor is cycled by the switch mounted in the side of the receiver dryer (the small tank near the firewall). It should come on (with the engine running and system turned on) at around 45# and off at around 25#. The switch may be bad or you may have lost some of the charge. Unplug the wires to the switch and bypass the switch with a bent paper clip or other and see if this makes the compressor run. If it does then you are either low on refrigerant or the switch is bad. bg

 

[PaulJohnson]

I don't have a switch (low pressure switch) in my dryer... ... I only have the switch located on the high pressure line. That is the one I replaced, is there some where else the low pressure switch would be located?

 

[Matt400]

Aside from the A/C trouble I would be concerned about future electrical troubles yet to surface as corrosion starts to grow on other connectors.

Since a flood vehicle is a total for this reason, is it one you bought as a salvage/total?

 

[B.G. Smith]

I don't have a switch (low pressure switch) in my dryer... ... I only have the switch located on the high pressure line. That is the one I replaced, is there some where else the low pressure switch would be located?

Just went out and checked mine, no switch on drier either. My mistake. There is a switch on the rear of the compressor, that must be it. Pretty hard to get to get to unless you are lying on your back under the truck. Suction gage hookup would be easiest if you have access to gauges. bg

 

[PaulJohnson]

yes, i bought this truck as a salvage vehicle. I have replaced the entire electric system and all the wiring harness from a donor truck.

I will check that switch on the back of the compressor tonight, if I can't get it going I guess it will be off to the dealership tomorrow. Can't go without A/C here in Georgia very long.

 

[tempforce]

did you draw a vacuum on the system for 15 min, prior to refilling, if you did no problem. other wise you have moisture in the system and a low charge.