The summer is rapidly approaching and I live in Florida, my 71' is finally road-worthy enough to be my daily and I need A/C! The truck is not an original A/C cab so I am determined to make my own setup. I'm a metal fabricator by trade so engine brackets and custom mounts for condenser and so on aren't an issue. My biggest hurdle will be understanding how the electrical side of this will work.
I have a universal under dash evaporator with fan and expansion valve that requires a single +12V connection. I have a single groove V-belt compressor with manifold (highside & lowside pressure sensors attached), condenser with electric pusher fan and new receiver/dryer. So all the hard parts are there... What I don't know is what the compressor side of the electrical circuit should look like. I assume I will need to run a heavy duty (30-50A) relay from the evaporator fan switch to the compressor circuit, but how do I tie in the pressure switches so the compressor will cycle properly?

Thanks in advance for helping eliminate Swamp Butt this year!

 

I'm running my from thermostat wire through the high & low pressure switch then to the compressor clutch wire. Like the old xmas tree lights once were.

If your going to be using r134a Freon you'll need a compressor design for that type of Freon since this r134a runs a higher high side pressure and a r12 compressor reed valves will not be able to handle the high psi for very long until it fails. And yes best to have push or puller fans for slow city driving so you keep cool air blowing. If no electric fans then you'll have poor city driving cooling.

Plus do not mix any different types of Freon's if you ever want to take it to a shop work on it as this the first thing a shop checks for comtamation. Like some guy put in r22 Propane and so on. They will mostly walk away and not service your vehicle.
As it would also comtamation there equipment.

Orich

 

Thanks for the insight! I found a connection on the evap. box coming from the temperature control, from what I understand I need to run that +12V feed to the lowside switch then to the highside switch and finally end at the compressor? I plan on using R134A as most shops are familiar with that.

 

Yeah that pretty much the same way I've got mine.

I like and use the r12 and do all my own work and have all the stuff evac. pump gauge manifold setup.

I have given my Son over in Las Vegas are 20'lbs of r12 evac pump an gauge setup for his daily driver a few yrs ago a 92 VW Golf or what ever it is.

I buy & pay for r12 at some here & there and car shows but not pay more then $20 bucks a can 14 oz.. Then sell it for 3 cans for $90 with a charging hose. I can always fine it.

It's about 7-$800+- here to change over to r134a when done right at a shop.

Orich