Overheated - how to troubleshoot radiator fan? - Saab 9000 Bulletin Board - Saabnet.com
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I just had an overheating incident in my '97 9000 CSE. It happened very quickly while sitting at a stoplight, the temperature gauge started rising and within seconds steam and coolant odor was pouring out of the AC vents! (Fortunately this happened close to home. I nursed the car home adding distilled water, the temperature gauge did not move during the short drive.)
So it looks like either the heater core or hoses suffered a failure, though I'm not sure if that's a cause or a symptom of the overheating problem. A stream of coolant can be seen draining out from underneath the aquarium area.
I've been trying to figure out how to test the radiator fan. So far based on what I've found it looks like the fan is supposed to turn on if the EDU temperature sensor (the one just under the engine thermostat) is disconnected. It does not. I don't know if the fan is supposed to turn on with the AC compressor like on the C900, but it doesn't.
Most of the info I've found says the fan uses an external resistor for low speed operation. My '95 has this resistor, but the '97 does not. Instead the two fan wiring harnesses go right into the fan itself. (Low and high speed windings?) What's the best way to troubleshoot this thing? From what I'm reading the fan itself rarely fails so if there's a problem it's most likely a relay, wiring, or the EDU.
I don't know yet whether the head gasket was damaged. Observation so far finds no coolant in the oil, no oil in the coolant, no obvious pressure being pumped into the cooling system, and the engine runs normally aside from the coolant loss. So possibly it's OK but probably too soon to tell. If there are no symptoms I may retorque the head bolts as a precaution.
UPDATE: I got into the aquarium and what I found is that the plastic tube connecting one of the heater hoses has broken. So the heater core is probably OK. I know the heater core is not original so if it's OK I'll leave it in there.
->Posting last edited on Sun, 3 Jul 2016 11:39:45.
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