I have an Coleman combined heat pump and electric furnace. When we use the heat pump for heating in the winter it works well but when using the emergency heat the blower psushes out a bad smell like fish smell,
Can you help identify the problem and solution.

Prob. The a-coil needs fumeagated,, but the smell should also be there when heatpump is used,, have you searched the furnace/airhandler for any dead varmits?