As Marshall says the feeds are triggered on pos1 - the hevac then when it comes on drives the transistors to the operate the fans at the desired speed. Unless they're short at least :)
That's handy you can get the controller so readily - I didn't realise that.
When Dave (DHailsworth) pressure tested his AC at the 3 bar that RAVE recommends, there were no leaks, but when he tested it at the AC training course recommended 10 bar, there was. So you may still have a leak, but with dye in you'll soon see it.
I've taken a couple of blowers apart and the commutator was burnt in places so not all poles were working. Vibrates like hell when running flat out and may also not start if it has stopped with the brushes on the dead spot.
Thanks Gents...
If the Transistor is dead then it allows the 12v to run the Pax fan even if the HVAC isn't on?
If hypothetically it wasn't the transistor, could there be another thing that would cause the issue?
H
No, it's the transistor. As soon as power is applied the blower runs flat out.
Ah right I gotcha.
Luckily it shut down when the key was pulled.
It will. When you turn the key to Pos 1, the ignition switched circuits are powered, including the feed to the blowers. Ordinarily, the blower doesn't do anything because the HEVAC hasn't yet instructed the controller to turn on the transistors to supply power to the motor. When they fail and the transistors go short circuit, the power goes straight through them to the motor.
Ahh gotcha!
Thanks Richard!
Well.
New fan obtained and fitted.
old unit had green dust and all kinds of shit falling out of it.
New unit fitted.
All the fans now work, and my HVAC book has disappeared!
Well happy.
Just in time for the weather to turn all miserable and wet again.....
Yep i'm good with timing LOL
Atleast it can demist the windows!
Hi StrangeRover, did you buy a S/H unit, or a new one ?
Pierre3.