Would appreciate help in diagnosing if my problem is the transistors or something else.
Firstly do the photos in this guide relate to my 04 xsara with aircon?
I have a 2004 xsara estate with air con
The blower motor does not work.
My wife had the car away for over a month when the fault developed. She tells me the fan just stopped working, but came on sometimes when she went over a bump, then ceased completely.
I have little faith in my wife's recounting of problems, but this is what she told me. She has no knowledge of what appears to be the common 'full speed' resistor problem.
I have read a number of posts about older xsara and zantia fan problems but I am not sure how many of them apply to my car.
I will describe my diagnostics so far and would appreciate if anyone could suggest what further testing I can do:
2 pin plug with heavy red / black wire plugged in. Check for 12v+ and 12v- both Ok (no 12v+ when ignition on but engine not running)
Check for 12v+ at red cable on 4 pin plug going into motor - OK
Connect a test bulb (screwdriver) between earth and yellow wire on 4 pin plugs - a relay clicks, but nothing else happens
When engine running and rotary fan switch turned to approx 3/4 distance, a motor on top of heater unit opens a flap on top of heater unit.
Any suggestions welcome
Link to photos of my cables and voltage checks
Like I said, I don't have a circuit diagram, but assume that the transistors are used as a series regulator, and all this is shorted out when you select full speed for the blower.
Silicon transistors fail by either going completely short-circuit, or the emitter-base junction goes open-circuit, so S/C will give full speed all the time, and O/C will give no blower at all except when you select "full".
Fonz' problem will therefore be nothing to do with the transistors.