Mercedes Benz W126 560SEL 3/89 Testing & Overhaul of Electrical System and All Control Units Part 3

Part 3 of this Series deal with the Automatic Climate Control Unit. This one here is an all original Mercedes Benz Part with a manufacturing Date of November 1988.

[@cbjodd5878]

Thanks for sharing your expert competence on the mighty 560.
If everyone were like you, there would be peace on earth. (That goes for Clay also.).

[@moestrei]

I found that the 5V rail on these were very noisy. After replacing the 2 brown cylindrical 30uF capacitors (one on each PCB) the controller was functioning again. Same problem on 3 units I had for repairs.

[@Lizpolygigiblissgirl]

Do you recall the value of the orange tantalum capacitor? I stupidly put everything back in the car without writing it down. I repaired all the vacuum actuator pods (3 out of 6 were shot)but it seems that this climate control module is also disfunctional.

[@inovahightechltd]

No, I don’t. I have one unit open and it doesn’t have a tantalum cap.

[@Lizpolygigiblissgirl]

@@inovahightechltd Ok, thank you

[@Lizpolygigiblissgirl]

Is there a secret to getting the circuit board out? I have the unit out and the plastic backing plate off exposing one side of the board but I want it out like you have it so can change these caps out... I dont want to break anything!

[@inovahightechltd]

Quite tricky. Remove the 4 tiny Phillips screws on bottom side of PCB. Carefully remove all plastic buttons. They pull straight out. Pull out both light bulbs with a small plastic tube and remove temperature wheel as described in the other comment.
Then very carefully lift out the main PCB with the other two smaller once more or less at the same time

[@Lizpolygigiblissgirl]

Is it that flathead screw on the temp roller switch?

[@inovahightechltd]

No, it’s a plastic pin. It comes out by just pulling it straight out with a small set of needle nose pliers or larger tweezers

[@Lizpolygigiblissgirl]

Got it! Everything is like a brainteaser puzzle with these cars, I love them. Im only a year into these cars, a 1990 w126 thats a daily driver. Your channel is one of the best, and i love your stories about your time working at the factory during the last of the good years. Thanks for the reply!