engine surge when heater fan is on. I can hear a relay switch on and off.
Jan 13, 2011 at 6:39 AM
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JACOBANDNICKOLAS
✓Experienced Mechanic
110,248 POSTS
What I believe you are hearing is the ac compressor cycling. When you run the defroster, the AC runs to dehumidify the air entering the vehicle. Does it feel like in the summer when you run the AC only?