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Well, my 95 900 SET with ACC all of a sudden broke. The cabin fan went to high speed and nothing I could do (short of pulling the fuse) would help.
So, I immediately went to Saabnet to find the answer. Thanks to many previous failure-owners, I found that I'd at minimum have to purchase the fan speed controller ($250 Cdn) and if I'm sensible, a new fan (I believe $650 Cdn) because the old fan was likely drawing excessive current.
Call me impecunious, but I wasn't about to blindly spend that (plus labour) without some investigation.
1. I pulled the fan speed controller. Not too bad. About 8 screws to reveal. 2 screws to remove and unplug the harness. Hmm, it looks like it comes apart. WOWEE - the epoxy pixies in Trollhatten didn't conceal this circuit board. UberWOWEE, the circuit looks undamaged except for 1 large transistor/power regulator thingee that is black (matching the discolouration on the circuit board). Hmm, maybe all I need to do is to replace that thing.
2. A quick look at the 3 connector transistor thingee reveals some numbers. IRFP054. Well, a quick trip to Active Electronics Supply for some insulting ("We don't carry those, I don't know what it is, you interrupted my video game! (seriously), go away) leading to a fruitful trip to Sayal (Matheson Blvd) who helped me identify it and offer to order it. I thought, hmm - I think I'll check next door. They helped me cross reference it to an NTE part, the 2920 and sold me one for $23 Cdn. Add in $2.99 for some themal compound stuff and I'm on my way.
Suffice to say, I desoldered the old part and soldered in the new part (taking GREAT pains to protect this MOSFET part from static electricity). Set this all aside for the other half of the story.
3. Check and remove the cabin fan.
Remove the wipers
Remove the plastic facia panel
Remove the wiper mechanism (good opportunity to lubricate, etc.)
Remove the pollen filter
Remove the pollen filter frame (fighting with rusted screws that the R.I.TH. fastened with plain steel screws in this functionally external application).
Unclip the plastic cover over the fan.
Remove 2 screws to lift fan out
Gasp in amazement at the bastardly stupid connector that connects the cabin fan. Who was the idiot engineer in Trollhatten that designed that one??? I ended up cutting it off and soldering in a weatherproof connector (2 conductor flat trailer light connector - $3.99 at CTC) that I also smeared with dielectric grease (protects from oxidation while not impeding electron flow).
I dropped the fan off to a motor rebuilder. For $35 Cdn he cleaned and lubricated it. He also sandblasted the connector. (I thanked him while planning on cutting the bastardly stupid thing off)
So, this morning was re-assembly time. I did the motor first but left it uncovered for test time.
Then I installed the fan speed controller (noting happily that the radio station information was now back on the SID (strange pairing of information in 1 small harness)
Then - the test. I turned the key on and heard - silence. D'oh - I'd forgotten to re-install the fuse. Insert fuse, turn key and the fan came on full blast. Oh oh, is this it? I gingerly pressed the fan down button and triumphantly heard the fan slow down. I turned it back up and went up front to look. Boy does that thing spin FAST. Don't get your fingers jammed in there.
Reassemble (reverse of disassembly) and join me in hoping that this is a long term fix.
Miscellaneous bits:
1. Thermal compound - I used it between the transistor and the large heat sink but I also used it between the small spacer plate and then between it and the mounting point. I figure we should help conduct heat as much as possible. I figured there was no down side.
2. Soldering. I used the small butane torch that CTC sometimes has for around $10. It's a glorified lighter that will stay on and has a nice forceful flame.
3. I believe that the root cause of the fan speed controller failing is the increased current draw due to:
- Dry bearings in the fan
- rusted (yes rusted steel) contacts in the fan connector)
- potentially brushes (though mine were fine)
4. Shopping list:
- NTE2920 (MOSFET N channel Enhancement Mode High Speed Switch) TO247 case
- Thermal compound
- Replacement 2 conductor connector (M and F sides).
- Dielectric grease
- Excellent quality spray grease to lubricate various things while you're in there
- Replacement pollen filter (or clean yours like Dean instructs)
I hope this helps somebody else avoid spending huge amounts of money on over priced, badly designed parts from R.I.TH.
Cheers,
Paul N.
* R.I.TH. stands for Retards In TrollHatten
posted by 216.75.189...
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