Heater fan issues
Discussion
I've got a couple of issues with my heater - I think they're independent but I'll explain my theory...
First off - it's a '96 with the 3 speed fan dial, now onto the problems.
1. The blower/fan only works on speed setting 3. I think this could be due to the control module under the dash - so best bet is to take the dash off and take a look? I'm expecting it may need some sort of bypass wire or similar.
2. When switched to position 3, it now blows the fuse (which is annoying as it's the same fuse that drives the gauges). I think this is probably due to a seized fan motor, so probably need to have some fun removing and taking a look at that (passenger footwell area I believe?).
Are my theories sound?
First off - it's a '96 with the 3 speed fan dial, now onto the problems.
1. The blower/fan only works on speed setting 3. I think this could be due to the control module under the dash - so best bet is to take the dash off and take a look? I'm expecting it may need some sort of bypass wire or similar.
2. When switched to position 3, it now blows the fuse (which is annoying as it's the same fuse that drives the gauges). I think this is probably due to a seized fan motor, so probably need to have some fun removing and taking a look at that (passenger footwell area I believe?).
Are my theories sound?
Hi, I have just done this on my 96 Chimaera, if you have 4 wires going to the fan then you have no controller behind the dash (resistor pack on motor).
I removed fan as it had seized (a pig of a job) wd40'd it to free it up and replaced all good now.
for your info when i bench tested mine after unseizing it it was drawing 11.5 amps on speed 3.
just check that the fuse doesnt blow with the motor disconnected and that you have 12v on the loom side connector first, if thats all ok chances are its your blower motor. If you need any more help just shout,
if its two wire then I cant help you, sorry.
I removed fan as it had seized (a pig of a job) wd40'd it to free it up and replaced all good now.
for your info when i bench tested mine after unseizing it it was drawing 11.5 amps on speed 3.
just check that the fuse doesnt blow with the motor disconnected and that you have 12v on the loom side connector first, if thats all ok chances are its your blower motor. If you need any more help just shout,
if its two wire then I cant help you, sorry.
As above if you have this, there is a good chance that the tight motor has burnt the resistor out
https://tvr-parts.com/tvr-parts/part-details/tvr-p...
https://tvr-parts.com/tvr-parts/part-details/tvr-p...
Early cars used all 4 wires from the motor and a switch on the dash to select each resisted circuit.
Later cars use the control module which I think you know has well documented problems with overheated/burnt contacts.
However, I believe it is the same motor with the same 4 wires coming from it and arriving at a connector on the outside face of the passenger footwell but only uses 2 of those wires. Connector is hidden behind the carpet.
Find this connector. I suspect you will find Blue, Grey, Yellow & Brown wires on the fan side and only Yellow and Green on the car side. Disconnect it.
As you already suspect the motor may be drawing a high current make up some test leads with a fuse in line.
On the fan side of the connector apply +12V to the yellow wire and -12V to the brown wire.
If the blower runs and sounds free then its dash off time. If it pops a 15amp fuse its motor out.
Steve
Later cars use the control module which I think you know has well documented problems with overheated/burnt contacts.
However, I believe it is the same motor with the same 4 wires coming from it and arriving at a connector on the outside face of the passenger footwell but only uses 2 of those wires. Connector is hidden behind the carpet.
Find this connector. I suspect you will find Blue, Grey, Yellow & Brown wires on the fan side and only Yellow and Green on the car side. Disconnect it.
As you already suspect the motor may be drawing a high current make up some test leads with a fuse in line.
On the fan side of the connector apply +12V to the yellow wire and -12V to the brown wire.
If the blower runs and sounds free then its dash off time. If it pops a 15amp fuse its motor out.
Steve
Just got round to looking at this.
I’ve got the old style heater control - so 4 wires in and 4 out.
12V is coming out of the connector for each of the speed settings (the medium setting is actually sending 12V through when selected and when set to 0, so I’ll have to have a look at that once I take the dash off at some point) so no issues there I don’t believe.
I set up a test circuit, putting 12V across the yellow and brown wires results in a blown fuse, so it looks like it is a seized motor on the blower that is to blame.
