Heater stepper motor problems
Discussion
I am currently servicing the heating and ventilation on the Tamora and have it all in bits. Seeing is beliving 
Incredible design and quality of parts!!!
Anyways having stripped out the covers and flaps etc I have a feeling either the motor or the gearbox is knackered on the stepper motor. Unfortunately availability is zero new or £100 second hand, yep £100! Before I go second hand I want to try and check if the motor and or gearbox are bust.
Any tips on testing? If I split the motor and gearbox both rotate freeley, however if I put power to the motor it starts rotating then after 10/15 seconds it stops. Anyone know how this motor unit should work? What does the accuator actually do - does it simply cut the supply when the flap is fully open?
Any tips guidance or pointers gratefully received, as would be a decent second hand solution if anyone has got one!
Incredible design and quality of parts!!!Anyways having stripped out the covers and flaps etc I have a feeling either the motor or the gearbox is knackered on the stepper motor. Unfortunately availability is zero new or £100 second hand, yep £100! Before I go second hand I want to try and check if the motor and or gearbox are bust.
Any tips on testing? If I split the motor and gearbox both rotate freeley, however if I put power to the motor it starts rotating then after 10/15 seconds it stops. Anyone know how this motor unit should work? What does the accuator actually do - does it simply cut the supply when the flap is fully open?
Any tips guidance or pointers gratefully received, as would be a decent second hand solution if anyone has got one!
roseytvr said:
I am currently servicing the heating and ventilation on the Tamora and have it all in bits. Seeing is beliving Incredible design and quality of parts!!!
Anyways having stripped out the covers and flaps etc I have a feeling either the motor or the gearbox is knackered on the stepper motor. Unfortunately availability is zero new or £100 second hand, yep £100! Before I go second hand I want to try and check if the motor and or gearbox are bust.
Any tips on testing? If I split the motor and gearbox both rotate freeley, however if I put power to the motor it starts rotating then after 10/15 seconds it stops. Anyone know how this motor unit should work? What does the accuator actually do - does it simply cut the supply when the flap is fully open?
Any tips guidance or pointers gratefully received, as would be a decent second hand solution if anyone has got one!
I've done the same on my 92 Griffith so I'm familiar with the motor, gearbox and micro-switches but no idea if its the same on the Tamora. Incredible design and quality of parts!!!Anyways having stripped out the covers and flaps etc I have a feeling either the motor or the gearbox is knackered on the stepper motor. Unfortunately availability is zero new or £100 second hand, yep £100! Before I go second hand I want to try and check if the motor and or gearbox are bust.
Any tips on testing? If I split the motor and gearbox both rotate freeley, however if I put power to the motor it starts rotating then after 10/15 seconds it stops. Anyone know how this motor unit should work? What does the accuator actually do - does it simply cut the supply when the flap is fully open?
Any tips guidance or pointers gratefully received, as would be a decent second hand solution if anyone has got one!
On the Griff the motor turns the flap via some plastic gears within the gearbox, which is integral to the motor. A couple of microswitches cut the motor when it hits the extent of the desired travel (flap fully open or fully closed).
So if the motor is running then stopping it's when the actuator touches the microswitches then thats by design. If the motor continues running but the actuator isn't moving that the gearbox has shed some of their plastic teeth (this is what happened to mine).
Do you have a picture of the motor, gearbox and micro-switches you can post?
Thanks very much for the response. I think it’s different on the Griff but sounds like the same principle. Gearbox and motor separated. Both appear to turn ok by hand.
If I connect the motor without the gearbox should it continue spinning until I disconnect power as the actuator is not connected to tell it that it’s reached the end of its cycle?
If I connect the motor without the gearbox should it continue spinning until I disconnect power as the actuator is not connected to tell it that it’s reached the end of its cycle?
It’s a s
te system on the t-cars. Upon power on, the motor is commanded to go “full cold” for 15 seconds or so. There are no limit switches. It relies on finding its “zero point” by making sure the motor is stalled in the full cold position. From there it then pulses the stepper motor to whatever position you’ve set the temp dial to, right up to full heat, again where the motor is stalled at the other end of the heater flap mechanism travel. Truly ste.
That’s why the gears strip, the motor is forced by the controller to stall to find its zero point.
te system on the t-cars. Upon power on, the motor is commanded to go “full cold” for 15 seconds or so. There are no limit switches. It relies on finding its “zero point” by making sure the motor is stalled in the full cold position. From there it then pulses the stepper motor to whatever position you’ve set the temp dial to, right up to full heat, again where the motor is stalled at the other end of the heater flap mechanism travel. Truly ste.That’s why the gears strip, the motor is forced by the controller to stall to find its zero point.
