heater blower, constant full-on

[izzywiz]

Hi all, I put in a post recently about my problem with the heater blower on a '94 2.1vsx td auto estate, which was traced to a hot-spot on the fuse in the engine-bay, after changing the blower control unit, last year, thinking that would be that! Of course it isn't and wasn't 'that' as I now have a heater blower which wants to run at full speed and won't even turn off at the control switch.
After putting up with it in the warm weather I have been trying to puzzle this one out but, apart from pulling the fuse (now the weathers' gone cool!) I haven't got really much further.
As the speed control was set at the lower end (1-2) when the fault developed I tend to suspect the control module again but would welcome any other thoughts from anyone.
Regards izzywiz

[Peter.N.]

Hi Izzywiz

Sounds as though the transistors that form the speed regulator on the motor have failed, more specifically gone short circuit. If you are handy with a soldering iron they are not to difficult to replace. You can check this by disconnecting the small plug from the control panel, if it still runs that's what it will be. You could otherwise fit a secondhand blower, one from a ZXantia would do but not a 406, they run the wrong way.

Peter

[izzywiz]

Peter, thanks for this - I'll check it out and come back,
Izzywiz

[techmanagain]

The suggested solution to the probleem is bang on the dot from my experience. There is no identification on the transistors to assist, but this problem hasd neen discussed so often thatt it must be on the XM files somewhere. If it can't be found, I'll search my file and post it in due course.The transistors can be bought from Maplin or similar.

[Peter.N.]

Its at the bottom of my signature