Heater fan issues
Discussion
Penelope Stopit said:
Unfortunately the job isn't that simple, the resistor pack relies on the air circulating around it in the air-box to cool it, you would have to fit a resistor to a heat-sink and mount a fan motor to cool it. A resistor and cooling device could be fitted up front in the engine bay, but.......
Ah OK, that's a nuisance! Can the resistor pack be replaced (easily) once the motor is out? Or is it a case of biting the bullet and getting a new motor unit.
Yes the resistor can be replaced easily, the problem is that a tight motor is often the cause of resistor failure, due to the work involved you must make sure the motor bearings/bushes are good and well lubricated or fit a new motor at the same time as fitting a new resistor
If you do decide to lubricate the motor bearings you will also need to make sure the brushes have plenty of length(life)
If you do decide to lubricate the motor bearings you will also need to make sure the brushes have plenty of length(life)
Penelope Stopit said:
Yes the resistor can be replaced easily, the problem is that a tight motor is often the cause of resistor failure, due to the work involved you must make sure the motor bearings/bushes are good and well lubricated or fit a new motor at the same time as fitting a new resistor
If you do decide to lubricate the motor bearings you will also need to make sure the brushes have plenty of length(life)
Noted - thanks.If you do decide to lubricate the motor bearings you will also need to make sure the brushes have plenty of length(life)
Next step is get the damn thing out then I suppose!
Is it possible that the reason you only have speed 3 is that it takes that much ooomph to shift a fan motor that has virtually siezed bearings?
I have the mark 2 arrangement, with an alloy on/off switch for the fan than then rotates to alter the speed, rather then having three positions.
My heater fan was drawing serious amounts of current thanks to worn out bearings, so much so that it was burning out my heater control box regularly as well as making the wiring seriously hot.
New fan was fitted for me (pig of a job) and the heater matrix cleaned at the same time, as it was clogged after 108.000 miles and 19 years (actually clogged when I bought the car in 2012). I now have a proper working heater for the first time
I have the mark 2 arrangement, with an alloy on/off switch for the fan than then rotates to alter the speed, rather then having three positions.
My heater fan was drawing serious amounts of current thanks to worn out bearings, so much so that it was burning out my heater control box regularly as well as making the wiring seriously hot.
New fan was fitted for me (pig of a job) and the heater matrix cleaned at the same time, as it was clogged after 108.000 miles and 19 years (actually clogged when I bought the car in 2012). I now have a proper working heater for the first time
A common failure for these motors also used in GM/Saab back in the day was the steel shaft rusts and jams in the bearing/bush at the opposite end to the brushes 
some may force the bearing to rotate in the housing instead (not ideal) or generally seize altogether fuses blowing etc , if you can get the shaft to rotate again within the support bearing with lube your laughing
some may force the bearing to rotate in the housing instead (not ideal) or generally seize altogether fuses blowing etc , if you can get the shaft to rotate again within the support bearing with lube your laughing QBee said:
Is it possible that the reason you only have speed 3 is that it takes that much ooomph to shift a fan motor that has virtually siezed bearings?
I have the mark 2 arrangement, with an alloy on/off switch for the fan than then rotates to alter the speed, rather then having three positions.
My heater fan was drawing serious amounts of current thanks to worn out bearings, so much so that it was burning out my heater control box regularly as well as making the wiring seriously hot.
New fan was fitted for me (pig of a job) and the heater matrix cleaned at the same time, as it was clogged after 108.000 miles and 19 years (actually clogged when I bought the car in 2012). I now have a proper working heater for the first time
Certainly possible, although the amp draw I'm getting doesn't seem too bad now I've lubed it all up. I guess we'll find out I have the mark 2 arrangement, with an alloy on/off switch for the fan than then rotates to alter the speed, rather then having three positions.
My heater fan was drawing serious amounts of current thanks to worn out bearings, so much so that it was burning out my heater control box regularly as well as making the wiring seriously hot.
New fan was fitted for me (pig of a job) and the heater matrix cleaned at the same time, as it was clogged after 108.000 miles and 19 years (actually clogged when I bought the car in 2012). I now have a proper working heater for the first time
So, here's the resistor - the yellow wire has actually broken off, which would explain why speeds 1 and 2 don't work...!
I still need to check if the resistor has "gone bad" or if I can simply solder it up, but if we assume it's bad - how do I source a replacement?
