When I bought the car the heater temp was full hot, this forum gave me the know how to strip/clean the duo valve. Been perfect up to now, now its back to full hot. I thought the duo valve would be ok so I've been checking other stuff, fuses, cabin temp sensor and vacuum, heater controls etc. After no joy I finally tested duo valve. 12v battery across both sides, 1 clicked, 1 didn't. Checked resistance, The good one is 17 ohms, The other is only 2 ohms. Took it apart and it looks like water has got into the coil. I'm going to refit it and leave it unplugged until I source a used one from a breakers or Ebay or somewhere. Not too much of an hardship this weather. Question, what is the other motor alongside the duo valve [ car is 93 e320 coupe and should I leave that unplugged while duo valve is unplugged.