G. Auxiliary Fan and Control of Auxiliary Fan

M4 Auxiliary fan


Models 201.022/023/024 up to 01/89 and model 201.122 are equipped with a small electric auxiliary fan. The current consumption at 13 V is approx. 13.5 amps.







M4 Auxiliary fan


Model 201.024 as of 02/89 and models 201.028/034/126 are equipped with a large electric auxiliary fan. The current consumption at top speed and 13 volts is approx. 17.5 amps.







M4m1 Auxiliary fan, left
M4m2 Auxiliary fan, right


Models 201.029/128 are equipped with 2 electric auxiliary fans. They are both actuated simultaneously. The current consumption of both fans at top speed and a battery voltage of 13 volts is approx. 26 amps. The auxiliary fans are mounted directly on the condenser.


Actuation of the auxiliary fan







a) In vehicles with small auxiliary fan. At a refrigerant pressure of 20 bar (as of 09/88 at 16 bar). the pressure switch (S32) switches on the auxiliary fan and the engine fan via the double contact relay (K8); the fans are switched off at approx. 15 bar (as of 09/88 at 12 bar).

K8/1, K9 Auxiliary Fan Relay:

K8 Double contact relay: Black cover
K8/1 NO relay: Black housing
K9 NO relay: Blue cover
K10 Preresistor relay: Silver


b) In vehicles with large auxiliary fan or with 2 small auxiliary fans, actuation occurs in 2 stages:
1st stage by the pressure switch (S32), at a refrigerant pressure of 20 bar (as of 09/88 at 16 bar) via the relay (K8 or K10) and via the preresistor (R15).
2nd stage by the temperature switch (S25/4). at a coolant temperature of 100 °C or (S25/5) 105 °C via the relay (K8/ or K9) directly.


The arrangement of auxiliary fan relays depends on the vehicle model and version.







S25/4 100/110 °C temperature switch in models 201.024 J, AUS and 201.028







S25/5 105/115 °C temperature switch in models 201.034/035







S25/5 105/115 °C temperature switch in models 201.029







S25/5 105/115 °C temperature switch in models 201.126 and 201.128