Loren Faeth wrote:
Looks like there is a compressor control relay, N8. I don't see it in the
component location diagrams. I guess it is similar to the 123 300D Klima
relay. Now if I can find it. Looks like i might have a bad clutch or a
bad relay or something else yet that is an input to the compressor
relay. Looks like there are 4 switches with input to the relay. ACCfrom
86.pdf, number 305 126.125
The HVAC for a 126.125 is VERY complex and last time I counted there are
about a dozen different causes for the compressor clutch to NOT engage.
You need to run the diagnostics outlined in the 126 HVAC manual. After
insuring that the fuse that powers the compressor clutch (F-5 I believe)
is working you start by removing the KLIMA relay (N6 - located between
the two firewalls) and jumping pins 5-7 together and the clutch should
engage and the compressor run. If there is sufficient refrigerant, the
air output should quickly cool.
If the compressor runs but doesn't cool, you need to have any leaks
repaired (could require a new compressor or the manifold hoses - both
are EXPENSIVE) and the system recharged. If the engine stops or the belt
makes a heck of a racket you will probably need a new compressor. If
tachometer is NOT showing engine speed, you will need to find why - it
may be a failed overvoltage protection relay or any connection between
the engine speed pickup (L3) and the tach.
I haven't covered all the possibilities - could be a slipping belt, oil
grease on the clutch or an open, intermittent or shorted clutch winding,
a bad evaporator sensor or compressor speed sensor or it's contacts or a
failed temperature sensor or sensors. The system IS complex and time
consuming to diagnose. It may also be expensive to repair even after
it's diagnosed or repair can be quite inexpensive, but that depends upon
what's wrong!
I have NEVER found a bad KLIMA relay (but they do occasionally fail).
Something else is wrong 90+% of the time from the reports I've seen and
my personal experience.
Marshall
--
Marshall Booth (who doesn't respond to unsigned questions)
"der Dieseling Doktor" [EMAIL PROTECTED]
'87 300TD 182Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi, '84
190D 2.2 229Kmi (retired)
