Hello,

I would like to know if anyone can supply the following information:

The pins to use to diagnose 1990+ 8 pin diagnostic connector for W126 A/C and the voltage the L.E.D. needs to withstand.

&

The way to test the below referenced switches and relays:

A/C E.T.R. Switch = Evaporator Temperature Regulation Switch.
A/C Evap Temp Sensor
A/C Lock-Out Sensor
A/C Pressure Switch
A/C Temp. Switch
Aux. Fan Resistor
Auxiliary Fan Switch

I know that the E/M clutch for the compressor just passes current like American Cars, but they are pretty much the only ones I've worked on recently. I would assume that the switches would be normally open and Ground on activation or failure, the Resistor is so deep in the secondary firewall that I can't get leads on it (Do any of you know how to change it without removing the Brake Booster. My hands don't fit.) I think that many of the W126 A/C problems are probably easily solved; but for greedy Mechanics.