Radiator Fan Control Relay
Radiator fan control relay may be referred to as radiator fan control module. Relay is a solid state relay. Relay controls operation of radiator cooling fans. Radiator cooling fans will operate at variable speeds depending on engine coolant temperature and the A/C system pressure. PCM pulses ground (control) circuit to signal requested fan speed. Radiator fan control relay is located behind front grille, riveted to front bumper brace, in front of condenser. See Fig 1 .
Radiator fan control relay receives constant battery voltage from fuse No. 27 (40-amp) in Intelligent Power Module (IPM). The Powertrain Control Module (PCM) controls the ground circuit for radiator fan control relay by using a pulsed (time on) ground. This pulsed ground is known as Pulse Width Modulated (PWM) ground. The PWM ground causes radiator cooling fan relay to produce a proportional output voltage for operating radiator cooling fans at different speeds.
Radiator cooling fans operate at high speed when engine coolant temperature is approximately 230°F (110°C) and then reduces to low speed when engine coolant temperature decreases to approximately 220°F (104°C). Radiator cooling fans will turn off when engine coolant temperature decreases to approximately 214°F (101°C).
When the A/C pressure sensor closes at approximately 300 psi (21.1 kg/cm2 ), radiator cooling fans operate at high speed. When A/C pressure decreases to approximately 250 psi (17.6 kg/cm2 ), A/C pressure sensor opens and radiator cooling fans operate at low speed. Radiator cooling fans will turn off when A/C pressure decreases to approximately 248 psi (17.4 kg/cm2 ).
Radiator cooling fans operate at high speed when transaxle fluid temperature is approximately 232°F (111°C) and then reduces to low speed when transaxle fluid temperature decreases to approximately 204°F (96°C). Radiator cooling fans will turn off when transaxle fluid temperature decreases to approximately 192°F (89°C).