HELP please. The heater stepper motor is making me crazy!
Discussion
I rebuilt my Tuscan and in the course of rebuilding it, I had the heater ECU looked at because the temperature and blower control did not work. They came back from repair and apparently worked so I fitted them. A few months later the heater temperature stopped working so I bought a new one from TVR power. They said the motor mechanism was a new design/supplier and needed the arm on the stepper motor gearbox to be made shorter. TVR Power said to replace the steel connection arm between the stepper motor and the hot/cold flap with an aluminium arm which was shorter. The motor worked fine, but I did notice a horrible noise (buurrrrrrmmmm) at every ignition cycle.
A year later and the same thing again, no heat control. I removed the stepper motor again (which is a complete pain in the back) and the gearbox appeared to be slipping. It would push the flap upwards to a point and then drop. So that looked like the stepper motor's gearbox had failed. Back to TVR power and the diagnosis was "over rotation".
I had to buy a new one and had before fitting it properly I connected the wiring and took a look at the behaviour of the arm. The issue I found was that the stepper motor ECU moves the arm anticlockwise 90 degrees every ignition cycle, regardless of its previous/starting position. Therefore, if the flap was at the fully cold position, the motor would try and rotate 90 degrees anticlockwise. This obviously puts huge strain on the mechanism, and with the new motor/gearbox assembly (stepper motor), the b
d is so strong it is stretching and bending the aluminium arm. I think the horrible noise I experienced before was the motor rotating but being unable to go beyond a certain point.
Video to make it clearer: https://youtu.be/RO6iuAUaCPs
My car is a Jan 2000 Tuscan Mk1, and we all know they changed stuff as they went through production. Does anyone have a cut off switch to tell the stepper motor that the flap is fully down and in the fully cold position? From what I can work out, the ECU seems to trying to find a zero position.
I've read on PH about the cluster settings for the fine tuning of the flap position, but my cluster is an early one and I have no control over the flapper preset position. I have access to no settings at all besides the buzzer tone, brightness and some other variable. I've been trying to contact Paul Smith who did the original ECU repair but have had no luck yet. Can anyone else shed some light on why I'm having problems. Its seems that the stepper motor failing isn't uncommon. It sounds like a software issue to me. I've tried to make a cut off switch but that didn't work out.
Any thoughts, experience or advice is more than welcome. I'd love to drive my car this year!, but all the while the heater matrix is loose in the engine bay, I can't drive the car , which is really upsetting considering the weather we've had recently.
Cheers,
Martin
A year later and the same thing again, no heat control. I removed the stepper motor again (which is a complete pain in the back) and the gearbox appeared to be slipping. It would push the flap upwards to a point and then drop. So that looked like the stepper motor's gearbox had failed. Back to TVR power and the diagnosis was "over rotation".
I had to buy a new one and had before fitting it properly I connected the wiring and took a look at the behaviour of the arm. The issue I found was that the stepper motor ECU moves the arm anticlockwise 90 degrees every ignition cycle, regardless of its previous/starting position. Therefore, if the flap was at the fully cold position, the motor would try and rotate 90 degrees anticlockwise. This obviously puts huge strain on the mechanism, and with the new motor/gearbox assembly (stepper motor), the b
d is so strong it is stretching and bending the aluminium arm. I think the horrible noise I experienced before was the motor rotating but being unable to go beyond a certain point.Video to make it clearer: https://youtu.be/RO6iuAUaCPs
My car is a Jan 2000 Tuscan Mk1, and we all know they changed stuff as they went through production. Does anyone have a cut off switch to tell the stepper motor that the flap is fully down and in the fully cold position? From what I can work out, the ECU seems to trying to find a zero position.
I've read on PH about the cluster settings for the fine tuning of the flap position, but my cluster is an early one and I have no control over the flapper preset position. I have access to no settings at all besides the buzzer tone, brightness and some other variable. I've been trying to contact Paul Smith who did the original ECU repair but have had no luck yet. Can anyone else shed some light on why I'm having problems. Its seems that the stepper motor failing isn't uncommon. It sounds like a software issue to me. I've tried to make a cut off switch but that didn't work out.
Any thoughts, experience or advice is more than welcome. I'd love to drive my car this year!, but all the while the heater matrix is loose in the engine bay, I can't drive the car , which is really upsetting considering the weather we've had recently.
Cheers,
Martin
Forums | General TVR Stuff & Gossip | Top of Page | What's New | My Stuff