Heater AND Air Conditioner??
 

Hi all,

Have always gotten a lot reading this forum and I appreciate any help on this.

I have a 2009 Base Model 370Z. To use the heater with recirculated air (no outside air circulating), I need the air conditioner on as well. The car will let me turn off AC only when I switch to outside air. I use the recirc air sometimes when there's smoke, etc in the air when driving on the highway. This is regardless of what air flow (center vents, defrost, etc) I use.

The dealer says this is by design, but it makes no sense to me to use up whatever refrigerant the AC uses in the dead of winter to heat my car.

Am I missing something? I checked the manual and it gave no answers. I have the "Type A" AC / Heating setup with a middle dial that sets temperature.

KZJ

You're correct, for Recirculate to be on, the A/C needs to be on as well.

I just leave mine with both of those on and mess with the temp. Occasionally I'll hit the dial to defrost for an icy windshield but that's it.

Most of the cars nor days are designed like that, my old lady SUV is the same and is a Toyota (not in the recalled list).

Whether the A/C light is on or not, the heater will still work the same, the only difference is the outside air recirculation. When the A/C light is on, that means the A/C compressor has been turned on. But, the compressor will only cycle on and off if the temp has been changed to cold. Otherwise, the blend door will open to the heater core and let only heat in. Temps between full cold and full heat are controlled by the blend door motor, which turns a door in side the dash to let a mixture of cold air, from the evaporator, and heat, from the heater core, blend together to create your desired temp, which is controlled by the thermostat in the A/C system. This is good info for anyone who cares to know how the A/C system functions!

I was under the impression that the compressor does cycle to some degree to dehumidify even if the temp is not set to cold. I've been wrong before----today! lol

It will cycle, depending on your desired temp. Cold - cycle often; Warm - cycle less often. The dehumidifying effect is really a matter of not so much of the A/C system, but the clash between air coming from the A/C system and the air in the cabin. On a hot day, the cold, dry air from the A/C system will dry out the air in the cabin. And on the other hand, on a cold day, heat from the heater core may carry more humidity than the air in the cabin, causing some fogging. The scant participation by the compressor's cold air hardly has an effect on the heater's hot air, so it will still be humid, but that is if it is more humid than the air in the cabin.

It is really all a matter of outside humidity levels as to the effect the A/C has on humidifying.

It is tough to answer these questions without writing a novel, haha!!