ramshyd

a) Do I need to run the car on 'Auto' climate control for heating? or can I shut off the A/C manually and just turn on the fan for hot air? What difference does turning on the Auto makes here?

b) If the Auto is turned on, does the compressor run always? will it be a load on the engine and fuel efficiency? I thought in winters, i can safely turn the A/C off, and use the fan and temperature buttons to control the heating. This might provide more engine power, and probable better economy?!?

Advice please!

Thanks

Rainbird

I have used nothing but manual A/C and heating. I use the climate screen on the navigation screen to control the fan speed and the temperature buttons for heating. I also mostly run in the recirculation mode. Not sure on the compressor question and will leave that for someone else.

draco

I run mine all the time. I feel it's better to run something that is still being turned by the engine, rather than it sitting there as a dead weight. If you turn off the A/C button it makes a difference to the heating. The air is not dehumidified so it gets quite hot without the A/C on. I tend to have my compressor on all the time and mostly on Auto. The temperature I will adjust as I need to. I find it's much more comfortable with the A/C on.

Only thing I wish I could do is shut off the centre vents, which you can't really do (they have to be pointed up and away but they are still "active").

lexusfan05

The compressor does not always run. It has a "clutch" that engages and disengages the compressor as needed when ac is turned on. When ac is turned off, it never engages. When compressor is disengaged, the only thing that always spins is the wheel that is driven by the belt.

tfischer

For defrosting the windshield, you need the compressor to run so the air is de-humidified.
I usually run the car in the "Auto" mode, unless I want to change the fan speed for some reason, or in case I want to turn the whole system off (and open the windows on a nice day). I do not notice any difference in performance, and my 330 engine is smaller than the 350 engines. Fuel economy is probably effected, especially in the summer, but you don't get all that nice cool air for free.
The "Auto" setting is a marvelous convenience feature that won't turn on the heater if the engine is not warm enough, and smart enough to adjust the fan speed for reasonably rapid heating and cooling, and will even let the passenger change the temp on the right side of the car. You can do all of this manually, of course, but I'm either lazy or just to tired and old and stupid to waste time on that stuff when I just paid for a machine that will do it for me.
Just push "Auto," be sure the little green light is on, and drive away.

rcy

The compressor also will not run if the ambient temperature is below a certain point (usually around freezing) to prevent damaging it. It won't matter at this point if you have it in AUTO or DEF or if you have manually turned the A/C on..it just won't engage the compressor.

As an aside, if you choose to turn the A/C off manually, it's a good idea to run it once a week for 10 mins or so to keep the lubricant circulating and help prevent your seals and o-rings from drying out.

ramshyd

Great points here specially the last one from rcy.

If the economy isn't largely affected by the compressor running, I am going to keep the Auto setting always..

Thank you!! Have a nice weekend ahead!!!

glassmanj

FYI- just to the right of the steering wheel where the dash curved downward you'll see about an inch square with several horizontal slots on it. this is the thermocouple sensor that reads ambient temp. if you ever feel your temp dial seems off use a blast of air to remove any dust that may have built up.

ramshyd

Thanks for this information. Actually i was looking to post this as a new question - but you read my mind!!