Still working on the 89 190E. I am having a problem with the climate control system. Here's what it is doing. When you first start the car, it heats up just fine. As long as you are driving around town, the heat works OK. However, when you get out on the highway, within about 15 minutes it goes cold and then reacts at times to where it goes full hot. Then it start cycling between no heat and full heat with no in between. Then at times, it will go full cold and the fan will stop working. After pushing several buttons, it will start working again and the heat will go full hot again for a short time before shutting down again. I have replaced the Climate Control Unit and the heater valve. what else could be causing this problem?

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83 W123 240D
76 300D, "Lil Yellow Car"
1978 Cessna 172N 180 HP Mod

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