Rear Blower Prolem

[kevin]

Can anyone shed some light on my rear blower problem.

It only runs in high speed, not slow speed now. I've checked all the usual suspects, relays, resistor, CCu, servos etc, but cannot find the answer either with web searches, or as of yet my trusted Rennlist,

Any direction will be greatly recieved.

kevin.

 

[Dave Wilkinson]

Kevin,

If the blower runs at high speed when it should be running at slow speed the problem has got to be related to the voltage drop imposed by the ballast resistor. Either the resistor is shorted (eliminating the voltage drop) or the wiring is short circuit, bypassing the ballast resistor.

If the blower doesn't run at all when slow speed should be selected there is a chance that the ballast resistor could be open circuit causing no voltage to the blower when in circuit. There could be a wiring problem rather than the ballast resistor but it's got to be less likely.

Any other possibility, like the CCU requesting high speed instead of low speed has got to be so unlikely as near impossible.

I guess it's got to be a recheck over the ground you've already covered - I can't see it being anything else.

Regards


Dave

 

[kevin]

Cheers DAve,

Found the problem, it turned out to be the resistor.....funnily enough it measured ok when in bits, but I guess with the motor drawing large amounts of current the small resistance I measured was enough to stop it working properly.
I also found that the bi-metal spring was not allowing the contacts to return properly, so when it started to work for a second or two it soon stopped as the bi-metal spring wouldn't allow the contacts to return......

New one on order after the weekend......
thanks

Kevin

 

[Dave Wilkinson]

Kevin,

I believe Porsche changed the design of the ballast resistor and I think that bi-metal strip was the main focus of the change. The new one you get will be the new design so hopefully the problem won't re-occur. I have a feeling mine needs changing too. When I got the car the ballast resistor was hanging about in the engine bay, potentially shorting out to anything it came in contact with!! I put it back into it's little slot in the plumbing but I have it in mind to get the later type at some stage.

Glad you sussed it anyway.

Regards


Dave