Today we were scrapping out a old Day&Night that we changed out a few weeks ago and found this mess. We've never worked on this unit, they just wanted it replaced. The compressor has been out for the past three years according to the customer, but they have still been using the heater. It had an undersized return duct. Static on the new unit before adding more return air was about .8, we got it down to just below .5.
Now, let's see why it got as bad as it did.
There's the limit, where are the wires? This isnt the correct switch for this unit. I guess when the original kept tripping they put this one in so they could crank it up higher.
Oh, here they are. There was no rollout switch, but I'd be willing to bet it would've been bypassed too.
Not that it could work if it was hooked up.
This didn't help any. Any guesses why the compressor went out?
All this combined with the restricted duct, this poor unit never had a chance.