Radiator fan will not come on

Which fan motor relay ? Cooling (radiator) fan or the heater / A/C blower motor relay ? If talking about heater / A/C blower motor it doesn't have a relay . It's computer controlled .
Late 90 Cadillac No HVAC Blower Output

Replace the fan relays. The Radiator Cooling Fan Motor Relay is located: Under hood, driver side, front side of strut tower, mounted in relay panel
Application:
High speed The Radiator Cooling Fan Motor Relay is located: Under hood, driver side, front side of strut tower, mounted in relay panel
Application:
Low speed,here's a new part.
http://www.autozone.com/cooling-heating-and-climate-control/relay-radiator-cooling-fan-motor/duralast-relay-radiator-cooling-fan-motor/plymouth/voyager-2wd/1996/6-cylinders-3-3-0l-mfi/412240_0_0

• Relays carry high-amperage current controlled by a low-current switch
• When a faulty relay is not replaced, the circuit will either be non-functional or remain engaged. here's your relay you need.

http://www.autozone.com/cooling-heating-and-climate-control/relay-radiator-cooling-fan-motor/duralast-relay-radiator-cooling-fan-motor/oldsmobile/alero/1999/4-cylinders-t-2-4l-sfi-dohc/221833_0_0

What fan? interior or radiator cooling?

The computer turns on the relay to power the fan motor.
You would need to test the relay to see if it is powering the fan and check the ground circuit for the fan motor too.
Could be a faulty fan motor, relay, or wiring problem.

Ok. The way your system is set up,you have a fan switch located in the engine block,usually near the top.That fan swtich sends the voltage to the fan motor or to a fan relay then to the motor.You can jump the fan motor directly to make sure the motor itself is not burned out by unplugging the motor and running a jumper wire from your battery pos terminal to the terminals on the fan motor itself..If you have checked the motor and it does work,then the easiest thing to do is simply replace the fan switch.You should have a Coolant temp switch and a radiator fan switch and possibly and Radiator fan relay.I would try the radiator switch first,then replace the relay.The coolant temp sensor is for the computer and usually doesnt tie into the radiator fan switch.try that and repost.Good luck

Hi,
The problem would be the radiator cooling fan.

• Check first the relay, interchange that relay from similar one in the fuse box in the engine compartment.
• Check the radiator fan motor, pull down the fan motor and directly connect it to the battery.
• Check the cooling fan thermo switch, it is located underneath/side of the radiator assembly. To check it, just get a paper clip and short the socket connector, fan should run if not the relay has a problem or the fan motor is already malfunctioning.

Hope that helps you out.
Tanks for asking FixYa!

Turbo Radiator Fan

The radiator cooling fan is a variable speed electric motor driven fan. The radiator fan assembly includes an electric motor, fan blade, and a support shroud that is attached to the radiator. The radiator fan is serviced as an assembly (fan motor/fan/shroud).

The variable speed radiator fan is controlled by the Powertrain Control Module (PCM) by way of a Pulse Width Modulated (PWM) signal. The duty cycle ranges from 30% for low speed operation then ramps-up to 100% for high-speed operation. This fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C performance, better engine cooling, and additional vehicle power.

To control radiator fan operation, the PCM looks at inputs from:

Engine coolant temperature
A/C pressure transducer
Ambient temperature
Vehicle speed
Transmission oil temperature (automatic transmission only

HENCE CHECK THE PCM

under hood fuse/relay box - #13 7.5 AMP fuse, controles Power mirrors, ABS system, Air delivery, Blower motor relay, Rear window defogger relay, Radiator fan relay, Condenser fan relay

#13 is top row of fuses 3rd from left side.

Radiator Fan Relay located right Rear Corner of Engine Compartment
3 black relays in a row, radiator fan relay 1st one on left side of box

This sounds like the cooling fan motor was the real problem, when it does this the motor is partially shorted, this overheats the new fan relay and will burn it out, I think most likely they should have caught this when the fan relay was replaced, now the motor and the relay should be replaced, as the new relay may be damaged. Also make sure the electrical connector to the fan motor is not burnt, if it is then replace it along with the motor.