Musty odor on cooling

Old 05-30-23, 06:35 AM
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Musty odor on cooling

System: Trane heat pump, whole house ventilation.
Symptom: Musty odor on cooling only.
Background: Trane heat pump system. Evaporator coil has been replaced two years ago and cleaned professionally two weeks ago.

Background: There is no odor in the heating mode. During shoulder season when I switch from heating to cooling multiple times, the odor is present for about 30 minutes after switching to cooling and then disappears. During the rest of the summer season there is no odor. When the odor is present, it comes out of every vent in the house. Thus, a dead animal in one of the ducts is unlikely; and, besides, a dead animal would smell in both heating and cooling modes.

What has been done: I change the intake filters every 30 days. The unit is professionally serviced every six months. The evaporator coils have been professionally cleaned and I have cleaned them myself and sprayed them with anti-bacterial and anti-fungal spray. Still the problem persists.

Any ideas are very welcome.
Old 06-04-23, 08:08 PM
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Is the air cold ? What is delta T number ?
Old 06-05-23, 12:28 AM
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Condensate pan and drain line clean?

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