Primary fan won't come on, overheats

[Boogerbub]

Hey fellas,
The primary fan on my '86 won't come on. The subcool fan works fine. I have checked the relay and it is good. I have jumered the relay out and the primary fan works just fine, so I know the fan is good also. I have also jumperd out the temp sensor at the gooseneck, this should have started the fan- but it didn't. The sensor seems fine, the fan is fine, and the relay is fine. What else is there? Is there something between the temp sensor and the relay that could be bad?
Thanks for any help,
JP

[Mac]

The temp sensor for the fan is on the bottom of the radiator. Is that the one you jumped out? Also check the thermostat, it might be stuck.

[Boogerbub]

Sweet. Thanks Mac- I jumped out the sensor at the bottom of the radiator just now and the fans fired right up. So, what are the sensors up on the goosneck for? There are two of them side by side. I figured one was for the primary fan and one for the subcool fan. One of them did in fact turn on the subcool fan. Got any ideas?

[hondamanlxi]

if your EFI, there are 3 sensors side by side. One is the ECT and is vital to your ecu! Another is a fan switch, the single wire one sends a signal to your gauge.

[Mac]

Make sure that the thermostat is good before you change the sensor. If the t stat is stuck closed hot coolant will never get to the sensor to turn on the fan.

[smufguy]

the efi has three temperature sendors. the one on the bottom of the radiator is for your primary fan. The green sensor on the thermostat is for your secondary fan (it clicks in at a higher temperature if the primary fails), the black/or white sensor is for the ecu signal and the single wire (like mentioned above) is for your temp gauge.

My sensor on the bottom of the radiator is shot, so i just jumped the sensor and put a switch to it so now i just click the fan on whenever i want, it just runs constantly all the time after the car warms up.