Reduced keyless entry range, 2000 Sunfire

I just discovered that our portable cooler which plugs into the
cigarette lighter of our 2000 Pontiac Sunfire causes problems with the
keyless entry system. With the cooler unplugged I can command the
system from over 20' away but with the cooler plugged in I have to be
right at the drivers side of the windshield and then press the FOB
repeatedly. Thought this might help somebody else.
Mike