Auxiliary Fan not Running

[Cigar Havana]

On a 1989 420 SEL, (248,000 KM) the auxiliary fan does not turn on when the temperature reads 110. Normally it would turn on at about 105 and stay on until the engine water temp. dropped to 100. I did replace the blue dual pin thermostat on the pipe above the water pump. The coolant is at the correct level. The water pump and thermostat on the pump were replaced about 3 months ago.

Another odd event is occurring, but I'm not sure it is related. When first starting the car, the AC compressor keeps cycling on and off when the inside temp is well above the requested temp. I would have thought the compressor would stay on steady until the desired temperature is reached. A hose from the dryer to the evaporator was replaced about 2 months ago and the system was filled to proper capacity. The system has been converted to 134a.

Any ideas on how to diagnose the problem?