Climate Control Blues...80' 500SEL

[michael Manning]

well...I pulled the blower motor put 12V to it on the bench, and it's blowing. the climate contol sounds like it's trying to trip a relay ( I hear a clicking) but no fan, no A/C no compressor action...
Can anyone tell me where to go next?

[psfred]

Make sure the vac supply is good -- no vac, no operation.

Also check the blower fuse -- they do go bad and it's not always obvious.

If you have power and vac, most likely the servo has cracked and blown the electronics. This means a new servo ( I would recommend the aluminum bodied one Performance Analysis sells) AND a new amplfier as the old one is now toast.

Not cheap, alas.

Peter

[sixto]

Did you test it on the bench in the same orientation as when it's installed? As the bearings go bad, the brushes loose contact with the armature/rotating part of the motor. Setting the motor on it's side or even moving it may allow temporary contact. Did you test for power at the motor wires?

Blower control is effected by directing voltage through a number of resistors to reduce blower to a certain level. Full voltage goes to the blower for max blower setting, voltage through 4 or 5 resistors goes to the blower for min blower setting. The push-button unit sends a specific signal for max, min and DEF settings, and a modulated signal as determined by the temp control unit for the AUTO setting.

I had an early W126 ACC unit that would only engage the blower motor at max setting, and another early W126 ACC unit that would only start the blower motor at max setting. In the second car, I could swtich to AUTO after a minute of having the blower at max setting. Never figured it out. Maybe things you can check.

Sixto
95 S420
87 300SDL

[michael Manning]

Thanks for the feedback..It all makes sense and I'll check every aspect. To continue...On the fire wall there apears to be two terminal points mounted on a stealbracket. I can feel and hear a clicking. What's going on 'there"? The CC dial is set all the way to cold. That indicates to me me power is making it to that point..right?

The car didn't come with too much info , just an owners manual. Because I believe it's a Euro car I am having trouble finding information about what all the components are. I can't even find a good chart of the 500 SEL Engine compartment for 1980 allowing me to I.D. what everything is. I've bought CD's ,electrical manuals, and still can't find the info I need..have any suggestions where to go for 1980 500SEL detailed information..i.e. pictures detailed charts etc.

Doctormike

[sixto]

It shouldn't look or be much different than an 84-85 US 500SEL.

Sixto
95 S420
87 300SDL