Heater Wiring

[Howard81]

The heater in my MKIV was completely knackered so I've purchased a complete secondhand unit from the Spitfire Graveyard. I'm a bit stuck with the wiring..

On the heater unit itself there are 3 wires coming out of the base. Green/yellow, green/grey and black. The green/yellow and green/grey wires connect to the control slider plate. The black wire terminates with a female spade connector and is not connected to anything.

On the blower itself there are two terminals. One of them has a short green wire going into a single bullet connector block. The other is empty.

So in wiring it up..

1. Where does the white/pink (ignition feed supply) go?
2. Where does the short green wire from the blower go?
3. Where does the black wire from the base of the heater go?

I have a suspicion that the black wire goes into the blower, and the green wire attaches to the ignition feed.  However the wiring diagrams just confuse the matter!

Thanks in advance :D

[Falkon]

Power to the motor is always hot. The switch is a grounding unit. Here's a '73 RHD.

http://www.spitfiremk2.co.uk/mk4rh73.html

[drofgum]

Howard,
The component list for that diagram is wrong. The heater fan motor is 53. The switch is 55. 54 is a resistor for low speed.
                                                                        Cheers,
                                                                        Paul

[Nick Moore]

I wired up my GT6’s blower this week, using this wiring diagram:
http://www.mygt6.com/site/wp-content/uploads/2011/06/GT6MkIIIwiring.jpg

Mine also had two wires to the blower, a green live supply and a black to connect the motor to the switch. Maybe it shouldn't have been black but I see yours is as well. The component I cam't see in the photos, though, is the resistor to make the blower run slow. On my car it's riveted to the heater box.

The final piece in the puzzle was that the contact slider tracks on the switch were corroded. A tickle with 600-grit paper and some WD40 cured that. Oh, and the system won't work until the switch body is earthing against the car. Held in your hand, it'll do nowt!

[Howard81]

I've sorted it now!

I was right, the black hooked up to the other side of the blower motor and the short green wire goes to ignition.

I've got it all plumbed in but haven't run the car yet as also need to replace the water valve. Are there any tips on getting it running without causing an airlock?