1979porsche911

Hello i have a 2000 mercedes e 320 that got me confused, the a/c freon was low, i tried to recharge but it only took a very little freon, also the low side read 50 psi, and it only took a little bit freon and blowing hot air, compressor did click on but not cold, and condensor fan is good, clutch is good, so my question is how do i check the compressor compression because i think its bad ,but i dont know how to check it without taken it off the car, thank you for your time.

bbirdwell

Go into diagnostic mode on the air conditioning control panel. It will give you a readout of every sensor to include temperatures pressures, etc. Don't forget to monitor each one as I found an intermittent on the EVAP core temperature sensor that would read accurately and then a few minutes later it would read out 149° and the AC system would shut off as it saw it as a fault in the system.
Do not go throwing parts at the car until you've had a chance to diagnose the system. Do a search and you will find instructions. I'm not at home so I cannot post those instructions at this time.
Try something along the line of "AAC diagnostic mode".
Edit: the AC compressor uses a swash plate to control the pressures. It is not a standard clutch type. Do an internet search and you'll find the difference.

bicylindrico

If the EC little LED stays lit up then it has detected a low freon level and will not engage the compressor again to accept a freon charge until the fault is cleared