Have a 1995 E320 AC will not bolw cold air. Check out compressor - it cuts on, fluid level (as per E320 book and it looks good. But the aux water pump seems to be too hot. Could this be the problem. The no cold air happened quick you have it then its gone.

Horace

 

have you ever replaced the refrigerant?

 

Sounds like the AC is good, but mixing in too much hot water. If the refrigerant suction line is cold (the large line leading from the firewall to the compressor) and no bubbles in the sight glass then your AC is fine.

Your aux pump/monovalve may be in need of replacement or you may have a control issue in the controller.It could even be a bad connection in the temp setpoint potentiometer. Try moving it up and down a few times. This controls the amount of heat that is mixed in. The AC is either activated to maintain a cold coil or it's not. It doesn't modulate but only cycles on the low pressure switch. The heat modulates, but I don't know if it uses a blending damper under the dash or uses the monovalve to control the amount of water through the heater core.

 

Refrigerant was replaced a few years ago when other owner hit something. Checked and suction line is not cold, problem? But the aux pump is still very hot.

 

It's probably low on refrigerant. What "fluid level" were you referring to?