testarossa blower motor

By "stuck" -- do you mean:

1. full speed works OK, but the fan is dead when the speed control knob is set at any slower speed, or

2. the fan always runs full speed regardless of where the control knob is set?

If #1, the suspects are:

A. power transistor bad
B. micro fuse on speed control unit blown (but not all TR have this fuse -- there are three versions of the speed control unit)
C. speed control unit bad

If #2, this would be rather unusual, but the "full speed" relay could be stuck in the "closed" condition -- either a bad relay or a bad speed control unit always (wrongly) "telling" the relay to be closed.

Please advise which symptom.

 

I can confirm most likely cause is the power transistor. Replacements can be found at any electronics store for a few dollars, but the thing is buried inside the A/C ducting in the dash just right of center (at least on my '86 that's where it was). Sort of like they built the car around this piece. If you have a factory parts book it shows it on one of the last pages.
Ron

 

You can change the transistor, just leave the old failed one in position and tie the new one up under the unit somewhere.. no need to attempt to put it inside the heater unit..

part of the problem is that the transistor is mounted onto a heat sink... and that's fine if you use A/C all the time... but if you run the heater it gets the transistor hot!

Buy a genuine transistor including the heatsink and connector etc.,.. and just plug it in and tie it up under the dash... hanging with the hot parts not touching anything of course...

You need to access the forward part of the centre console... it's only a few screws... the whole job should take no more than 30 minutes.

 

Mine worked on 'high only,' until I changed out the Bosch fuse (silver sq thing) in the fusebox. Works fine now.