Thank you - the design is just laughable with possibly the worst heater flap arrangement imaginable!
So can I just check I have this right. At ignition the motor immediately rewinds all the way back to flap zero regardless of setting ie the flap comes down until it hits the buffers.After a short time the motor will then lift the flap until it either hits the setting on the heater controller or the acuator arm depresses the microswitch at fully open. Is this correct?
Reason I need to check this is I have seperated the gearbox and motor and need to reassemble them on there right settings before I start fannying around with the POD settings for flap zero and checking everything works as it should.Obviously assuming the motor/gearbox arent fked!
So can I just check I have this right. At ignition the motor immediately rewinds all the way back to flap zero regardless of setting ie the flap comes down until it hits the buffers.After a short time the motor will then lift the flap until it either hits the setting on the heater controller or the acuator arm depresses the microswitch at fully open. Is this correct?
Reason I need to check this is I have seperated the gearbox and motor and need to reassemble them on there right settings before I start fannying around with the POD settings for flap zero and checking everything works as it should.Obviously assuming the motor/gearbox arent f
ked!Can you possibly connect everything up, leave motor off gearbox, switch whatever is needed for flap to supposedly be fully open, see that motor has rotated to its open position, fit gearbox to motor in a position that ensures the mechanism is now in contact with the microswitch (obviously this is if the microswith is operated @ open), then carry out the settings and check it like this poster did
shep1001 said:
I did mine without the box in place that covers the heater flap so I could see it moving. As has been said every car is different so the only way to know if you have max movement is by trial and error or remove the box that covers it, which in itself whislt technically not difficult is a pain in the arse as it needs to be sealed in again afterwards otherwise it leaks
Shep
here https://www.pistonheads.com/gassing/topic.asp?h=0&...Shep
Just reassemble it all and plug it in. Position doesn’t matter as it’s not actually monitored. The mechanism finds its zero point “automatically“ by way of it forcing the motor to hit the buffers at power on. That’s what the 10-15s of motion in the “cold” direction, irrespective of its starting position is for. It then goes by “dead reckoning” from there until it hits the other extreme of travel.
roseytvr said:
Thanks chaps. Just getting ready to sort it now so I’ll report back later on, Gearbox spins ok when off the motor and motor spins ok for 15 seconds on power up so I’ll connect it all up and see how it goes. I need to make a new frame up for the flap first
That should work ok rosey, it's a crude heath robinson affair, as mentioned above it's searching for a zero reference point, when mine failed the motor coils went open circuit, gearbox was fine but no movement at all and stuck in the cold position, the replacement (second hand) only lasted 2 weeks, the 3rd one is working fine so far, is yours a five or six wire version ?If all else fails, i would be tempted to jam the flap in the 'hot' position and leave the roof off
Well what a faf but we have a result! The motor has 6 cables with another two going to an actuator. As Dave said when you power up the motor automatically turns searching for its flap closed, cold position. On mine there is an acuator that triggers a micro switch when the flap is fully closed which stops the motor turning and shredding gearbox teeth.
The motor will not reopen the flap to your desired setting unless the micro switch has been triggered so its essential that the flap triggers the microswitch at its fully closed position. Some neoprene gaskets later and sealing all joins I have a full blast of cold air via the lower dash vents and hot air via the upper dash and drivers footwell vents. The flap moves freely to all the desired positions. No new motor required thankfully.
Time consuming but very simple when you know how it all works. Absolute shocking quality by TVR but quite clever in its simplicity. Thank you all for your help!
One last question - I have not changed anything on the POD settings for flap zero as I dont need to. The flap is closing and opening as it should do. But was does adjsusting flap zero actually do? The micro switch tells the motor the flap is fully closed and it stops so what effect does changing flap zero have on the settings? Asking out of curiosity really
The motor will not reopen the flap to your desired setting unless the micro switch has been triggered so its essential that the flap triggers the microswitch at its fully closed position. Some neoprene gaskets later and sealing all joins I have a full blast of cold air via the lower dash vents and hot air via the upper dash and drivers footwell vents. The flap moves freely to all the desired positions. No new motor required thankfully.
Time consuming but very simple when you know how it all works. Absolute shocking quality by TVR but quite clever in its simplicity. Thank you all for your help!
One last question - I have not changed anything on the POD settings for flap zero as I dont need to. The flap is closing and opening as it should do. But was does adjsusting flap zero actually do? The micro switch tells the motor the flap is fully closed and it stops so what effect does changing flap zero have on the settings? Asking out of curiosity really
Well the micro switches are a definite upgrade! The mk1 Tuscans have no limit switches at all and rely on the motor being stalled in the full close/open positions, and then it goes from there.
