Noticed cold air coming from the dash vents with the A/C switched off.

Dealer says the A/C compressor is always on in the background and must use the floor vents to get outside air.

This does not sound right. Not the same on 1999 SD.

 

It is correct, they run the compressor every now and then in order to keep the AC system lubed up an to prevent seals from drying out. You should be able to adjust the temperature a little warmer if it is blowing too cold, or turn the system off altogether.

 

Interesting...So if the switch is on OFF, you still get air through the vents? Maybe it is small and I didn't notice, but it doesn't seem like mine does that.


DOH! NM....I re-read your post....on anything but OFF. DUH

 

Yeah, the AC runs in every position but off and floor I believe. You shouldn't feel any air out of the vents at all when it is in the off position. I guess I could have explained it a little better, sorry.

 

On the higher end vehicles, the explanation is that the AC helps dry out the air in the cabin which makes it more comfortable, so they run the AC all the time whenever the climate control is on. On my Lincoln this is the case but you can turn it off with the AC button push button. Similar on my Wife's Mercury too.

I would guess on vehicles with a plain old fashioned heater/AC maybe the AC isn't on unless it is in AC or Defrost.

Just the explanation given me on the Lincoln plus some guessing,

Jim Henderson

 

Thx for the feedback.

Using the fan switch only on low; a/c off, and have cold air coming from the middle vents. Going to a horse show early tomorrow and will check again. Wife is showing, I'll look at the babes.

We have had a month of high humidity, warm temperatures and heavy rain. Ohh, that's right . . . it's August in the midwest. The mosquitos will be as big as robins this weekend.

 

The a/c compressor runs in every position except OFF, PANEL and FLOOR.

 

It is RARE that the A/C can be turned off, or will remain off, in any of defrost/demist/defog positions. In many modern day vehicles there will be no actual indication of the A/C being operational in this mode.

In the past I always disconnected the A/C compressor clutch connection during the months when cooling wasn't really needed and operation of the A/C might or might not (mostly NOT!) be functional for dehumidification of the cabin airflow, but ALWAYS has the potential of being EXTREMELY HAZARDOUS.