rkhan20907

I'm having a slight issue that I would appreciate some guidance on from the experts please. I have an E 350 MB. I turned the heating on in my car today, and noticed that the AC button was on, which I tried turning off by selecting it, but it won't shut off. I've cycled through setting temp on high and low and auto and this and that and every thing I can think of. Pls advise what to do? I don't know, is it an issue to run the heater when the AC light is on. I turned the temp from high to low to see if the AC is on and working and the air goes from hot to cool so that tells me the AC is on and working. Plus the display also tells me the AC is on.

Can someone please help?

choitwao

AC = cool + heat no?

ItalianJoe1

The car runs the compressor to keep the humidity down inside the car, even with the heat on. Normal operation, as long as you are getting the hot air you request.

Arrie

ItalianJoe1

Well, if you set it to defrost, the a/c compressor runs by default. Might be similar with the heating function? I don't know, haven't personally tried it. Very little use of the heat in the weather down here.

Arrie

Definitely I can toggle the A/C button ON and OFF every time I press it. Interestingly if I put it to MAX COOL the A/C light goes OFF but it still runs compressor and cools.

obwielnls

The AC should stay on year round. It keeps the humidity down in the car and prevents fogging. As to your question, there are times when the system will run the AC compressor no matter how you have it set. Defrost is one of those times but there are more.

P.S. The AC compressor will NOT keep the heater from working as intended. Turning it off will not make the car get warmer faster.