AC turns on with heater ??????

[1Reaper]

Every time I turn on my defrost of heater the AC comes on too. Even when the temp is set to 90 degrees.

How do I get it to stop doing this or is something wrong?

Thanks

[jimmm]

I was told some cars do that to pre dry the air before heating it to make it work better as a defroster.A by product of AC is dry air.Also the heater runs all the time even when your using the AC, some companys sell a valve to unhook this feature and make the AC colder.Not sure what the reasoning is for this.

[1Reaper]

That seems like a waste, can anyone else verify that the AC kicks on with the heater or defrost on their 2006?

[artsamm]

Originally Posted by 1Reaper

Every time I turn on my defrost of heater the AC comes on too. Even when the temp is set to 90 degrees.

How do I get it to stop doing this or is something wrong?

Thanks

Has been normal to come on during defrost on any vehicle I've had. have not checked my 2004.
For dry air reason as mentioned. To send dehumidified air to windshield.

[1Reaper]

Doesnt AC kill fuel mileage? Is it that big of a deal?

[00forddiesel]

It may affect fuel mileage slightly. It is normal on most vehicles for the AC to kick on with the defroster to dry the air. It should not be on with just the heat, only when switched to defroster.

[superxcrewfx4]

The preset locatons for the ac to turn on automatically is AC, MAX AC, Foot and Floor combo, Defrost and Floor Combo and Defrost

You can disable this by disconnecting the magnet on the ac compressor if you dont want it to come on.

[joegoodrich]

On my 06, my AC comes on any time I use the 'auto' feature of the digital climate control. It doesn't matter if I set the temperature to 90, the display still shows AC.

I haven't checked under the hood to see if the AC compressor is actually engaged.

[Banshee365]

The clutch engaging on a 6.0 V8 diesel isn't going to affect it much fuel mileage wise like it would on a 100 hp 1.5L 4 banger.

[alwil]

Originally Posted by superxcrewfx4

The preset locatons for the ac to turn on automatically is AC, MAX AC, Foot and Floor combo, Defrost and Floor Combo and Defrost

You can disable this by disconnecting the magnet on the ac compressor if you dont want it to come on.

Or you can switch it to the vent and foot combo right above the A/C setting, mine does not engage while its on this setting ever.