I am investigating my heater. It was pretty stiff but soon free’d up after a dosing of WD40
No control box so just 4 wires going to the motor.
In the car the heater will only work on low speed.
With the motor on the bench:-
If I put +12v on the yellow wire and ground the brown I get the fastest speed. Grounding the grey or blue does nothing apart from making the resistor very hot.
If I ground the brown wire, +12v on blue give slow, +12v on grey gives medium, +12v on yellow gives fast.
Does this mean the resistor is goosed?
No control box so just 4 wires going to the motor.
In the car the heater will only work on low speed.
With the motor on the bench:-
If I put +12v on the yellow wire and ground the brown I get the fastest speed. Grounding the grey or blue does nothing apart from making the resistor very hot.
If I ground the brown wire, +12v on blue give slow, +12v on grey gives medium, +12v on yellow gives fast.
Does this mean the resistor is goosed?
Edited by KugaWestie on Sunday 23 January 12:41
Further investigation shows the dash switch is only putting +12v out on the low speed setting, click the switch to medium or high and none of the 3 cables that end up on the blower are showing +12v
If I put a jumper wire from the switch +12v terminal on the back of the switch and then put the other end of the jumper wire onto the other three connections on the switch I can get the fan to work on all three speeds.
The cold air fan in the driver footwell works on all three speeds and the switch is the same. So I swapped the switch over onto the heater circuit and it makes no difference.
I am confused!
If I put a jumper wire from the switch +12v terminal on the back of the switch and then put the other end of the jumper wire onto the other three connections on the switch I can get the fan to work on all three speeds.
The cold air fan in the driver footwell works on all three speeds and the switch is the same. So I swapped the switch over onto the heater circuit and it makes no difference.
I am confused!
Edited by KugaWestie on Sunday 23 January 12:42
KugaWestie said:
I am investigating my heater. It was pretty stiff but soon free’d up after a dosing of WD40
No control box so just 4 wires going to the motor.
In the car the heater will only work on low speed.
With the motor on the bench:-
If I put +12v on the yellow wire and ground the brown I get the fastest speed. Grounding the grey or blue does nothing apart from making the resistor very hot.
If I ground the brown wire, +12v on blue give slow, +12v on grey gives medium, +12v on yellow gives fast.
Does this mean the resistor is goosed?
No control box so just 4 wires going to the motor.
In the car the heater will only work on low speed.
With the motor on the bench:-
If I put +12v on the yellow wire and ground the brown I get the fastest speed. Grounding the grey or blue does nothing apart from making the resistor very hot.
If I ground the brown wire, +12v on blue give slow, +12v on grey gives medium, +12v on yellow gives fast.
Does this mean the resistor is goosed?
Edited by KugaWestie on Sunday 23 January 12:41
KugaWestie said:
If I put +12v on the yellow wire and ground the brown I get the fastest speed. Grounding the grey or blue does nothing apart from making the resistor very hot
By doing this you were connecting positive to negative through the resistors, close to a short circuit and damaging the resistors if left for any length of timeKugaWestie said:
If I ground the brown wire, +12v on blue give slow, +12v on grey gives medium, +12v on yellow gives fast
Very good, proves the resistor is okKugaWestie said:
If I put a jumper wire from the switch +12v terminal on the back of the switch and then put the other end of the jumper wire onto the other three connections on the switch I can get the fan to work on all three speeds
Very good, proves the wiring from heater box to switch is okKugaWestie said:
The cold air fan in the driver footwell works on all three speeds and the switch is the same. So I swapped the switch over onto the heater circuit and it makes no difference.
I am confused!
Jobs easy from here onI am confused!
The termination at the switch is not good, perhaps burnt terminals. Slim chance of a termination problem as you'd have seen it but...............
Switch is wired incorrectly
Connect only the supply to the switch and check its switching combination with multimeter at the other 3 terminals 1 by 1
Edited by Penelope Stopit on Sunday 23 January 13:12
So satisfying when something you have fixed yourself actually works properly.
Well done.
Not something I experience often, though the debtor reconciliation I did this afternoon worked first time for once.
It normally takes me several weeks of farting around with a calculator and a spreadsheet.
Well done.
Not something I experience often, though the debtor reconciliation I did this afternoon worked first time for once.
It normally takes me several weeks of farting around with a calculator and a spreadsheet.
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