DIY: Unlink A/C from Defroster

[barryware]

when the compressor is allowed to run based on the status of the A/C switch or the position of the air selector knob, it won't run for long anyway in the winter. The compressor runs and cycles on and off based on refrigerant pressure.

When it is cold out, the compressor may start but because the refrigerant pressure will be too low based on temperature to continue to run, it will shut itself off. I really do not see the need to disable the operation based on the position of the selector knob.

If it is warm enough, you may want the compressor to run and aid in defogging the windows. If it is cold enough and heat alone will do the job, the compressor isn't going to run anyway.