300SE Double relay change

The saga of my non functional A/C is now over.   The 300SE is blowing cold air.   It would want to after all the parts I had to change to get this far.   The final piece of the puzzle was the Klima relay.   This relay controls the engagement of the compressor and had burned out when the clutch shorted.   I ended up buying a rebuilt relay from the same vendor as my rebuilt Climate Control Unit.    The A/C is fixed just in time for the hot Sydney summers.

Coincidently, at the same time I needed to change the Klima relay, I had another relay problem.   Symptoms were very hard starting and poor running when cold, as well as the ABS light on.   This normally points to the Overload Protection Relay.   The Overload Protection Relay protects the sensitive electrics on the car, in this case the engine ECU and the ABS controller.

They are known to go bad after a while and my old one  is date stamped 1996.   This relay is fairly cheap (about $50-60) and protects very expensive components, so if it has not been changed in a while its always worth having a spare on hand.  There are a few different part numbers that vary on year so it is important to get the right relay for the car.    It has a 10W fuse in the top which is worth checking.  Sometimes just this fuse is bad, although most often the whole relay needs replacement.

I now have no more ‘urgent’ repairs on this car.   There are a few smaller items that need attending to that I can do slowly.   For example, the left hand bulb in the instrument cluster is not working.   I need to pull the cluster anyway to fit a gear with one less tooth to make the odometer more accurate.