Condenser Fan: Description and Operation

Auxiliary Fans (M4m1 & M4m2):

PURPOSE:
- The auxiliary cooling fans, which are located in front of the A/C condenser, provides additional air flow across the condenser and radiator to assist during periods of high thermal load.

OPERATION:
- All model 140 vehicles are equipped with two auxiliary fans. The current draw under operation in the 3rd stage is 35 amperes at 13 volts battery voltage. The auxiliary fans are protected by a 30 ampere fuse in the maxi-fuse box F2.

Refrigerant Pressure Sensor [transmitter] (B12):

- A refrigerant pressure sensor (B12) on the receiver-drier is installed in place of the two previous pressure switches.

Auxiliary Fan Relays (K9, K9/1, K30):

Auxiliary Fan Pre-Resistors (R15, R15/1):

- The ACC pushbutton control unit (N22) receives an input from the sensor (B12) to provide low pressure - high pressure A/C compressor cut-out, and to control the 3 stages of the auxiliary fans.

Auxiliary Fan Switch-points:

Chart - Auxiliary Fan Switch-points:

Coolant Temperature Sensor (B10/8):

In the 1st stage, the auxiliary fans:
- Do not engage at ambient temperatures < +5°C,
- Engage at ambient temperatures > + 10 °C.