Okay...we've got the system charged to specs. It could also be the wiring from the relay to the clutch, the diode that prevents stray voltage induced from the clutch coil from traveling back to sensitive electronics, or the PCM itself. Try the easy test first. Put a VOM's test leads across the wire ...

I agree with Tim. In addition, whenever I see a question like yours, my response is to first and foremost, install the correct amount of refrigerant into the system that the manufacturer's specifications call for. The process involves recovering the refrigerant that's in the system now (or having a ...

I'm not surprised that you haven't received any replies to your latest posts. You seem to want to get deeply involved in refrigeration science and system-design, and that's fine. But I would hazard a guess that more than 99-percent of this Forum's members simply don't have the background for such a ...

This is a cobbled together system in an early Mustang. Which model year is this Mustang? I presume you've charged it with R-134a. Do you have the original R-12 specs for this car as a baseline? When first started at idle, the pressures settle to 25/150 on a 70F day and it blows 44ish out the vents....

With the multiple capabilities of your scan tool--probably more advanced than what the parts suppliers have--you might be able to identify the issue that's causing the no-shut-off problem and fix it yourself. Just replacing the switch with an OEM part might also correct it. Last resort is taking it ...

I mixed-up my responses. Apologies for the confusion. Getting back on topic, if the switch has failed "open" and needs to be replaced, it's possible that the system set a hidden trouble code that's causing the problem of not shutting off. Most parts outlets like AutoZone can scan it for yo...

You jumpered the thermal switch, which is prone to fail, and the system came on. Chances are, it's the switch that's defective.

Thanks very much for this info. Next recharge attempt forthcoming... I started reading about the VD compressors on the MACS website. It was enlightening, realizing that even when the clutch is turning it is operating at a smaller capacity and increases accordingly. Right. Even though the clutch is ...

Yes, hi side gained around 50 psi, max 60 or so, never exceeding the highest readings of the lo side. Cabin air never seemed to change temp throughout. Okay...you need to get the full, exact 32 ounces (net weight, not fluid ounces) of R-134a into the system before we can evaluate cooling performanc...

For peace of mind, I think buying a new line will be money well spent.