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Discussion Starter · #1 ·
Hi everyone just a quickie please. I just had my Saab 900 AERO 91 serviced and had the thermostat and fan switch replaced. However my temp gauge that used to sit at about a quarter of the way up from the bottom then rise to just above halfway I hear a click and the fans switch on , now sits at the halfway point and doesnt move even when the car is static and the fans are running. Has the mechanic done something to it or is this normal. The reason I ask is cause Im paranoid about headgaskets:confused: Cheers in advance Bjorn.
 

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If you mean that the car warms up normally, the needle rises to half way and just sits there then this is how it should work - the thermostat is regulating water flow to the rad and if the rad can't cope on it's own the fans come on and deal with the heat.

If you mean that as soon as you start the car from cold the needle hits half way then there is something wrong.
The way your temp needle was acting before was a symptom of a knackered thermostat.
 

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If the engine temperature goes to 50% and stays there then you have nothing to worry about.

philjohnhb said:
The way your temp needle was acting before was a symptom of a knackered thermostat.
I disagree. The behaviour sounds like a fan switch mismatched to the thermostat.

If the thermostat has a low threshold and the fan switch has a high threshold, then the engine temperature will swing between those two values. Low when on the move, higher when stationary.

It's far better for the thermostat and fan switch to be properly matched so that the engine temperature remains stable. Stable engine temperature is better for head gasket longevity.

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Discussion Starter · #4 ·
Genius, thanks guys I will sleep ok tonight. Didnt think that there was a problem with the old set up but now knowing how it should be it seems the mechanic hs done an ok job;) . Thanks for your help as always
 

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Can you get fan switches with different ratings? I could only find one on pfs and it didn't state the rating whilst I have seen thermostats at 82, 89 & 92 degrees?
 
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