I want to install an auxillary heater fan in the engine compartment. It would only be used when its "real" cold Since there is a relay back there, I'm thinking it would be great to use the defroster circuit.

The question is: Did 1975 914's that did not have the rear window defroster installed still have the wiring installed up to the dash area.

If so, then, i will install the window switch. Any suggestions will be greatly appreciated.

Searched for defroster switch info; no much out there. Do you have working rear window defroster ?

What are the wire colors at the switch ?

The wire harness for the rear window defogger was an add-on. It was not part of the harness installed by the factory. I got one off E-bay a while back, but it should not be hard to make one.

First off I would like to say that in my 31 years of 914 ownership living in Minnesota, there is no need for a rear defroster, I have one in my car and I have never had to use it. For sake of installing it I believe the color code on the wire was green or green and white, and brown.

What type of heater were you planning on using?

I am installing an in-line duct fan into the hose that crosses the engine compartment and feeds the passenger side.

Some have recommended using a bilge-blower type ( earlier posts), and my mechanic recommended installing a Detmar brake-duct fan ( which I recently picked up on ebay)

The plan was to wire the in-line fan to the rear defrost relay; install a switch in the dash where the defrost switch would go.

A pelican-parts article shows an install in the front of the car under the cowling; this could be a plan B. I should be able to test which location works best.

What does the wiring harness look like ? Help will be appreciated, I know a lot of 914'rs have defrosters and know the ins-and-outs of the system