Automotive Air Conditioning Information Forum

Vehicle: 1994 Range Rover Classic, TXV type AC, Sanden compressor, converted to R134a.
Background: Rebuilt AC with new TXV, drier, flush, R134a kit, new oil, dye, etc. Worked fine for 3 years or so. Drove it the next spring, no AC. No leaks detected, refilled. Leaked out in a few weeks, no more AC.

Now: Ignored for years and didn't run AC. Probably 8 years later, went to check it out, and it has about 20 PSI in it after all those years! But not quite enough to trigger the low pressure switch to turn on compressor. Smells like R134a. I see no evidence of any dye or oil anywhere, can't determine where it leaked.

1) Can I safely assume that if there is still some pressure after all those years that the leak must occur only at high pressure but not low, and condemn the compressor? A new Sanden designed for R134a is only $200 or so. I'm told that it is often the shaft seal on Sanden compressors a while (sometimes years) after switching to R134a. I think that this definitely tells me that condenser and evaporator are both OK or it would have been at atmospheric pressure with even the slightest leak in that many years.

2) Can I also assume that the drier is still OK given that there is still pressure?

Newbie here... THANK YOU!!!

You need to do a robust leak check. Using a MGS and both red and blue service hoses connected, puff in via the yellow service hose sufficient refrigerant till both high and low read about 20-25 psi. Use standard practice to prevent air from getting into system. Then using an electronic leak sniffer check all system components, especially fittings. To check the evap, go underneath car and insert sniffer hose into evap drain. This is far better than trying to remove the evap.
You should be able to find the leak.

“I'm told that it is often the shaft seal on Sanden compressors a while (sometimes years) after switching to R134a.”
I don’t know about that. However, the hardest part of any System to seal is the compressor shaft

Keep in mind that in an older system, their may still be “pressure in the system “ but it may only represent refrigerant that was dissolved into the oil, which is slowly being released from the oil. Then get back to us