Re: [MBZ] cycling hot/cold in 90's w124 300TDt

[Peter Frederick]

Ocsillating temp is usually caused by a bad temp sensor blower, so that 
the cabin air isn't being pulled past the sensor -- car has to be 
pretty warm before the sensor heats up, then gets pretty cold before it 
cools off.

I'm not familiar with the dual control system, but I'd bet you have two 
temp sensors, and the suction blower (located under the right hand 
outer dash vent on the single control systems) is bad, or the hose has 
fallen off.

Peter