Expansion valve is easy peasy. If you’re going to replace it, you’ll lose all the refrigerant.

It seemed to solve my problem where most times I’d get cool air, but sometimes I didn’t. Never could get it cold.

Now it’s cold.

If you have no leak, then the only other part I’d consider replacing is the drier. That is also easy.

Let me know if you need any details on changing the expansion valve.

In the meantime, if you want to check the pressure valve, which is also easy to replace with the refrigerant evacuated, run the AC and unplug it. You hear a click at the compressor. Plug it back in, and you’ll hear a click at the compressor again. It’s not common, but certainly possible.

 

Glad to hear replacing the expansion valve is doable. Access is the concern on the 4.0. I was bothered by the ability to "hold"it secure and not damage the low pressure line going through dash into the evaporator....is there a risk of it turning? Thanks for your response...Gerry

 

Again, regarding our 1994 XJS, does anyone know of a source where we can obtain electrical schematics for this model that include detail on the air conditioner wiring? The AC compressor isn't engaging but with known freon content. We need to know which switches and ideally where they are located that prevent engagement. All advice is appreciated.
Gerry B.

 

jagrepair.com

I'm not really sure what, "The AC compressor isn't engaging but with known freon content", means.

The expansion valve is over by the firewall. Access is good. I think you should take a look at this project first. If you take a look, you'll find that there isn't any risk if turning. You're replacing a rectangular block of aluminum that have two pipes entering and exiting. You can't even mix up the way the block goes in since the two pipes going in and out are different sizes! The torx screws that hold it in place, also apply the pressure at the ends of the pipes to keep them locked in place. There's a hole for that pressure plate that only exists on one side of the expansion valve, again, making it impossible for you to install it the wrong way!

Please make sure you have green o-rings for hvac available. You'll want to replace any you come across. There will be at least four that will need replacing. A standard HNBR o-ring kit from Harbor Freight will have what you need. You can also order a kit from Amazon, etc as well.