My trucks fan/air conditioning when set to either Top/Bottom blow or Defrost, turns the A/C on.

Is this suppose to happen? I thought the A/C only turned on at A/C.

This is a late question, I noticed it this summer after getting the A/C fixed, and just really didn't care because I had cold A/C in my truck, lol.

 

The ac works in all settings but floor only and vent only.

 

It makes sense that it runs with defrost (dehumidification), but drives me nuts that it runs when you have the floor heat on. I was thinking of installing a manual bypass switch for the compressor.

 

Floor only no ac, and its been done.

 

There is a how to on the manual sw, I think !

 

Floor only Vent only = no A/C compressor...

All other settings on the hvac dial run the A/C compressor

 

I don't know about you guy's trucks but I am pretty sure on my truck only the vent and the off position do not kick the A/C on.

 

This is why i like my Gen 3.
Only Defrost and A/C turn the compressor on.