inactiveuser1019

When I get close to my destination, I usually turn off the AC compressor. I've recently noticed that it keeps putting out cold air. Is there a time delay in the AC compressor switch that keeps it on for a while when I turn it off?

Thanks.

Pierre

dalazernet

Hmm, why? I don't think I can honestly say that I've ever ran the ventilation system in these cars without the A/C turned on -- after all, it will only run it if/when needed and to also pull humidity out of the cabinet to prevent moisture/fogging of windows, etc.

Plus, I recall reading a while back that sometimes the W203 got a bit "moldy" inside the vents and leaving the A/C on helped prevent that.

Is there some benefit to turning it off?

Savage c-300

i noticed this in my car too. it even happens when you start off with the AC off. not sure why it does this though.

Carsy

In my opinion ,Yes to save fuel & compressor wear & tear.

jstaneff

You don't say where you are from. If you live in a climate where the defrosters have to work, then the compressor will run since it's used to keep the windows clear.... (Yes, I've run the A.C. when it was cold outside ... dumb, but true!).

Otherwise, the compressor may be off, but the coils in the A.C. are still cold enough that cold air will continue to come out since air blowing across them will naturally be cooled by them.

Now if you turn it off several miles away and it stay on, .....

jangy

All Benzo ACs run on startup and after a few minutes of the switch. Dunno why, but they do.

RLE

In a way, yes. The AC compressor, unlike times past, does not use a clutch Instead, it is a variable swashplate compressor which means that when refrigerant flow (to lower the cabin temp) is called for by the car's main brain, the vanes in the compressor change their angle so as to pump more (or less) refrigerant through the system. When the AC is manually turned off, it takes a little while for the compressor to stop pumping. In the older cars, when the compressor clutch activated, the compressor went from zero speed to full speed (more or less) and that's why we used to be able to feel it turning on and off. And with a clutch, the compressor stopped instantly.

Now you don't feel compressor speed changes at all. I learned about this because my 2001 C320's AC seemed like it wasn't shutting off immediately and it was just the slow shutdown of the compressor.

Warming up the cold system is a small part of it but the main thing is how fast the R134 refrigerant stops flowing.

inactiveuser1019

This is very interesting. I timed it yesterday, and it continued cooling for 5 minutes after I had turned the A/C off.

Pierre

tanktube67

Also every time the window defrost is use the a/c compressor is activated

mac911

Yeah, when I'm about 10 minutes from home I turn off A/C and then about halfway home, the compressor turns off. Fine with me.

Also, I try to turn it off before turning car off, so that the A/C doesn't automatically come on the next time I start the car, if I don't need it, I don't use it cause it does save a little fuel.

Also, auto climate control can work even with A/C off, like in the winter, it works fine.

In the summer, auto without A/C, just blows the fan really hard at you, but sometimes I do that too trying to save fuel. ha-ha.

inactiveuser1019

For "cooling" without A/C, I lower fan speed manually (you have buttons for slower/faster) and turn the thermostat to Cool.

Pierre

mac911

Too much work.

inactiveuser1019

I agree it's work, but it's sometimes nice to feel air that hasn't been cooled, mainly in the Spring and Fall, along with an open sunroof.

Pierre