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914World.com _ 914World Garage _ Heater Fan Switch
Posted by: UKed Nov 27 2016, 09:36 AM
Hi
An easy question for you.
I'm trying to get the heater fan to work on my 1973 914 2.0lt. The fan motor runs when I wire it direct to the battery. I have a wiring diagram that shows a switch but where is the switch on the car? 
Thanks - UKed
Posted by: bandjoey Nov 27 2016, 09:41 AM
Small red pull up lever just south of the shifter. There's a small square black cover next to it that says Defrost on off. Pull up it starts the fan 
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Posted by: steuspeed Nov 27 2016, 02:19 PM
There should be a green wire attached to the lever. When you pull the lever it completes the circuit to ground.
Posted by: UKed Nov 27 2016, 03:19 PM
Brilliant thanks Steuspeed. i will remove the central console and have a look.
Posted by: UKed Nov 27 2016, 03:20 PM
and thanks to Bandjoey
Posted by: BeatNavy Nov 27 2016, 04:04 PM
Just more info: the green wire in the tunnel under the shifter may be hiding in there. Fish it out with a dental pick or something. It should connect to the tab on the heater lever in bandjoey's picture. When the lever is pulled up far enough ("max" heat) that green wire will ground the relay that's farthest back on the relay board (IIRC) via pin 11 on the 14 pin connector. That relay then provides power to the fan. So, if it's not working check: the green wire is connected, the lever is far enough up, the 14 pin-connector is connected, the relay is getting power, and the relay itself is serviceable.
At least that's my understanding of how it works.
Posted by: Tbrown4x4 Nov 28 2016, 05:58 AM
I just went through this. The URO fan relay had a broken post inside. New relay took care of it.
And yes, it is the rear-most relay.
Posted by: porschetub Nov 29 2016, 01:25 AM
Just more info: the green wire in the tunnel under the shifter may be hiding in there. Fish it out with a dental pick or something. It should connect to the tab on the heater lever in bandjoey's picture. When the lever is pulled up far enough ("max" heat) that green wire will ground the relay that's farthest back on the relay board (IIRC) via pin 11 on the 14 pin connector. That relay then provides power to the fan. So, if it's not working check: the green wire is connected, the lever is far enough up, the 14 pin-connector is connected, the relay is getting power, and the relay itself is serviceable.
At least that's my understanding of how it works.
Rob mine is redundant now as I have headers on my six ,but the wire I had connected was black when I got the car from the PO.
I would like to use it to as a switch for a small electric defroster I will install,did the wire colour change for different years or did I just find the wrong one on there ?
Posted by: BeatNavy Nov 29 2016, 04:12 AM
Just more info: the green wire in the tunnel under the shifter may be hiding in there. Fish it out with a dental pick or something. It should connect to the tab on the heater lever in bandjoey's picture. When the lever is pulled up far enough ("max" heat) that green wire will ground the relay that's farthest back on the relay board (IIRC) via pin 11 on the 14 pin connector. That relay then provides power to the fan. So, if it's not working check: the green wire is connected, the lever is far enough up, the 14 pin-connector is connected, the relay is getting power, and the relay itself is serviceable.
At least that's my understanding of how it works.
Rob mine is redundant now as I have headers on my six ,but the wire I had connected was black when I got the car from the PO.
I would like to use it to as a switch for a small electric defroster I will install,did the wire colour change for different years or did I just find the wrong one on there ?
Hey Porschetub! Pretty sure that wire is green/white on all years, but I could be wrong. Checking back on the wiring diagrams, I see it actually goes to pin 9 on the 14 pin connector (not 11 like I said in post above). Check the continuity between those two to be sure.
Posted by: Dave_Darling Nov 29 2016, 11:39 PM
I just went through this. The URO fan relay had a broken post inside.
A URO part was bad? Color me shocked! </sarcasm>
--DD
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