Looking forward to warmer weather I need to get the a/c checked out. As of now, the compressor will not kick on. All controls seem to be working. What's involved in checking out the cooling system? Can my system be converted from the R-12 type refrigerant to the R-134a type? I've heard the R-12 is pretty expensive. I haven't had to have an a/c system charged lately. Thanks.

 

The compressor will not kick on if the system is low on refrigerant. Yes, R12 is expensive, if you can even find it. It's pretty easy to convert to R134a. It does not cool as well in a system that was designed for R12, but it works.

 

Alabass is correct, the compresser won't work without a charge.
I did the conversion to 134 on my truck and the temp it blows now is a negligable difference from R12. I think its blowing at 60 degrees instead of 58.

 

I had mine re-charged about 5 years ago. The R12 was like $50 a pound then, I can only imagine what it would be now.

 

I'm working on OCRing a manual that describes how & why to convert to R-134a, and also how to diagnose any refrigerant system. When it's done, I'll make it available, but it's still a few weeks off.

You can get a single low-pressure gauge from Wal-Mart or a parts store to see if you still have any in your truck. If it's below 22psi with the engine off, the compressor will never start. If it's below ~80psi, the compressor will cycle.

You can convert, but don't use a kit - they don't contain the right viscosity of oil for Ford compressors and they don't remove the old mineral oil, which isn't compatible with R-134a. Open the system, remove the accumulator & orifice tube, pour flush into each hose & component (except the accumulator), blow it all out, replace the orifice tube (with a red one), the accumulator/dryer, and any questionable O-rings. Pour half the new oil into the compressor & the other half into the new accumulator. As soon as the new accumulator is installed, the system needs to be evacuated and checked for leaks. After that, it can be charged with refrigerant.

 

Before doing the change over to r134 consider replacing the hoses and acccumulator, small parts like O rings. Also, (I am still trying to find the right equipment) a total super flush of the A/C system. Clean it up while doing the change over. The A/C chemicals to not like each other. Also, any worn damaged parts should be replaced.
R-12....About $1400 for a 30#, legally. Lots more on the blackmarket.
Bruce (Big Red Bronco, needs A/C system rebuit)

 

A simple check of the AC-cycling switch is what I'd do first. Then, if it doesn't work, your probably low on charge and should consider converting to the new system. I changed over 2 years ago, and my compressor quit working this summer. Changed the switch and it works fine to this day. MY Z-71 would go through 2-3 switches per year