So I assume this means taking it out - from what I’ve read it sounds like an absolute pig of a job with the battery and carpet out...so I’m going to save it for another day as I’m not really in the right frame of mind to tackle it right now
I’ve got the old style heater control - so 4 wires in and 4 out.
12V is coming out of the connector for each of the speed settings (the medium setting is actually sending 12V through when selected and when set to 0, so I’ll have to have a look at that once I take the dash off at some point) so no issues there I don’t believe.
I set up a test circuit, putting 12V across the yellow and brown wires results in a blown fuse, so it looks like it is a seized motor on the blower that is to blame.
So I assume this means taking it out - from what I’ve read it sounds like an absolute pig of a job with the battery and carpet out...so I’m going to save it for another day as I’m not really in the right frame of mind to tackle it right now
Another year on 
and I'm looking at this again!
Just gained enough access to the motor to turn it - was a little stiff and had a couple of leaves in there...I sprayed some WD40 around and it started to free up.
I then applied 12v across the brown and yellow wires again and it fired into life!
Hooray, saves me getting it out...or so I thought!
I then tried the medium and slow fan speeds but got nothing. Only kept it on there for a few seconds at a time with a 30A fuse inline.
So...working on full speed only. I assume I'm going to have to get it out now, is it going to be something to do with the resistors?
and I'm looking at this again!Just gained enough access to the motor to turn it - was a little stiff and had a couple of leaves in there...I sprayed some WD40 around and it started to free up.
I then applied 12v across the brown and yellow wires again and it fired into life!
Hooray, saves me getting it out...or so I thought!
I then tried the medium and slow fan speeds but got nothing. Only kept it on there for a few seconds at a time with a 30A fuse inline.
So...working on full speed only. I assume I'm going to have to get it out now, is it going to be something to do with the resistors?
GR_TVR said:
.......I then applied 12v across the brown and yellow wires again and it fired into life!
Hooray, saves me getting it out...or so I thought!
I then tried the medium and slow fan speeds but got nothing. ...........
Which wires did you test?Hooray, saves me getting it out...or so I thought!
I then tried the medium and slow fan speeds but got nothing. ...........
I'm assuming you are testing at the plug just before the motor.
Yellow is +12V in
Ground Brown for full speed
Ground Slate or Blue for the other speeds.
Steve
Steve_D said:
Which wires did you test?
I'm assuming you are testing at the plug just before the motor.
Yellow is +12V in
Ground Brown for full speed
Ground Slate or Blue for the other speeds.
Steve
Yes I'm testing at the plug.I'm assuming you are testing at the plug just before the motor.
Yellow is +12V in
Ground Brown for full speed
Ground Slate or Blue for the other speeds.
Steve
Ah, I've read in other posts that Brown was the 12v supply and the others the grounds for the speeds (yellow being fast).
Regardless, I have just tested Yellow as the 12v with the other 3 as grounds and then Brown as the 12v with the other 3 as grounds and the only time I get anything from the fan is when the Yellow and Brown wires are utilised.
In short, the Blue and Slate wires do nothing. They don't seem to blow the 30A fuse either, though I didn't keep it on for more than a second.
You might want to check how much current it draws when the fan is running.
I had mine tested recently at the connector under the footwell carpet, and the electrician was holding the wires in his hand while testing.
He commented that they were hot enough to start a fire.
I therefore have had the fan replaced, and my TVR guy spotted that the heater matrix was completely clogged with dust and dirt.
I have never had any worthwhile heat from my heater - always got frostbite this time of year.
Yesterday I drove 160 miles in the car and it was absolutely toasty within 5 minutes of leaving home.
Had to turn the thing down for the first time in 6 years.
I had mine tested recently at the connector under the footwell carpet, and the electrician was holding the wires in his hand while testing.
He commented that they were hot enough to start a fire.
I therefore have had the fan replaced, and my TVR guy spotted that the heater matrix was completely clogged with dust and dirt.
I have never had any worthwhile heat from my heater - always got frostbite this time of year.
Yesterday I drove 160 miles in the car and it was absolutely toasty within 5 minutes of leaving home.
