Neon L4-2.0L VIN C (1997)
Condenser Fan Motor Relay: Description and Operation
Radiator Fan Control Module -PCM Output
The radiator fan runs when coolant temperature and A/C system pressure demand cooling. The radiator fan circuit contains a Pulse Width Module
(PWM) this is shown on the wiring as the Solid State Fan Relay.
A 5 volt signal is supplied to the PWM. The PCM provides a pulsed ground for the PWM. Depending upon the amount of pulse on time, the PWM
puts out a proportional voltage to the fan motor at the lower speed. For instance, if the on time is 30 percent, then the voltage to the fan motor will be
3.6 volts.
When engine coolant reaches approximately 99°C (210°F) the PCM grounds the PWM relay. When the PCM grounds the relay it operates at a 30%
duty cycle and immediately ramps up to 100% duty cycle. The PCM de-energizes the PWM relay when coolant temperature drops to approximately
93°C (199°F).
Also, when the air conditioning pressure switch closes, the PCM grounds the PWM. The air conditioning switch closes at 285 psi ± 10 psi. When air
conditioning pressure drops approximately 40 psi, the pressure switch opens and the fan turns off.
The PWM relay is located on the left front inner frame just behind the radiator.
