We have a Heil heat pump package system in N. FL. Last winter it developed a condition called 'dirty sock' syndrome. We had a professional clean the unit and coat the coil with a white teflon-type paint made for this condition. The remainder of the year the unit did not smell and all summer it was fine with AC. But, as soon as we turned on heat this year, the sock smell was back...BUT, not all the time. It occurs only when the system goes into defrost mode and uses the heat strips.

My question is can the heat strips alone be replaced? Possibly they are old and new strips would stop the stick!

Thanks!

Replacing the heat strips will probably not make a difference since they run at a high temperature and nothing to create odors will be left after they have run for a few minutes. It would burn off.

Dirty sock syndrome can cause quite a stink in the home. I suggest that the duct and the coil in the unit is checked for debris/mold etc again. Also have whoever does the work use a good commercial HVAC cleaning agent and clean all areas at least two times to be sure to get it all.