I have a simple question about the functioning of A/C unit. Does a/c and temperature controls function as one unit or independently. I mean I can turn a/c on and set the temperature to what I want; but if I turn a/c off I can still set the temperature???
Does a/c control cooling only or it controls both heating and cooling? Thanks.

 

The temperature setting is independent of the A/C. That said, if the temperature you set is below the ambient temperature and the A/C is switched off, the system will not cool the car's interior to the set temperature.

You should also be aware that the A/Cs evaporator helps remove moisture from the air inside the cabin. With the A/C off, you might see a buildup of moisture on the inside of your windows.

 

You need to go to MBUSA to ask this question. The M-B systems are very confusing and complicated and only MB (if even they) knows how they operate. What is off? On mine, I can push the OFF button and everything is off, but if I hit the temp button the HVAC system is engaged. This means both heat and A/C. A/C is always on if system is on, even in 210 degree cold weather when heat is on.
I can push OFF, then turn fan on, but this turns A/C on again. So I push A/C button and theoretically A/C is off. However, if it gets cold, the heat comes on. If I adjust temp, A/C comes back on.
Almost all cars sold today have a system where AC is always unless directly turned off, even when heat is on.

 

A/C stands for "Air Conditioning" if you think of it as the name implies then it is not cosmic at all.
That’s all it does, you either want the fan on with the air conditioned or you just want the fan blowing ambient or heated air.
It is not confusing or complicated no matter who makes it. lol

 

It can be very complicated depending upon how function was programmed. I have a 2011 Toyota and a 2005 Toyota. In those, I can turn on the fan and open the vents. If I want A/C, I push in the AC button.
However, in my 2010 E, there is NO vent only selection. Have to go through process I described above and even then, the computer will often take over to produce heat when it gets cold. BTW, there is NO heat button!
Had a Hyundai where if you turned off AUTO and then turned on AC and then turned AC off, you had a vent only function and could use the fan. System never overrode it. This was not in the manual.
For some reason, MB and some other companies want the compressor to be "on" at all times.

 

Sounds like you're overthinking this. It's really simple - if the A/C is switched off, the A/C compressor will not engage and the HVAC system will provide only ambient air (i.e. vent). If the temperature is set higher than the ambient temperature the HVAC system will provide heat. Nothing complicated about that. Keep in mind that with the A/C switched off, the evaporator isn't working to remove excess moisture from the cabin so the inside of the windows may fog up.

 

I don't know why people don't just set the HVAC to a comfortable temp and let the computer do it's thing.

For me, when I pick up the car, I set my side to 21 and my wife's to 22 and the kid in the back to 23. Haven't touched them for 6000 kms (6 months) and it heats when it is cold inside the cabin and cools when it is too hot in the cabin.

Why pay and have auto HVAC controls when you constantly manipulate them? The car will blow hot air only when the coolant has reached the right temp. Running the fan on High and setting the temp to the Highest value will not heat the car faster. You are just likely to overshoot your desired temp and then have to cool the cabin because you are sweating.

 

In my experience, a car with an 'auto' setting where you set a desired temperature will always turn on the AC so it can achieve any desired temperature as quickly as possible.

The cars I've seen where you manually choose to turn the AC on or off are not automatic climate control. They have dials/adjustors for temp and fan speed and you decide when AC is needed or not.

 

I'm not sure what you are talking about.


In my car I keep it on AUTO basically at all times. But I have experienced with it. If I touch the MODE button the AUTO goes OFF. Then I can select where the air comes out with the MODE button and control the blower speed with the blower speed button. I can also hit the A/C button to turn the compressor OFF if I want to.


What in this is complicated?

 

Hmmm... switching off the the A/C compressor does not mean the HVAC is not automatic. the system remains in auto mode and will continue to maintain the temperature set for each zone. It will NOT engage the A/C compressor if the temperature in a zone is above the temperature set for that zone. That's just the way it works. That doesn't mean it's not an automatic climate control system - it just means it's a smarter automatic climate control system.

 

Incorrect! The AC is always on to prevent your windows from fogging up.
The automakers have not implemented a window fog detector system... Those lazy engineers!

You would think that such a technology isn't needed but after reading a couple posts in this thread it seems that we absolutely need this tech so that car air conditioning can finally become "complicated."

 

My bad for not being specific enough. I meant to draw a distinction between an auto system and a manual system where you are making all the adjustments, but did not go into enough detail on the auto system. You can turn AC on/off on an auto system but the system will turn AC on by default when you turn auto on. Of course, with the AC off, the auto system may not be able to reach the desired temp.

 

Not sure what you mean by "the AC is always on". When the AUTO button is pressed the AC button light comes ON but it does not mean that the AC compressor runs at all times as it runs only as needed. The light on the button means that the AC compressor is available for the system to use if needed for temperature control. If you turn it off the system still controls the temperature but without AC compressor cannot do the cooling function.

Defrost and AC MAX are the modes that keep the AC compressor running constantly.

 

You have to find this out and know it. No where in the very lengthy manual does it explain how to activate only the vents. Normally I just leave it on Auto anyway.
In mine, I have to push the OFF button, then push the MODE or FAN button, but this turns the AC back on. So I have to push the AC button to turn compressor off. Then I can use mode or fan as I want. However, the "heat" will come on if it gets cooler than the temp set on the "thermostat."
It would probably too complicated for the engineers to figure out, but it would be nice if there was a Vent Only button.
If you leave it in Auto, kind of doesn't make sense to put the windows down or fully open the sunroof.
Now, let's beat this dog some more!

 

I give up. I am going to leave the climate control off and just open the windows - the way Mother Nature intended.