Originally recorded June 23, 2016.
My 4-ton Rheem unit with its Copeland Scroll compressor exhibited an interesting issue, and I lost cooling for a short time. There happened to be a power blip. Normally that's not much of a problem. However, these Copelands can sometimes make loud startup sounds, yet others do not. They can also make a shutdown sound. Yet others do not. If they make a shutdown sound, it is because the pressure in the system spins the scroll backwards for a moment when power is lost.
Now, if power happens to be reapplied at the moment the scroll is going backwards, the compressor will start running in REVERSE, and as such, the air expelled outside is cold and the air inside is warm.
That's exactly what happened. Power was lost, the scroll spun backwards, and while that was happening, power was reapplied, resulting in a backwards-running compressor. There are lockout devices available to prevent this sort of thing from happening. This is the first it ever happened (that I'm aware of) in 10 years, so I expect it's a pretty rare occurrence.
Should the compressor be left to run in reverse, no damage will occur, however the head pressure will get very high until the compressor cannot spin anymore. At that point it will thermal overload out. Upon restart, it will resume operation in the normal direction.
19 авг 2024