Behr a/c switch mystery???

[DukeRimmer]

I have two a/c sets from 2002. One has three pin switch, the other has four pin. I have 6 sets from e3 cars. Four have three pin, and two have four pin. What's up with this??? Don't know how to test them.

[Guest Anonymous]

Boy can I answer that question! Just went thru this last weekend with a friend's car. All the Behr A/C switches have a locating (polarizing) pin that does not provide electrical contact. The 3 pin switch is for a Bavaria (perhaps others) and the 4 pin switch is for a 2002.

On Behr units, the A/C is wired thru the heater blower, and the A/C switch performs two functions. With the switch in the off position, it allows current to flow between the two wires that run from the A/C switch to the heater blower and the car's wiring harness. With the A/C switch on, it breaks this contact so the heater blower won't work. Frigiking, Mark IV and Clardy units don't do this, only Behr.

For this function to work on a 2002, you need to use a 4 terminal (+ polarizing pin) A/C blower switch.

And BTW, if you want to get rid of one of your 4 terminal switches, I have a friend who needs one (why I learned all this stuff last weekend)

cheers

mike