Not sure what the zero point adjustment on the pod does as I don’t have that option on my Tuscan. But as a guess I’d say that it adjusts the virtual zero point once the physical zero point (micro-switch) has been triggered. Say you don’t want the flap to be closed as tightly as the physical zero point gives, backing it off slightly might save wear on the actuator by reducing the force its holding the flap with over extended periods.
Have a play around with it, see what it does and report back. I’m pretty sure they weren’t calibrated as well as they should have been from the factory as that would take time. So it might be worth spending the time to get yours dialed in just right so that the heater flap adjustment system is operating as accurately as possible.
Not sure what the zero point adjustment on the pod does as I don’t have that option on my Tuscan. But as a guess I’d say that it adjusts the virtual zero point once the physical zero point (micro-switch) has been triggered. Say you don’t want the flap to be closed as tightly as the physical zero point gives, backing it off slightly might save wear on the actuator by reducing the force its holding the flap with over extended periods.
Have a play around with it, see what it does and report back. I’m pretty sure they weren’t calibrated as well as they should have been from the factory as that would take time. So it might be worth spending the time to get yours dialed in just right so that the heater flap adjustment system is operating as accurately as possible.
Finally we have a result! Changing point zero does fine tune it but be warned get it wrong and you run the risk of shredding plastic teeth in the gearbox or burning the motor.
On mine, and I suspect they are all different on all cars, you can bend the actuator arm to adjust the micro switch kicking in at closed in the cold position. By increasing the flap zero number it fine tunes the flap and pulls it in tighter to fully closed. However the higher you go with the number the extra strain on the motor as it pulls the flap tighter against the sealing lip. This also means it reduces the flap height at full hot and may not give a good seal on fully hot.
Conversely set the flap zero number to low and the flap doesn’t reach the seal on full cold and goes to far on full hot again straining the motor and gears.
I wouldn’t be fiddling with flap zero in the pod settings without taking the cover off the heater flap and seeing what is happening as there are many variables and there are currently supply problems with new motors.
The main cause of my problems apart from it not being set up right was that someone had tried to fix it, failed, and just completely blocked off the cold vent, therefore hot air only! Furthermore the arm mechanism was fouling on the motor bracket preventing the flap from closing. I would not have been able to sort any of that just by playing with flap zero.
Wish I was on an hourly rate!
On mine, and I suspect they are all different on all cars, you can bend the actuator arm to adjust the micro switch kicking in at closed in the cold position. By increasing the flap zero number it fine tunes the flap and pulls it in tighter to fully closed. However the higher you go with the number the extra strain on the motor as it pulls the flap tighter against the sealing lip. This also means it reduces the flap height at full hot and may not give a good seal on fully hot.
Conversely set the flap zero number to low and the flap doesn’t reach the seal on full cold and goes to far on full hot again straining the motor and gears.
I wouldn’t be fiddling with flap zero in the pod settings without taking the cover off the heater flap and seeing what is happening as there are many variables and there are currently supply problems with new motors.
The main cause of my problems apart from it not being set up right was that someone had tried to fix it, failed, and just completely blocked off the cold vent, therefore hot air only! Furthermore the arm mechanism was fouling on the motor bracket preventing the flap from closing. I would not have been able to sort any of that just by playing with flap zero.
Wish I was on an hourly rate!
roseytvr said:
Finally we have a result! Changing point zero does fine tune it but be warned get it wrong and you run the risk of shredding plastic teeth in the gearbox or burning the motor.
On mine, and I suspect they are all different on all cars, you can bend the actuator arm to adjust the micro switch kicking in at closed in the cold position. By increasing the flap zero number it fine tunes the flap and pulls it in tighter to fully closed. However the higher you go with the number the extra strain on the motor as it pulls the flap tighter against the sealing lip. This also means it reduces the flap height at full hot and may not give a good seal on fully hot.
Conversely set the flap zero number to low and the flap doesn’t reach the seal on full cold and goes to far on full hot again straining the motor and gears.
I wouldn’t be fiddling with flap zero in the pod settings without taking the cover off the heater flap and seeing what is happening as there are many variables and there are currently supply problems with new motors.
The main cause of my problems apart from it not being set up right was that someone had tried to fix it, failed, and just completely blocked off the cold vent, therefore hot air only! Furthermore the arm mechanism was fouling on the motor bracket preventing the flap from closing. I would not have been able to sort any of that just by playing with flap zero.
Wish I was on an hourly rate!
