Heater blower goosed?

[caduceus]

My heater blower has not worked since I've owned the car. So now it's in a state of undress, I thought I'd try and source the problem. Although after doing a search I only found one thread of this problem and taking the blower out sounds about as enjoyable as setting fire to ones pubes.

I remember that I've checked the fuse, but that's it. I've checked the button/switch with a 'combi check' tester thingy bob, and the two left terminals make it beep And with my leccy knowledge (which you could document on the head of a fleas penis) I can deduce that the switch works. I think
So check the plug that's in the dash that feeds it and see if power is going there. If it is, the fan is fubar. Right?

Thanks in advance for any help
Cad

[PhilH42]

I'd look at the heater ECU under the dash maybe.

[rovermorris999]

Can you put 12v directly to the motor to test it?

[caduceus]

rovermorris999 said:

Can you put 12v directly to the motor to test it?

Hi Nick. No. Not unless I remove it, and by all accounts that is not a nice job And my sense of adventure and humour is running out on this project :|

[Discopotatoes]

caduceus said:

rovermorris999 said:

Can you put 12v directly to the motor to test it?

Hi Nick. No. Not unless I remove it, and by all accounts that is not a nice job And my sense of adventure and humour is running out on this project :

Once you have the heater matrix out of the way you will see the panel which has the blower fan behind it, admittedly I never went that far when I replaced my matrix so I don't know if the lower dash has to come out.
I would check the multi pin plugs in that location for corrosion first though

[rovermorris999]

I'd break and make every electrical connection in the circuit and give them a spray with contact cleaner first before doing anything else.

[blaze_away]

Locate the wires behind leftside carpet in passenger footwell, its a connection with a yellow wire and a ? wire (cant remember the colour)
Disconnect them so that you only have those two wires going into the wong area. Put 12v supply directly across them and if you here the fan run the the problem is upstream of that ie wiring to that point of the control module or the switch.

Put a 15 amp fuse in the +ve supply.

[Steve_D]

blaze_away said:

Locate the wires behind leftside carpet in passenger footwell, its a connection with a yellow wire and a ? wire (cant remember the colour)
Disconnect them so that you only have those two wires going into the wong area. Put 12v supply directly across them and if you here the fan run the the problem is upstream of that ie wiring to that point of the control module or the switch.

Put a 15 amp fuse in the +ve supply.

Not clear from the OP if the fan has a controller (with ribbon cable from switch) or if the fan is switched directly at the dash.
Anyway, as above find the cable behind the carpet on the outside face of the passenger footwell.
Cable has 4 wires...
Brown = -12v
yellow = fast
Slate/grey = medium
Blue = slow
If the car has a controller then only the Brown and Yellow will be connected to the car loom.
Unplug and put power to that cable to see if the fan itself is working.

Steve

[mach2]

Chances are it's the connection to the heater control module under the dash top. Well known problem and one that i suffered myself. The power supplied is too great for the wire to handle and it burns out. Can be solved by connecting directly to the board inside the module. There is a thread on here somewhere with good pictures.
I'd be checking this first rather than taking the motor out / to bits....

[QBee]

What age is your car? Do you have the three speed fan controller in black, or the satin aluminium variable speed thingy?

Possible areas of problem:

The connector to the heater control box under the dash (later cars)
The Heater control box itself (later cars)
The wiring connector behind the footwell carpet.
The fan.

I have had all of these except the fan itself.

The advice to put 12 volts to the wires behind the carpet on the left hand wall of the passenger footwell is the best starting point - it will tell you if your fan is working or not.

[Steve_D]

Just had another thought.
If this is the later controller and the heater has not worked since the car was bought then I wonder if perhaps someone has put the ribbon cable on the wrong way round.
Most connectors can only be inserted one way round but the ribbon connector can go either way.
Both the controller and switch have pin one marked as do the connectors on the ribbon you just need good eyesight to see them.

Steve

[QBee]

Looking at your profile pic, it IS the later car - most likely fault is the heater control box plug.
It is under the dash, at the back, straight behind the control on the dash.
Black box the size of 2 x 20 packs of fags stuck together.

[caduceus]

Sorry for the tardy reply chaps. Thanks very much for your replies. Steve, that is handy knowing the wire colours. Will be trying this all out this morning. If it gets working I owe you all a beer at the next TVR meet
Yes, it IS the later type Chim that has the ribbon cable and ally switches.

Fingers crossed.

[caduceus]

Well I think I've found the plug a few have mentioned, behind the carpet in the passenger foot well. But the colours don't match up. Only a yellow and a green are on one end, the other being all the wires. Although I don't see a brown there either



I have tried shoving that red wire (which has a 12amp in line fuse in the holder) in both the yellow and the green, and nothing.I assume it makes no difference whether you unplug it or not? As the temporary + feed gets stuck in to the wire in the plug anyway.

[caduceus]

I unplugged it anyway, still nothing. Are the indicators supposed to work when you test it? (the indicator stalk was on at the time)

[Steve_D]

Your test (wire in back of connector) will not have been providing an earth.

On my '97 I have Green (+12v) and Yellow (earths at the control module) on the car side of the connector.
On the motor side these connect to Yellow and Brown respectively.

To test the motor disconnect the connector and apply +12 to the yellow and -12 to the brown. This connector half being the one with 4 wires.

Steve

[QBee]

Have you tested the control box and it's connector yet? Far more likely to be the problem IMHO

[rovermorris999]

Looks like you're having fun Ged! It looks pretty damp and mouldy in there. Knowing the car's history a bad, or several bad, connections is a good bet.
Now FFS start the bloody engine!

[caduceus]

Thanks Steve. I tested the connections with the current setup and nothing. So then I removed the 12 amp (glass) fuse and tried again and the motor whirred into life! Maybe the fuse is gone, but through the glass there is no apparent break.

So, I have taken the heater control module ends off. There seems to be no immediate burnout residue or major rust. There are no wires inside the module so nothing to check on that side of things.

I'll go back out and plug the plugs back together, connect up the battery, and then check the green for power at the end where it plugs into the box inside the dash.

Does the ECU need to be connected for the fan to work?

[rickprice]

I have a late Chimaera and can attest to all of the above problems surrounding the control box:

I have burnt out both power wires at the connector (yellow and brown from memory, different occasions of course) and have bypassed them (simples, as they say). Instant fix on both occasions.

I have also re-connected the ribbon cable the wrong way around and that doesn't help much.

I would spend time here if I were you; this is one of the extremely rare weak points in the electrical wiring.

Rich