Heater fan not working

[Alan461]

Decided to have a go at fixing it after looking at the thread on the chim forum.
Seems to be quite different to the chims,
On the left there are three connections that correspond to the potentiometers and motors (which work ok),
On the right the ribbon connector to the controls.
And the connectors at the top, there's 12v at the green wire.(slightly melted insulation)
I was expecting the fan motor to be powered by the two larger cores on the left,
Black seems to be earth, black with yellow trace doesn't get 12v when switched on (ign on)
Resistance across them disconnected is massive 1.65 meg
I'd be expecting low ohms from an electric motor.
12v to black/black with trace doesn't do anything.
Can't find the motor, seems to be buried in the matrix housing which means I can't find its connections.
Can anyone offer suggestions? Tia
Alan

Edited by Alan461 on Sunday 5th March 20:17

[Barreti]

There are 2 locations for the heater motor depending on the model of the car.

Pre-cat cars have the heater motor in the void below the NS headlight.
Later 'Cat' cars have the motor attached to the heater matrix unit inside the car behind the glovebox.

[Steve_D]

Alan461 said:

Decided to have a go at fixing it after looking at the thread on the chim forum.
Seems to be quite different to the chims,
On the left there are three connections that correspond to the potentiometers and motors (which work ok),
On the right the ribbon connector to the controls.
And the connectors at the top, there's 12v at the green wire.(slightly melted insulation)
I was expecting the fan motor to be powered by the two larger cores on the left,
Black seems to be earth, black with yellow trace doesn't get 12v when switched on (ign on)
Resistance across them disconnected is massive 1.65 meg
I'd be expecting low ohms from an electric motor.
12v to black/black with trace doesn't do anything.
Can't find the motor, seems to be buried in the matrix housing which means I can't find its connections.
Can anyone offer suggestions? Tia
Alan

Edited by Alan461 on Sunday 5th March 20:17

I don't know the circuit for the Griff but as it uses a control module then it is fair to guess that the logic is similar to the Chim with a module. On that basis I'm going to guess that the blower has power direct to it with the negative side being the fat black/yellow seen in the photo. The module will then earth it and again guessing via the fat black wire alongside.

To test this with ignition on there should be +12 on the black/yellow. If there is then try earthing it.

Also the power for the blower will be on a different fuse to the power for the module. An a Chim these are fuse 14 & 16.

Steve

[Alan461]

Thanks guys, I'll have another try.
The main difficulty has been finding the power supply to the main blower,
it does look like those two black cables but doesn't respond to 12v

[tofts]

OK, just visually there looks to be something not quite right. The large track on pin 5/6 on the heard on the top looks to be lifitng off the board. Excess heat?

Edited by tofts on Monday 6th March 20:07

[Alan461]

Well spotted, the photo is poor for the detail to be clear, seems the solder has run under the track on either one and at the other end next to the heatsink.
Although this looks worrying the continuity is good on each one.
Pin 5 is the slightly melted green wire on the harness.
Thumbsnap reduces the res on the photo, this is best It will do.

[tofts]

Could you post a photo topside? My gut says theres a power mosfet there...

[Alan461]

Yep. With a massive heatsink

[tofts]

OK that makes more sence, I think the lifitng track might be incidental. Although i would like to know what the relay is running.

The two spade terminals are on the "source" and "Drain" of the mosfet, which means one is in one is out. Hence testing across the leads yields nothing.

Knowing how Tina used to wire these, I would suspect that the motor driven is via a PNP mosfet, which means the motor is live and thus one lead will be 12v (my guess would be yellow black). In which case, grounding one of the two wires should make the motor run. The other i would suspect is ether a permanent ground. 5 minutes with a multimeter shoudl determine all, be careful!

EDit:

Reading your post again you get "nothing" on black yellow, suspect fuse and/or fault with motor.

Edited by tofts on Monday 6th March 21:48