Compressor Running on defrost?

[andy2005]

2001 Ram 5.9L; when the climate controll is set to either "defrost" or "floor and defrost" there is a puddle of water underneath it when I park it, as if the A/C has been running. Does this mean the compressor still running?, and if so is this normal?

[fredjacksonsan]

Yup, it's normal. That's to assist in defogging the windshield during cold and rainy days.

[andy2005]

Thanks, I kinda thought it might be normal to assist in removing humidity thus helping the de-fogging process.

[fanworks]

This is a common feature and goes back a fair ways. My 1990 does this, but I found a way to get it to run defrost without turning on the A/C system. (Push in the defrost select button, then once the vaccum switch has selected it, pull it back out. The buttons only push into select to pulling the tab back out does nothing other than disengage the electric switch for the A/C system to cycle.