My XJS 1994 V12 AC has leaked out freon and does not cool at all....not a big problem for me as I'm in the NC mountains with top down .....but now my heater will not work either.....does the AC system have anything to do with my heater not working

 

The heat should work just fine with no freon in the system. As a search hint for chasing leaks, on my 94 V12 the leak was at the fill port itself. It's a standard GM part. High side is AC Delco 155438

 

Are your ventilation fans working? The heater valve normally fails open, but can get stuck while pulled shut via vacuum. The core could block up but its not common. Thats all I can think of.

I would reverse flush the core and valve into a bucket and inspect what comes out. Sort of a core sample for the cooling system. If its flowing through the valve and the core you'll have heat. Plenty of it.

 

With no gas in the system I would disconnect the AC compressor clutch or you might find the compressor seizes up.

On the heat issue my first suspect would be the heater tap it's not uncommon for these to jam open or closed. It is on the fire wall and you can test it with a syringe by sucking on the vacuum line it should close.

 

No need, there is a low pressure protection switch. If the system pressure is below 29 psi the clutch will not engage.

 

In theory.

 

Mine didn't work and the compressor graunched and seized. sparks and the whole deal. AC compressor in the bin.

 

If it's like mine,,, check to see if the temp control knob is DEPRESSED or EXTENDED. I was surprised to learn that the knob pushed in and out for a manual and auto operating mode.

If it's in AUTO mode (I still don't know if that's with dial DEPRESSED or EXTENDED, lol - just got her on the road after a ton of work) and the dial is turned to mid temps or,,, no heat.

 

Was yours the A6 compressor or a Sanden? Different control strategies for each of them. The later Sanden control is a dual mode switch that removes power to the compressor clutch relay for either high or low pressure, rather than the older superheat in the back of the A6.