[W126 Coupe] Re: AIRCON is "Kaput"

[Dick Spellman]

Dan:

With the engine running at idle and at operating temp set your ACC temp dial
to cool setting and depress the ACC button for AC with blower on High.
Watch the AC compressor for at least ONE minute after switching the ACC unit
on (there can be a delay before it kicks in after depressing the ACC button)
to determine if the clutch is engaged.  If the compressor engages for a few
seconds then cycles off your refrigerant levels/pressures are wrong.  If the
compressor never engages the clutch then see if the compressor has a 3 pin
connector on the compressor body near the clutch.  One of those pins with
12+ VDC applied and engine running should engage the clutch.  If the clutch
cuts-out, your refrigerant levels and pressures are wrong.  If it stays
engaged (test for 60 seconds or so at idle only) then your problem maybe
with the KLIMA relay which should be at the firewall drivers side on an 86.
Try swapping the KLIMA with a known good one.
If while applying the 12+VDC the clutch never engages then you likely have a
bad clutch.

My brief thoughts, may not help.  Taking it to a PRO may provide a faster
and less aggravating diagnosis.

Good luck

Dick