1988 Chevrolet Celebrity Fan does not work

[elevator]

I replaced the relay in front of the car above the right
headlight, and the temperature sensor on the thermostat
assembly, the fan tested ok, but the fan will not turn on
when the car gets hot, so the car heats up when I go up hill.
I need to get out of this town once in a while, please help.

[KATAZ]

at Times When You Replace The Temperature Sensor The Temperature Sensor You Buy Is An Aftermarket Product And They Tend To Turn The Fan On At A Hotter Temperature Instead Of The Original Factory Setting, You May Want To Check That, Also At Times On Some Of These Cars The Fan Tends To Have A Heating Coil/sensor Placed In Back Of The Fan Clutch, At Times Its Not The Temperature Sensor Or The Relay At Times Its Just The Fan Heating Coil/sensor In Back Of The Fan Cluth, Check To See If Thats It, Because That May Be The Problem, Peace

[elevator]

I have checked the fuse, replaced the heat sensor at the thermostat, replaced the relay, tested the fan with direct 12 volt connection, and at a friends request, I turned on the Air Conditioning. He said that, that the fan should come on with the AC because it bypasses the computer. But, the fan does not turn on. Must be a wiring problem. Does anyone have a troubleshooting instructions or idea?