Had to turn the thing down for the first time in 6 years.
GR_TVR said:
Yes I'm testing at the plug.
Ah, I've read in other posts that Brown was the 12v supply and the others the grounds for the speeds (yellow being fast).
Regardless, I have just tested Yellow as the 12v with the other 3 as grounds and then Brown as the 12v with the other 3 as grounds and the only time I get anything from the fan is when the Yellow and Brown wires are utilised.
In short, the Blue and Slate wires do nothing. They don't seem to blow the 30A fuse either, though I didn't keep it on for more than a second.
I had a similar issue on mine, if put current directly to the fastest fan speed it would work but nothing else. It then stopped working altogether.Ah, I've read in other posts that Brown was the 12v supply and the others the grounds for the speeds (yellow being fast).
Regardless, I have just tested Yellow as the 12v with the other 3 as grounds and then Brown as the 12v with the other 3 as grounds and the only time I get anything from the fan is when the Yellow and Brown wires are utilised.
In short, the Blue and Slate wires do nothing. They don't seem to blow the 30A fuse either, though I didn't keep it on for more than a second.
Took the fan motor out (horrible job) and the resistor was fubar and this burnt out the motor.
New motor from tvr parts and plenty of swearing and job done. Had to take the battery, fuse box and lie in the passenger foot well to get it out
Jon Brown said:
I had a similar issue on mine, if put current directly to the fastest fan speed it would work but nothing else. It then stopped working altogether.
Took the fan motor out (horrible job) and the resistor was fubar and this burnt out the motor.
New motor from tvr parts and plenty of swearing and job done. Had to take the battery, fuse box and lie in the passenger foot well to get it out
The resistor can't burn out the motor, the motor can burn out the resisitorTook the fan motor out (horrible job) and the resistor was fubar and this burnt out the motor.
New motor from tvr parts and plenty of swearing and job done. Had to take the battery, fuse box and lie in the passenger foot well to get it out
Jon Brown said:
I had a similar issue on mine, if put current directly to the fastest fan speed it would work but nothing else. It then stopped working altogether.
Took the fan motor out (horrible job) and the resistor was fubar and this burnt out the motor.
New motor from tvr parts and plenty of swearing and job done. Had to take the battery, fuse box and lie in the passenger foot well to get it out
The resistor can't burn out the motor, the motor can burn out the resistorTook the fan motor out (horrible job) and the resistor was fubar and this burnt out the motor.
New motor from tvr parts and plenty of swearing and job done. Had to take the battery, fuse box and lie in the passenger foot well to get it out
I'll be carrying on with this this week...
In the meantime, if I find that my heater now works on the full speed setting reliably, can I add new resistors under the dash instead, rather than taking out the motor?
If so, does anyone know what resistance I would need for the medium and slow speed?
In the meantime, if I find that my heater now works on the full speed setting reliably, can I add new resistors under the dash instead, rather than taking out the motor?
If so, does anyone know what resistance I would need for the medium and slow speed?
I've just testing the current draw on this.
Around 10-10.5A on startup. Then quickly settles to 7.5-7.8A. Does this sound normal?
Plans are to add resistors under the dash to save me getting the motor out.
I'm thinking of say, 5A for middle speed and 2.5A for slow speed...make sense?
So at 12v and 7.5A there's 1.6ohms of resistance, I think.
So if I want 5A I need to add another 0.8ohms of resistance to total 2.4ohms?
And for 2.5A its add 3.2ohms to total 4.8ohms?
I'm just assuming based on no real knowledge other than the equation so please correct me if wrong
Around 10-10.5A on startup. Then quickly settles to 7.5-7.8A. Does this sound normal?
Plans are to add resistors under the dash to save me getting the motor out.
I'm thinking of say, 5A for middle speed and 2.5A for slow speed...make sense?
So at 12v and 7.5A there's 1.6ohms of resistance, I think.
So if I want 5A I need to add another 0.8ohms of resistance to total 2.4ohms?
And for 2.5A its add 3.2ohms to total 4.8ohms?
I'm just assuming based on no real knowledge other than the equation so please correct me if wrong
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.......
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