When your heat pump unit begins to smell like dirty socks, there are several remedies you can use to reduce or eliminate this odor. A temporary method is to clean bacteria and mold from your heat pump coils, for it is the molds and bacteria that cause these smells. Another, more long lasting method is to use a protectant.
Using Alathene II Spray to Prevent Dirty Socks Smells
By spraying a coat of Alathene II onto the coils of your heat pump, you can often protect them from a build up of bacteria that are known causes of the bad smells that can emanate from your heat pump.