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Discussion Starter · #1 ·
I am electrically challenged......:). Can you test the fan by connecting directly to the battery, or does the fan resistor prevent that?

I believe my fan has two speeds, does that preclude the presence of a second fan for the AC?

1998 Saab 9000 turbo

Thanks.

Bruce
North Carolina
 

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easiest way to test is by using a jumper ( paperclip works great) at the relays. test the low speed first then the high speed. the ac high pressure switch is one of the ground triggers for the high speed relay the other comes from the ecu
 

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Unplug the harness connector and supply 12VDC to the fan leads. This eliminates the entire contol circuitry and tests only fan function.

Easier to use an old-fashioned battery charger - if you have one. Most newer chargers won't work, they will not power up a totally dead battery or allow use as a power supply.

Whichever way you provide power, attach the negative to the black fan lead. Then connect the hot wire; green is low speed and white is second stage.

IIRC the 1st stage pulls about 4 amps and the high speed about 10 -12.

Almost a sure bet that you have an A/C dedicated auxiliary fan. Look through the slats of the grill. It is mounted in front of the condenser/intercooler/radiator stack - off center to the RH side.

The extra fan is wired to the same relay as the compressor clutch and should start whenever the clutch is pulled in. Quite often it does not spin due to rust around the inner circumference of it's shroud. The blistered paint and rust impact the fan blade tips basically seizing it up. Chip the rust and paint away and many times it will work fine.

When everything is working right, the high speed step on the main fan is more of a failsafe than a control. I hardly ever see high speed kick in on the main unless the A/C dedicated fan is non-functional.
 

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Discussion Starter · #5 ·
You guys should teach a class! Very helpful. And yes, you're right, I havean AC cooloing fan hidden behind the grill. I"ll see if the blades can spin freely.

One more question and I'll be quiet for a while -- if the radiator fan resistor is bad, will the fan still spin if I jump the fan with the battery? (I TOLD you I was electrically challenged......:)

Thanks all.

Bruce
 

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Here's the schematic for a 2 stage main fan motor:



Both leads become common after the resistor. The resistance servres to drop the voltage of on the low speed leg. The high speed side gets a full 12.

If power is applied to the green before the resistor and it doesn't spin the fan, cut the wire and test with the resistor bypassed. If the fan spins, the resistor is bad. If you still get nothing with the direct feed the fan is the issue.


If the fan is the problem, it will be deteriorated insulation on the leads. Renew the wire and protective conduit.






or the brushes/commutator:



the commutator bars will need to be de-glazed and the micas undercut. The brushes will be only stubs.

It can be repaired - if you've got too much time on your hands - but a good used one at the JY is usually $50-75.





In case anyone is interested, below is a matrix listing the cut-in/cut-out temps for vehicle equipped with 2 stage cooling:



SPEED I:

On Temperature 100°C (212°F)Off Temperature 96°C (205°F)


SPEED II:

On Temperature 111°C (232°F)Off Temperature 107°C (225°F)
 

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Discussion Starter · #7 ·
Fan progress

Ok, making progress. Took off grill and confirmed there is an AC fan and it does run when the AC is turned on.

Took out radiator fan and shroud. Wires melted on the end of the resistor.

Now, being emboldened, I wonder if I could replace it with the following:


NTE 50WMD20-PK Manufacturer: NTE Electronics 50W, 0.2 OHM, 1%
NTE Resistors Selection Page
Selection ChartOnline Price: $6.90


Advice appreciated. Thanks! Bruce
 

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Discussion Starter · #8 ·
Fan progress -- 2

Forgot to mention that I jumped the fan directly to the battery and it seemed to run just fine.

Bruce
 

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If the leads are broken your resistor is probably okay.

Is there any wire still showing outside the resistor shell? Don't need much, a half inch is plenty.

If so, get some 105C (high temp) wire of the correct gauge and solder on new pigtails. Make them long enough to reach the point where the harness wiring is still intact. At that point, either butt splice or solder the pigtails into the harness leads.

Use heat shrink tubing for insulation at the soldered connections.

Note (and also reminder to myself):

DON'T FORGET TO SLIDE THE HEAT SHRINK TUBING OVER THE WIRE BEFORE MAKING THE JOINT!!

Nothing sucks like finishing a nice soldered repair and then realizing you forgot to put the HST on. You have to cut the wire and do it all over.

And yes, the NTE 50WMD20 shown above is the correct replacement (.2 ohms/50 watt dissaption rate). The mounting ears also look like a perfect fit to the aluminum bracket.

Learn how to solder and pretty soon you won't be able to play the "electrically challanged" card.
 

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Discussion Starter · #10 ·
Wires were melted together at the resistor. Since all the components connected to the resistor have seen better days, I bought a resistor repair kit on eBay -- includes new resistor, new heatsink, new leads with new connectors/plugs, etc.

My soldering should be limited to the two leads connecting the fan to the resistor assembly. Cost $58 - we will see how it works out.
 
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