VaSteve

Mine went bad...confirmed it wasn't the relay by doing the clark's test. I see that there's 3 different ones I could order. How do I know which one to get without taking out the old and inspecting it for the #'s?

1986 n/a

Thanks!

GTSilver944

I believe the only difference is the temperature range. Get the lowest temp one if its for track use or a hot climate.

Techno Duck

I think the standard range is 92/105*C. If you run your car in a hotter climate, you can get a lower temp switch which will have the fans turn on quicker. I believe they have 85/95 and a 75/82. I think the 75/82 is way to low unless you run in a very hot area. I just bought a 85/95 for my car.

VaSteve

Doesn't it need to be matched to the thermostat in the water pump or something?

GTSilver944

I believe they are interchangable regardless of what is in there now, so go with whatever temp range suits your needs. I use a 65/60 on my '84 here in Memphis.

5speed300

Where on the temp gauge will the lowest temp fan switch kick on? Right now mine is kicking on about a needle widths above the 3rd white line... too hot for my liking.

8744S

I'm also in the same boat, I just had the Timing belts and WP done and now it runs so much hotter than it did before.

GTSilver944

So if there is the lwarming up section, three lines, then the overheating section, my old one did it at the third line. The 65/60 goes on 1/3-1/2 of the way between the first and second line.

Techno Duck

Where the fans turn on with the gauge reading has many variables. Some things to consider are dirty grounds, old temp senders and inaccurate gauges (more of a problem on later dash cars).

For early cars running a stock rating fan switch, the fans will turn on around 92*C. You have to take into consideration however that the temp gauge is taking its water temp reading of the water exiting the cylinder head and going into the radiator. The thermofan switch takes its reading from above the top of the radiator. So you will probably see slightly higher temps on the gauge before the fans kick on. With my old 924S, the fans would kick on just slightly past the 3rd white line. The temp gauge would then shoot down to a little below the halfway mark.



For the later cars, low speed fans will kick on around 92*C and high speeds will turn on at 105*C



The same thing applies here, the temp gauge will read higher due to where its taking the temp reading from. Something to really consider is the later gauges tend to not be as accurate. If you look at where the needle rests when the car is off, you may notice it is a few ticks below the 'empty' or 'zero' mark on the gauges. An example of this being the fuel gauge. You may notice if you fill up the tank completley, the gauge only reads 3/4 full (or somewhere around there). Turn the car off, and the gauge reads 1/4 below the empty mark. Every late 944 i have seen has had this same exact problem, and i think its just the needle 'un-indexing' itself. The same thing applies for the water temp gauge and volt meter. For some reason the oil pressure needle dosent have this problem as badly. I have not tested this yet with a resistor, so its still speculation. But its the only thing that could cause this problem i think.