A/C woes - Suggestions please
 

I have searched the archives but could not find an answer to my problem.

Car: 1986 300E
A/C: R-12 system

Problem – the A/C does not cool.

Here’s what I have observed so far:

• Compressor kicks in and doesn’t cut out.
• There is refrigerant flow – I can see it flow via the sight glass in the drier (when I turn off the A/C, there is no flow) – there are very few bubble – I can see liquid flowing
• The aspirator for cabin temperature is working (the little piece of paper I placed in the grill in the dome light stayed there)
• Turned the temperature wheel to Min and the fan comes on full blast

But the system doesn’t cool at all. I haven’t hooked up gages to check the pressures.

Could the system be low on refrigerant or is the mono-valve stuck open?

Suggestions please!!

Gauges and a infra red thermomenter are great!

You can clamp the water line to the heatercore if you suspect a failed mono-valve.
Poor performance is most likely just a need for new diaphram actuators in the dash.

Michael

Checked high and low side pressures - they are the same- 80 psi.

Per the manual, if the high and low side pressures are the same, the compressor is kaput.

Or is is wishful thinking that the clutch is slipping and replacing it could bring the compressor back to life.

Thanks.