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Two fans of Z34


Laveen Z34

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The two fans of the Z34, are they supposed to be both on to cool the engine down or one is for the engine and the other for AC? If you're facing the engine the one on the right is the one that comes on when the engine is hot. The one on the left doesn't run even if I turn the AC on (though I don't have any cold air now since I believe I have to replace my compressor and charge it up with freon). Just needs your masterful opinion of course.

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The right fan is the main fan and comes on to cool your engine. So does the left fan. It will come on at 227*F or so. I'm pretty sure they do not affect your AC.

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Hmmm. Left fan never comes on and at one point my Z34 had a cracked radiator and temperature needle was all the way to last white line (how hot is that, do you know?) before the red and the fan on the right will kick in but never the left. I should pull it out and test it, what do you think? Any other ideas?

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That is about 245-260. Depends because there are no numbers on those gauges. The fan should of kicked on at that point. It doesn't take much to pull it out. Three bolts on the fan.

 

Pull it and test to see if t works. If not you might need a new one.

 

But on a DOHC there are two thermos stats one for the gauge and one for the fans. One or both of those could be bad.

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You're saying that both of them shoul kick on? I never knew that there are 2 Tstats. Where are those 2 that you're talking about, especially the one for the gauge? I just replaced my Tstat which I'm pretty sure the one for the fans or am I wrong?

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the drivers side fan is the primary fan that comes when the engine reaches a certain temp and comes on with the AC. the pass side also can also come on with the AC.

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T-stat = nothing to do with the fans. The T-stat is a mechanical device that opens at a specific temp to allow coolant from the engine back into the radiator.

 

On 93 and older w-bodies there are two coolant temp sensors. One (just underneath the t-stat, actually) is the sensor that tells the ECU when to turn on the fans (I thought the left fan was the primary? Guess it doesn't matter). The second one on the back of the engine is the one that sends the temp to the gauges. It's possible that one (or both) of these sensors has gone bad. The gauge could be reporting an inaccurate temp (have to put a scanner on the ALDL port), or the sensor that turns on the fans is doing it too late (the car will turn on the fans at different temps). It is also possible that one of your fans isn't switching on at all, because either the fan or the fan relay is bad.

 

On 94+ w-bodies there is only ONE temp sensor (that has an extra wire) that controls both fan turn-on temp and gauge temp. It is possible to put a 94+ temp sensor into a 93, but you'd have to route a wire to where the gauge temp sensor originally ran.

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Thank You very much. I'm taking the driver side fan and test it and if it works, I'll check both sensors and depending on how much they cost, I might just go ahead and replace them especially the one behind the engine.:thumbsup:

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To save you some time wondering if the fans do function, you can ground the ALDL circuit with a paperclip, ignition to *on*, and the fans should engage as the ECM circuit is in *diagnostic* mode.

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