Hi Everyone,

This issue has been discussed here but I was unable to find a thread. Searching skills are not the best.

My 1988 only has the high speed blower, none of the lower speeds. I looked at the schematic and did not see the difference other than the four resistors.
Any ideas what would cause this?

 

Check the resistor pack with a ohmmeter. It should have continuity between all the terminals unpluged. If it shows open, replace it.

 

Common failure. It's the resistor on the air blower (under the rain shield next to the fuse box). They're pricey new... but if you find a used one, it should last a few more years.

 

Here ya go:
http://944time.com/porsche/944-fan-speed-resistor.php

 

Yep, real common. You can prop the contacts of this thermo switch open with toothpicks and soak the whole thing in white vinegar (a mild acetic acid) to clean them. I did this when my fan's low speeds quit and it's been fine for many many years.

 

^ sounds like a great remedy.

 

So, are you familiar with the situation where you hear of something for the first time, and then, suddenly, you see that thing everywhere around you? (Frequency Illusion: The illusion in which a word, a name or other thing that has recently come to one's attention suddenly seems to appear with improbable frequency shortly afterward. Colloquially, this illusion is known as the Baader-Meinhof Phenomenon.)

I caught this thread yesterday. As I drove home, my freaking HVAC unit does the same freaking thing!

Thanks for the info on this. I guess I know what my next wrenching project will be.

 

My fans vary in speed at times and i suspected the resistor pack, ill try the white vinegar cleaning method, i'll drop it in the ultra sonic cleaner with some and clean it up.

 

Update to this condition:

I pulled the resistor pack, yesterday. Super easy. I do wish I hadn't dropped one screw down the blower housing assembly, though!

Everything looked relatively clean and no corrosion visible. I put the unit into a ziploc bag with about an ounce of 5% apple cider vinegar. For some reason, a page I read said that the apple cider vinegar was better to use than the white., No idea.

I let it submerge and percolate for about half an hour. I agitated it periodically, and it got a lot of black particles off. After it had been in for a while, I looked at it, and there was a tsream of black bubbles coming off of each of the switch contacts. I let it go until those streams dissipated in intensity. A quick wash, then a few blasts with canned air/DustOff.

Popped the unit back in, and let it hang in a 95F engine bay for a few hours. Lo and behold, when I got in to drive home from work, I had all of my fan selector speeds, again!

So, can confirm that the vinegar trick worked on my resistor pack. Thanks for the recommendations, all.

 

Good. When I clean these I like to use a toothpick to open up the contactors so the acid can get at the contact tips. I also have had the same issue but found it to be my fan control switch falling apart. It felt normal but was generally broken inside and not working for the lower speeds.

 

Coincidence.....???

http://www.paragon-products.com/product-p/bfrc.htm

 

 

I read the thread title and I think:

No low speed blower
because turbo

 

OMG, Jason, that is freaking hilarious!

Good on ya. Hope you don't mind, but I did save quite a bit more by using my own. Great to know you have a SKU for it, though.

Yup, I guess that's how you make it work.

 

I have to say...I love being around 'car guys'. Smile all the time at what our cars make us do and the occasional humor is just great. Thanks for the way to "save" money on the resistor cleaner.