560SEC Climate Control repairs part 1

When purchased, my 560SEC did not have working climate control. Not only did the A/C not work, but the heater had a mind of its own, occasionally bursting in to life and turning on full heat. Curiously for a car that has been in Australia since the early 2000s, the car had not been converted to R134A.

My first step was to see if the system could work. Overseas readers may not know that in Australia it is illegal to sell freon to the general public. R12 has not been available for many years. Therefore, I booked the car into […]

Finally, a working blower motor

My story of fixing the W126 climate control can be summed up by: If everything points to a problem with an expensive part, don’t waste your time trying to replace the cheaper parts around it in a futile hope it will solve the problem!

After trying a used Climate Control Unit, new fan resistor etc, I finally bit the bullet and bought a rebuilt climate control unit. This solved the problem. In retrospect I probably didn’t need to buy the resistor and I certainly didn’t need the used CCU. It also pays to shop around as a rebuilt CCU was […]

W126 Climate control woes

I’ve been fighting with the W126 Climate Control system for the last few months – and it’s been winning. When I purchased the car in November last year, it was a very hot day and the A/C worked great. It had a new radiator, so I took the evidence of leaking coolant to be history rather than a current problem. Turned out the water pump was leaking and over the next 3 months that leak got worse. My theory is that the leaking coolant shorted out the compressor clutch, as it stopped working around the same time.

I was able […]

Further 300SE A/C Troubleshooting

Previously, I had identified that the cause of my A/C problems was the fuse blowing. I have been narrowing down the problem more and more to the compressor clutch. Therefore, I wanted to eliminate everything else as the compressor is every expensive and beyond my skillset. I had already unplugged two other components that are part of the fuse 5 wiring: The monovalve and the Aux water pump. The other component that is part of this circuit is the aspirator fan. This fan is a very small fan that draws air over the temperature sensor for the climate control. I […]

Troubleshooting W126 Climate Control

When I purchased my 300SE, the A/C worked well. I assume the overall Climate Control system did too. I never did test anything more than max A/C as the weather was very hot. Everything seemed fine, except for the little aspirator fan which was noisy. Unfortunately 3 weeks after purchase, the A/C stopped working. I was sitting at red traffic lights and adjusted the settings and it went warm. This indicated that it was probably not a leak in the system somewhere. Just to be sure, I had the system checked and it was not low on refrigerant.

The first […]