heater blower fans got mind of thier own!!!

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Datatek said:
You can't just stick a meter across a transistor to test it, there are 3 connections, base, emitter and collector. Depending on type, the Emitter/collector junction should be open circuit with the meter leads one way round and show resistance or open circuit with the leads reversed. Base to Emitter or Collector should show resistance one way and a different resistance or open circuit with the leads reversed.
If the motor was in circuit when you tested, you would be reading the motor resistance.
Click to expand...
I consider myself reprimanded and educated.......:)

I was just going by an instruction on RR.net looking for an easy out...... he just said a dead short between case and terminal means they're duff, I clearly need t o brush up on my electronics
 
AP90 said:
I consider myself reprimanded and educated.......:)

I was just going by an instruction on RR.net looking for an easy out...... he just said a dead short between case and terminal means they're duff, I clearly need t o brush up on my electronics
Click to expand...

My comment was not intended as a reprimand:)
 
Replaced the transistors and as Keith mentioned a bit of a waste of time, I gained a little soldering/desoldering experience, but the r/h fan still ran full tilt.

With a bit of reading, I found that the fans are controlled by output voltage from the HEVAC ECU +12v no speed +6v 1/2 speed 0v full speed, this led me to reckon there was no out put voltage from the ECU

Went on RAVE and found that pins 1 and 3 on connector C245/CO7091 controlled this output. Dug out the ECU and had a fiddle and improved the contact on those pins and now the motors are back in control again.

Worth a shot if you have this problem, been avoiding this fix for ages and it took about 20mins.........especially in this weather!!
 
AP90 said:
Replaced the transistors and as Keith mentioned a bit of a waste of time, I gained a little soldering/desoldering experience, but the r/h fan still ran full tilt.

With a bit of reading, I found that the fans are controlled by output voltage from the HEVAC ECU +12v no speed +6v 1/2 speed 0v full speed, this led me to reckon there was no out put voltage from the ECU

Went on RAVE and found that pins 1 and 3 on connector C245/CO7091 controlled this output. Dug out the ECU and had a fiddle and improved the contact on those pins and now the motors are back in control again.

Worth a shot if you have this problem, been avoiding this fix for ages and it took about 20mins.........especially in this weather!!
Click to expand...
Good one:D
 
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