Trying to help out a friend with a 1992 stealth DOHC NA engine. The car as he bought it had a radiator zip tied in that was not to the stealth. The fan was hot wired in as well. They had a relay near the front, but I'm not sure how that was hooked up.
Ended up with a donor car that had a good fan setup, but the radiator was busted, so we got a new radiator from NAPA and swapped everything over. The plugs and sockets all seemed to be where they should be and intact, nothing cut.
We also swapped in the engine and transmission from the donor car. Fired up the engine and waited for the hoses to get hot. Both the inlet and outlet got quite hot but the fans never started.
First thing I'm going to have the friend check is the fuses under the dash. We didn't have a chance to check that out as we ran out of time last night fighting other battles.
Does any one have a wiring diagram (or pointer to one) for the cooling system? Can anyone explain how it should work?
My guess is there is a sensor near the t-stat, that somehow tells the fans to run. Then based on the sensor on the radiator the fan either runs in hi/low mode through the relay/resistor. Is the second fan just for the A/C?
According to my 1991 service manual CD, the radiator fan motor has a high speed and a low speed. There is a high speed relay and a low speed relay both of which are controlled by the engine controller which grounds the relays for the respective speed. Apparently vehicle speed (to a minor extent) and engine temperture are factors the engine controller uses when determining which speed the fan is to operate.
According to the chart in the service manual, on page 7-8, the low speed radiator fan relay is grounded by the ECU anytime the coolant temp exceeds 203 degrees F and the ECU energizes the high speed relay anytime the coolant temp exceeds 221 degrees F. Both relays are energized on high speed. I'd think the fans would turn on at a lower temp but apparently not.
The DOHC thermostat begins to open at 180F and is fully open at 194F - - surprisingly both the SOHC numbers are about ten degrees higher.
There two coolant temp sensors, both of which are located in the thermostat housing close to the water filler cap. The smaller sensor is for the temp gauge and the larger of the two is for the engine controller to do it's thing.
Both the radiator fan and condensor fan are fed by fusible link #5 (location unknown) so that might be importent especially because of the previous owner's cobble job on the cooling system.
The ground for the motor itself is under the fender just in front of the strut - - probably have to remove the splash shield to see it. One electrical diagram says it's on the left and another diagram says it's on the right.
Looks like the problem was no 30 amp heater fuse. The temp gage never went above 1/2 way. I was checking the A/C and when I went to see if the compressor kicked in, I noticed both fans were on. Hopefully that was it. I'll know once we figure out how to get the passenger side 1/2 to seat correctly.
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