Hi all
I have an '08 TL with AT and something is puzzling me. When I put the heat on, even up to 85 degrees, it starts out with the A/C compressor on. I can hear it click on, and when I push the 'AC On/Off' button I can hear it click off when the screen says 'AC Off'. If I turn the car off, the compressor stay's off. But if I turn off the heat, the compressor comes back on when I turn the heat back on.
Am I missing something? Why does the compressor need to run with the heat? The defroster is not on, it's just blowing on my feet.

Your help is appreciated.

 

the ac compressor turns on because not only does the evaporator remove the heat, it also removes the moisture from the air, making for a cozy environment. the air flows through the heater core warming it up again. its completly normal. Cheers!

 

IMO The compressor being on when heat is needed is just robbing power/gas mileage and not needed, I always hit my A/C off when desiring warm air.

 

guys, the air compressor can do more than cool down the air, its for humidity purposes also.

an example is when your windshield is fogged up, you need to turn on the AC to defrost it, doesnt matter if its cold or hot air, as long as the AC is on. this is because of the humidity level from the air.


stop hating on the air compressor

 

Don't use the AUTO setting and this won't happen.

 

Thanks all for the information. If you're telling me that is how the car is designed and why it is, then I guess that has answered my question. But I don't really agree with that design choice. I am already aware of the benefits of using the compressor to remove humidity from the air (regardless of its temp) and how it helps clear the windshield. But I feel like I should have to turn the compressor on in those situations, rather than turn it off in every other circumstance.

I agree with ohsixMTee, that it's a waste of power/gas mileage to have the compressor on for every temperature in the climate control. How much power/gas it wastes, who knows and I don't care to debate that. But it just seems backwards to me.

I am not using the Auto setting, SouthernBoy.

 

Then your model year must work differently than my '04 and '05. I don't have the same situation as do you with my TL's.

 

These actually answered my question because I have been wondering the same thing recently

 

I rarely use AUTO anymore anyways. It never seems to push air where I want it, when I want it. In the summer, AUTO never wants to leave the blower on high when it is hot. It never wants to leave recirculate on either. In the winter, it blows more hot air out the vents instead of on my feet or on my windshield. So I just manually change the settings (A/C included) as I see fit to keep me comfy and all is good.

To the OP's original question...just because your windshield isn't fogged now doesn't mean the climate control system shouldn't try to prevent it from getting fogged. How many cars do you see rolling around with the back and side windows all fogged up? That is because their compressor isn't running and the humidity got too high. If you use AUTO through the winter, I doubt you will ever see your rear windows get fogged up heavily.

 

04 TL here, and my compressor also turns on whenever I turn on anything even without using the auto button. Is it possible your a/c is actually running and you just don't know it? The a/c is only off if there is an "a/c off" message on the screen (non-navi model, I'm not sure what the message is on the navi model).

I agree with J. Bourne, this is an unnecessary feature which just uses more fuel and causes extra wear and tear. I wish my TL didn't have automatic climate control.

 

06 with navi here and the AC Off stays there unless I turn off the system then turn it back on. Also, if I push the windshield defog button then the AC kicks on but once I press it again it goes back to the AC Off setting where it was.

 

My '04 TL and my Dad's '00 Accord, both turn on the ac with the heat. Just how Honda did it.

 

This is normal amongst many manufacturers. My Maxima did it and my Ford truck does it. Makes a huge difference is getting rid of fogged up wind shields.

 

Neither my '04 or my '05 TL does this.... unless I use the AUTO setting.

 

Nope, I know exactly what I'm doing with my HVAC. My A/C only comes on when I wanted it to. If I select AUTO, it will activate. But I don't turn on my heat like that. Most of the time, my A/C is not in use so I just increase the temperature and voila.... heat.

And yes, I am well aware of when the compressor is running and when it is not. And yes, I also can see the A/C on or message. BTW, both of my TL's have Nav.

In the cooler months, A/C is not needed to clear the interior of my car because it doesn't fog up. The only time it might is when it's raining and humid outside. Otherwise, it's as clear as ever.

 

I don't know if it applies with Honda but in the past the A/C was activated to circulate the refigerant through the system to prevent the seals from drying out and refrigerant loss. Wasn't uncommon years ago come spring to have no a/c because of that.