I know on the Fords, if the temp is below a certain temp (4 degrees C. iirc) the compressor won't kick on with defrost...
In my Fiesta, I monitor the outside temp on the dash and stay away from defrost/feet-defrost if the temp is too warm.
With that said, I'd love to rig up a switch to the compressor.
On my Focus SVT, it was simply a matter of unplugging the two prong electrical connection behind the HVAC knob.
This way if I need the air dried out, I can simply switch on the AC myself.
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