I have a 2008 Mercedes Benz auto, 2148cc. The heating and a/c have been working fine for several years, until a few months ago.
The initial problem was that the cold a/c switched itself off intermittently, but when you noticed it getting warmer and switched it back on again, it was fine.
But now there is an intermittent problem with the heating. I like the warmth on my feet and the car heats up fine after a few miles. The thermometer reading on the dash is fine also, and stays where it’s supposed to, midway.
But as soon as I use the blower on the window screen for a few seconds to demist it, the heat on my feet blows cold and stays cold, even after turning off the window screen blower, and won’t heat up again.
Any suggestions please?