Good work there Rosey! A little knowledge can be dangerous in the wrong hands, also consider all the extra stress for the poor pcbs, leccy components and wiring when over driven into the cold/hot position, the last thing you want before Xmas is a On mine, and I suspect they are all different on all cars, you can bend the actuator arm to adjust the micro switch kicking in at closed in the cold position. By increasing the flap zero number it fine tunes the flap and pulls it in tighter to fully closed. However the higher you go with the number the extra strain on the motor as it pulls the flap tighter against the sealing lip. This also means it reduces the flap height at full hot and may not give a good seal on fully hot.
Conversely set the flap zero number to low and the flap doesn’t reach the seal on full cold and goes to far on full hot again straining the motor and gears.
I wouldn’t be fiddling with flap zero in the pod settings without taking the cover off the heater flap and seeing what is happening as there are many variables and there are currently supply problems with new motors.
The main cause of my problems apart from it not being set up right was that someone had tried to fix it, failed, and just completely blocked off the cold vent, therefore hot air only! Furthermore the arm mechanism was fouling on the motor bracket preventing the flap from closing. I would not have been able to sort any of that just by playing with flap zero.
Wish I was on an hourly rate!
dash harness What 'flap' zero setting did you select for optimal performance ? 18-21 for me, blowing hot and cold nicely
mines ended up on 10 but it is sealing against some neoprene tape at fully open and fully closed. Not sure I qualify as the right hands though, as you will see from this thread I rely on the advice of others.? Long live pistonheads 
Hi roseytvr,
Did you make some pics of this construction inparticular of the parts you mentioned, microswitch, actuator etc.?
I think I will have to go that way as well after a system fault „heater flap“. The result is that I cannot stop the hot air flow regardless of the settings in the dash menue.
However, the motor seems to work as I hear the motor‘s sound when setting its position via the dash menue and it also makes its motor sound with ignition on, which might be its try to find the zero position.
Graham Varley mentioned that the grub screw might become loose. Any idea what grub screw this could be?
Did you make some pics of this construction inparticular of the parts you mentioned, microswitch, actuator etc.?
I think I will have to go that way as well after a system fault „heater flap“. The result is that I cannot stop the hot air flow regardless of the settings in the dash menue.
However, the motor seems to work as I hear the motor‘s sound when setting its position via the dash menue and it also makes its motor sound with ignition on, which might be its try to find the zero position.
Graham Varley mentioned that the grub screw might become loose. Any idea what grub screw this could be?
Granturadriver said:
Hi roseytvr,
Did you make some pics of this construction inparticular of the parts you mentioned, microswitch, actuator etc.?
I think I will have to go that way as well after a system fault „heater flap“. The result is that I cannot stop the hot air flow regardless of the settings in the dash menue.
However, the motor seems to work as I hear the motor‘s sound when setting its position via the dash menue and it also makes its motor sound with ignition on, which might be its try to find the zero position.
Graham Varley mentioned that the grub screw might become loose. Any idea what grub screw this could be?
Granturadriver ...Q. did anyone come good on pictures for this OR did you do the job and take pictures. A@Did you make some pics of this construction inparticular of the parts you mentioned, microswitch, actuator etc.?
I think I will have to go that way as well after a system fault „heater flap“. The result is that I cannot stop the hot air flow regardless of the settings in the dash menue.
However, the motor seems to work as I hear the motor‘s sound when setting its position via the dash menue and it also makes its motor sound with ignition on, which might be its try to find the zero position.
Graham Varley mentioned that the grub screw might become loose. Any idea what grub screw this could be?
Stripped my 2003 Tamora out and posted a pictorial of the strip out on my FB page, found issues with the micros-switch wearing 'teeth' into the lid causing the lid to chatter/bounce, (modified the lid and switch) the stepper motor gearbox failure (ordered, and waiting for it to arrive). I would say (unless anyone can explain it through) that the ECU flap is cycling on every start up and resetting to the strike of the micro-switch, then moving to the last dial setting, with POD 8 setting relating to signal/steps that the ECU gives to the motor before it stops attempting to move (which would relate to the talk of the higher it is set the more pressure it appears to give as it simply repeating itself)...again, I might be totally wrong, as I cannot complete the test until the gearbox is replaced. I do not have aircon, so I am about to remount the fan controller into the empty air conditioning exchanger box (rather than in the dash). A@
Edited by Adrian@ on Monday 6th December 11:01
The OP talked gearbox failure...and I have been chatting the same thing. The gearbox was swappable from a unit purchased THEN from 3.99 (eBay) NOT anything like the same voltage etc. BUT a matched brand (it un clipped) this motor had the same gear teeth number (the eBay seller, actually several did split gearbox off until I found the correct gear. I cannot remember the amount now) BUT that the motor spindle presses out with the gear and can be installed into the old motor IMHO one tooth up or down and POD 8 adjusted, this as a matching set worked for my Tamora A@
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