TSB LTB00134 is for a different issue (odor), but the fix is to reconfigure the A/C Control Module which might be a generic fix for other symptoms, as well. Let me know if you don't already have this TSB and I will post it.

 

Please do. Thanks.

 

Attached.

 

I tried this and it did not help. SDD reported no HVAC errors. Then I checked the refrigerant and it is empty again. It's going to the shop on the 25th. Everything else is fine, engine still running like an old school sewing machine at 183k miles.

 

The standard process for detecting leaks (oil, trans, power steering, refrig) is to add flourescent dye and inspect with a UV flashlight. It's easier to do this for oil and power steering because you have a convenient fill cap to pour the dye into.

There are a bunch of Youtube videos describing the process for A/C and it's a little more involved, but not too bad. Have you considered giving that a shot?

 

I ​know that. Hard to do if the leak is behind the firewall.

 

What makes you think the leak is on the low side, behind the firewall? If you're lucky it's on the high side so the dash doesn't have to be pulled.

 

No dye anywhere on the high side, that I can see.

 

Ugh. Well, that puts a point on it.

If the shop is going to remove the dash, you might want to ensure they have access to replacement parts (evaporator, expansion valve) before they start the disassembly. With the current parts shortage, you don't want your ride to be sitting apart for weeks or longer until parts are available.

 

Good point. Also, they may find dye on the high side that I missed. I hope.