Evaperator blower resistor

twait01 · 05-29-2007, 07:59 AM

I did an A/C delete but kept the evap blower as a sort of cool air system. Lately the blower only works when I first start the car up. If I drive it and let it sit for a little while it won't work at all in any setting. I originally replaced the switch but the problem is the same. I'm now thinking that maybe the resistor under the passenger footwell is overheating. If the resistor overheats and shorts out would that cut all the power to the evap blower?
Thanks

9dreizig · 05-29-2007, 08:25 AM

What did you do with the relay up front?? If it's still in the circuit, it can get intermittent ( mine did) I suggest replacing or circumventing it.
T

twait01 · 05-29-2007, 08:46 AM

I did order a new one of those. I'll throw that in and see if it helps. Thanks.

Porsche_monkey · 05-29-2007, 11:24 AM

I've had bad resistor connections on other cars, never bad resistors. I silver solder them and the problem goes away. The crimped connections can be flaky. But if your blower does not restart when the resistor cools down, I doubt that is the problem.

twait01 · 05-29-2007, 03:05 PM

Once the car cools down, especially overnight, the evaperator blower works fine. In fact it works until I shut it off. When I try and turn it back on is when I get nothing. Or if I have been driving around and try and turn it on it won't work. I'll check the connections and solder them like you mentioned has worked for you. Hopefully that will correct it. I called the dealer and the parts guy thinks there are two of these resistors left anywhere in the Porsche parts system (new of course). I'm surprised that it cuts all the power. I thought, apparently incorrectly, that the full power switch setting went straight to the relay and the evap motor.

911pcars · 05-29-2007, 03:15 PM

typically, a blower resistor provides different motor speeds by connecting to the switch with different resistor values. At the lowest fan speed, the resistor provides the most resistance, and so on. At full speed, the switch circuit bypasses the resistor.

Can you access both ends of the appropriate resistor? If so, connect a voltmeter and measure the voltage drop during operation and when OFF. The readings should be consistent. If not, you've got a bad connection (e.g. bad, broken, heat-related solder joint).

Sherwood

9dreizig · 05-29-2007, 10:36 PM

I'd bet a weeks wages that it's the relay.. not much of a job to short it out to test...

twait01 · 05-30-2007, 06:23 AM

I'll try and get to replacing the relay tonight. Of course this means I'll have to go out and drive the car to warm it up, man what a chore. I'm hoping you won't lose this weeks pay as the relay is an easy and cheap fix.

twait01 · 06-07-2007, 08:46 PM

Just an update, I replaced the relay about a week ago. Since that time the blower has been working flawlessly.

9dreizig · 06-07-2007, 09:14 PM

Twait01,, glad to hear you got it working in time for that one week of summer you guys get in Minn...!! ( was that this week or is it next week? I get it confused with mosquito mating season week)

twait01 · 06-08-2007, 06:49 PM

No summer hasn't come quite yet, right now were in our monsoon season, then comes tornado season, after that comes our week of summer before the mosquitoes come out and everyone has do head back indoors, which gets you ready for the 10 months of winter.