For the past 2 years, maybe 1/2 a dozen times, all occurring when ambient temp is over 80*, the climate control has exhibited some sort of confusion. I will typically ride with it set to 74* during these events, and then as it gets a bit chilly after cruising around with it running the whole time, I'll notch it up to 77* and the whole system will start blowing hot air, on the lowest fan speed. At that point, I'll crank it back down to 74* and nothing will change. So I crank the fan speed alone, and it blows hot air still, and the fan doesn't speed up. The only way I've gotten it out of this state is to put it down to 59* (as low as it will go) and crank the fan. Then, inevitably, 30-60 seconds later, it starts rushing out ice-cold air.

Climate control module in the dash was replaced under Starmark 2 years ago because they couldn't find a legit fault. MY feeling is that it must have to do with a failing interior temp sensor (located at sunroof switch??) I suggested this but I was blown off at the time. Any ideas?

The odd thing is, it ONLY has occurred going from 74 to 77. I've never had it happen going from 68-72, etc. Bizarre

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL

That & all MB A/C/C systems are designed to keep the car with-in 3 deg F of the setting at face level after 10 minutes. The in-car sensor is responsible for that job.

I agree with you..most likely a bad in-car sensor(motor).

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Ok, cool....where is this sensor and what's it called? My UK-based Haynes manual shows nothing about it. What's involved in changing it out? Thanks!

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL