Mitsubishi Heat Pump Seattle

Marina Lehane
20 days ago

I recently had a ducted system installed using a Mitsubishi MXZ-4C36NA2 with 2 PEAD 18k units in the attic.
When the temperature reached as low as 30F in Seattle recently, my house couldn't get above 56F overnight with the system running 24/7. It turned out the system was stuck in defrost cycles, a technician manual defrosted the system but even now when running at above 30F outside since, it can't get above 60F indoors overnight.
We're currently dealing with large single pane aluminum windows from the 50s until we change them for double pane fiberglass in spring. I know that's leaking heat but concerned the problem will still exist next winter, when we're out of warranty, if I bet on the windows. Do I have the wrong units for my situation?

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