Hi, I am trying to figure out whether my compressor is bad or not. I know it is not pumping from using a low side pressure guage, it looks like the clutch is engaged but I'm not sure. It appears that the end of the compressor is turning with the pulley weather the ac control is on or not. I even went as far as removing the control module from the dash, still looks like it's turning. Aren't there some MB models in which the compressor runs all of the time and you wouldn't be able to see if the compressor is operating or not? Thanks for any opinions.

The TXV could be bad/blocked. Read codes, preferably with XENTRY.

Thanks Chassis, I think if that were the case the suction pressure reading would be very low since the flow of refrigerant from the high side to the low side would be blocked. I'm wondering if the compressor is internally broken, I can't be sure unless I can determine if the clutch is engaged or not.

XENTRY will answer those questions.

If the clutch isn't engaging, then the compressor is most likely bad. I have one in the box right now.

I am not sure if the clutch is engaging, I tested with Xentry no issues. It appears you cannot force the clutch on and off with Xentry. On most cars you can see the middle of the compressor pulley rotating if the clutch is engaged and not turning if it is not. Is that the case with this compressor?

Yes, XENTRY can force the clutch on and off. I did it today. There may be something wrong with your XENTRY software or hardware (dongle+cable+MUX) connection.

Do a quick test of all modules. Then do a quick test of the air conditioning module. Then go into actuations and use all actuations available to confirm your XENTRY is functioning.

You can also try the old school method and listen for the clutch while someone manually turns the A/C button on and off.