Wiring for Air Conditioning without having ECM/PCM etc.

[crawler]

I'm building a toy (undisclosed chassis for the moment). Using a 95 2500 as a donor. How do I make all of the air conditioning system work without using the factory wiring harness or computers(gone before I go the donor truck. I can come up with all of the plugs that I need, but I would like to just eliminate the computer from having any control over the A/C system.



I don't know much about A/C systems so I don't know what all it needs to operate correctly. I assume that since the system has high and low pressure switches that it can be wired to work independent of any other vehicle components i. e. ECM.



Thanks,

Wes

 

[CumminsBurban]

You could look at wiring from a car built say in the 80's with air conditioning but no ecm. I currently have mine hard wired but only because I ran out of time and wanted to have a/c. I don't think it would be that hard. I would recommend getting a wiring schematic so that you could see what voltages were going through what wires and wire it that way.



CB

 

[TKingsbury]

Find a wiring diagram for an aftermarket system. They are wired very simple. You could just use the appropriate generic switches to make it work.

Travis. .

 

[JCalvin]

Would it also be possible to just use the stock ecm/pcm and let it run those accesories and just keep it away from the powertrain

 

[DKarvwnaris]

Would it also be possible to just use the stock ecm/pcm and let it run those accesories and just keep it away from the powertrain

All you have to do is provide power to the A/C compressor to make the system work. A simple switch on the dash will do this. For the protection of the compressor, I would wire in the high low safety switches to a simple relay that would require power from both high, low, and the power switch to energize the pump. I have done this for Jeeps before using mismatched automotive parts. The only thing I think you'll need to check on is the flaps to close off the different ducts in the dash which might not be an issue if you're looking to rebody it to something else.



You can find an ECM from any dodge truck to control the climate controls. PLenty of gas powered dodge with low miles sitting in junkyards with wasted drivetrains, interior plugs and harnesses are the same for this issue.

 

[tgbol]

Does your toy chassis have air? If so all you have to do is connect its compressor wire to the one on your engine. If it doesn't, track down an after market air set up and then hook it to your compressor. I wouldn't try to use the Dodge air system to many little things to install.

 

[MPalachuk]

Look into a trinary swith off of a big truck, It does the high and low protection all in one and it also has a side for a fan control if you put a electric fan on it. They are easy to wire and you can run the power threw them to a relay or not use a relay.

 

[tplewis]

i have just completed a cummins conversion in a 1995 chevy surburban that had a 454 i was worried to death about the ac working without the gm computer i took out all the wires from the existing harness that had to do with the ac alt oil sending unit and the blower motor and when i fired it up and charged the ac it worked fine the gm computer had one green wire going in it for the ac i assume it's function was to idle the engine up or down with the ac on it worked fine with it cut from the harness if you have any questions send a e-mail or call 8705542235tony lewis