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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22540
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a honeywell chronotherm IV and an Aprilaire unit.

Customer Question

I have a honeywell chronotherm IV and an Aprilaire unit. Zone 2 is in recovery without any cooling or extremely slow cooling with very weak flow through the vents. It was giving a "filter" alert for the past 3 months but we had just moved in this house and were doing renovations with demolition dust etc. therefore we were waiting for this to finish before servicing the unit. Zone 1 cools well (it also had the filter alert) Zone 2 was working fine until we went on vacation for 2 weeks and the person doing painting in Zone 2 was running the unit very cool. There was also some "whistling" high pitched noise coming from the blower/ coil unit before which cannot be heard now. What might be wrong?
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.


There is 90% chance you are freezing the coil over above the furnace. Once a filter gets restricted it reduces airflow and then freezes coil with frost/ice. During construction it is best to change the filter weekly.