A.C. Problem.. - PeachParts Mercedes-Benz Forum

McDiesel · #1 08-23-2004, 12:24 AM

have you checked your strip fuse?

mine is in a seperate little cover... it looks sorta like this like |_|_____|_|

i believe they are 30 amp fuses... mine is located right above my drivers side strut under a black plastic cover with two copper leads going to it..

hope this helps'

pberku · #2 08-23-2004, 02:34 AM

Look at yesterday's (Sunday's) Diesel Forum. You will find a discussion called "A/C & Tach problems" The answer to your question is there.

Below is an extract.

The AC speed sensor, and the engine speed sensor both feed their signals to the KLIMA relay. The output of the two speed sensors is then compared and it if differs by more then approximatlery 10% the KLIMA relay shuts off the AC. The presumption being that the belt is slipping or that the AC compressor is seized.

The engine speed sensor also provides the input for your Tach. In your case it sounds like the engine speed sensor is not functioning properly, thus the Tach stops working and the KLIMA relay shuts off the AC as it sees different speeds at the engine and AC Compressor.

Fix your engine speed sensor and you should be OK.

Phil

McDiesel · #3 08-23-2004, 09:11 AM

thanks to all!!

my car is going in the shop today
to get the spped sensor fixed.. hoppefullly it will fix the ac prob!!

McDiesel · #4 08-24-2004, 09:24 PM

well the car is in the shop and im away on vacation.. but the mech quickly put the that senor that sends the reading to the tach and that was not it.. Still no tACH..

\

he is going to run a full diag on the thing from tranny sending crankshaft sensor OVP Kilma etc entire ac system from all those diff things AFTER he gets the TACH to work.. ugghh.. hope its not the Tach itself .. the instrument cluster is in there pretty loose from me replacing the dash bulbs recently, and i made sure not to snug it in tight like it was from the factory!

should be easy for him to get to the tach wiring..
i swapped relays except for my OVP because my 1990 is a different one from the 1992... really confusing to the Mech too he thought for sure that the speed senor would do it.. I know the kilma in there is ok and all of the fuses etc even the two on the ovp..

wish me luck and Im still open to suggestions!!

McD

FlyDad911 · #5 08-26-2004, 06:34 PM

If the engine speed sensor is not the problem, then the most likely cause is the voltage regulator. The secondary problem may be the output of the alternator itself. Is the ABS light coming on at the same time the tach drops offline? Then it's voltage from one cause or the other.

Hal

'87 300D Turbo (290k)
'83 911SC (106k)

McDiesel · #6 08-26-2004, 08:30 PM

Well thanks to all who replied!

it turned out to be a combination of 3 problems
1. r.p.m. sensor
2. a/c kilma relay
3. over voltage protection relay

i had to put an altenator in 3 weeks ago,,
then in less than 2 weeks had to replace the new voltage regulator in the altenator..
Mechanic told me that the ovp probably was shot when the first altenator fried...
which lead to the second voltage regulator getting fried too..

tokk 2 hours in labor @ 76 bux an hour = $152.00
plus the cost of the parts
$ 46 for rpm sensor
$ 120 for kilma
$70 for the ovp relay

now she works BETTER than Ever!!

cant be without AC here in Humid South jersey!!

thanks again to all!
McD