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Cooling Fans

Joined
Aug 8, 2007
Messages
22
Location
Duluth, Ga
Corvette
1990 Steel Blue Corvette FX3
I seem to be having a problem with my cooling fan. I just replaced the thermostat and now if you sit in traffic, the fans will not kick on. I am trying to figure out if it would be because I bypassed the Heater Core (it is clogged). When I turn on my AC the main fan will come on, but not the secondary. Otherwise no fans will come on.

Trying to figure out if there is a temp switch on the heater core or something. I am going to replace the relay's and the Fan temp switch and see what happens. Also, is it typical of these cars to "when sitting" to heat up until the fan temp switch tells the fans to come on?
 
I seem to be having a problem with my cooling fan. I just replaced the thermostat and now if you sit in traffic, the fans will not kick on. I am trying to figure out if it would be because I bypassed the Heater Core (it is clogged). When I turn on my AC the main fan will come on, but not the secondary. Otherwise no fans will come on.

Trying to figure out if there is a temp switch on the heater core or something. I am going to replace the relay's and the Fan temp switch and see what happens. Also, is it typical of these cars to "when sitting" to heat up until the fan temp switch tells the fans to come on?

I haven't had my '90 hot enough for the secondary fan to come on, so I don't even know if it works:W.
I think that the main fan will not engage unless the temp is at 228* ( someone correct me if I'm wrong), so you may not be hot enough.
A quick way to verify that your gage is reading accurately is to use your HVAC display. (This only works if you have the electronic controller.) Hold both fan speed buttons down until -00 shows on the display. Using the right fan button, scroll up to -16, then press AUTO. This will display the temp in Centigrade, which you then convert. Mine usually stays at 94 - 95* C, but has been known to raise to 110* while idling. Once the main fan kicks in, the temps drop

I'm at work now, so I don't have access to my FSM to give you better troubleshooting ideas. If I remember when I get home, I'll add some more info.
 
Hi
The fans are turned on and off at predetermined temps by the ECM and when AC is called for the secondary fans turn on. I don't think the heater core bypass is an issue. Did you use a stock thermostat (195)? Does your temp guage indicate a hot engine.? In a cold climate a 160 thermostat could alow the engine to run cold thus no fans are needed. The system is responding correctly to the temp. of the engine. Keep in mind that L98's are designed to run hot.

Cheers
Gary
 
Thanks, i did not know about that with the auto climate control, that is actually pretty freakin cool. I have a tuned harris performance chip and a 160* thermostat (The lowest outside temp has been 28*). So I know it will sit about 1/4 of an inch above the "100" mark when its in normal operation (car in motion, and warmed up).

Its only when I am sitting in traffic. Usually the fan will kick on just past 200* and will cool it back down to 180 with the car sitting. However, lately the fan has not been coming on, only when it I turn the AC on. Typically when I sit in traffic it will heat up to just past 200*, then the fan(s) will kick on and cool the sucker back to 180ish.

So let me get this right then, the "only" temp sensor for the cooling fans to kcik on is located by the Alternater, below the headers and on the side of the block? I have the FSM's for the car, but not with me. I think the wire goes to the relay I am pretty sure.
 
According to my FSM, the Primary and Secondary fans are controlled by the ECM using input from the A/C, coolant temp sensor and vehicle speed sensor.
The secondary can also be turned on by the switch on the drivers side head between # 1 & 3 cylinders. This switch is a back up to the ECM.
If I'm reading this right, the secondary will not activate until coolant temp is 239* (115 C).
With the 160 thermostat and chip, you probably aren't getting hot enough to reach this point.
Check your FSM on page 6E3-C12-1 for the complete writeup.
 
Thanks man!
 

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