Thread: AC in the winter

Does anyone ever test an AC unit in the winter???

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Originally Posted by Rick Winkler

Does anyone ever test an AC unit in the winter???

Rick,
.
If it's above 60 f. check mine with a hydrometer thermometer before running.

I know that is the rule of thumb, but are the dangers are to the compressor?

TREC SOPS AC Inspection at 60 F. - InspectionNews - Home Inspection

We just finished a post discussing this. Check it out.

Thanks Jim, that was very helpful. Would certainly recommend anyone go read it if they need more info.

My wife is testing ours right now! It is 45f outside and she is having a hot flash. I'm wearing a Polartec jacket and I have a ball cap on, but she is happy!

We have a Scroll compressor and they can safely operate at just about any temperature.

My wife is testing ours right now! It is 45f outside and she is having a hot flash. I'm wearing a Polartec jacket and I have a ball cap on, but she is happy!

Get used to it, after 31 years of marriage, I can attest to the validity of the saying "if momma ain't happy, ain't nobody happy!"

It is ok to test a scroll compressor below 60*F. If you are positively sure that it is a scroll compressor.
Older type compressors have reeds or "valves" in them. When a compressor is idle in cold weather, the refrigerant in the crankcase is in a liquid state. If the compressor is started damage can occur to the valves because they will try to compress liquid instead of gas. Unless you are sure that a compressor has a crankcase heater, never try to start one below 60*F.

Not sure what a scroll compressor is. Sounds like a brand but also sounds like a mechanical process. Also not sure about knowing if I can tell if it has a heater. Obviouusly the weakest part of my knowledge.

Thanks Michael

Originally Posted by Rick Winkler

Not sure what a scroll compressor is. Sounds like a brand but also sounds like a mechanical process. Also not sure about knowing if I can tell if it has a heater. Obviouusly the weakest part of my knowledge.

Thanks Michael

Rick,

Michael is a licensed heating and air professional and licensed Home Inspector.

A scroll compressor is a type of compressor used in many brands of AC condensers.

Until you become familiar with this system,( best not to function test any AC below 60 f.)

Scroll compressors are tall and thin when compared to a conventional piston type compressor.

If you look inside the condenser unit and you see a compressor that is about 2' tall you have a Scroll compressor in it.

The Breakthrough of the Scroll Compressor

October 15, 2007




The first Copeland Scroll® rolled off the production line in 1987, and the cooling industry was changed in a way that would benefit contractors and their customers in many, many ways. The prime benefits have been efficiency and product reliability.

Many features of the Scroll focus on preventing compressor failures, but the Scroll’s primary design also improves efficiency and reliability thanks to its classic, concentric compression scroll, in which one spiral-shaped part fits into another; the space between the two parts contains crescent-shaped gas pockets.


CLASSIC SCROLL OPERATION

In operation, one Scroll is fixed in place while the other orbits within the first. The refrigerant gas is drawn in by the movement and forced toward the center of the scroll through successively smaller pockets, thereby increasing the gas pressure until it reaches its maximum pressure. Then it’s released through a discharge port in the fixed scroll.

Copeland Scroll compressors are unique in the industry because they feature both axial and radial compliance in their design, whereas other scroll models utilize a mechanically fixed design and scroll tip seals.

Axial compliance refers to the ability of the scrolls to separate in the axial — or vertical — direction remaining in continuous contact around an axis, in all normal operating conditions, ensuring minimal leakage without the use of tip seals. Radial compliance refers to the ability of the scroll flanks to separate. These features of the Scroll design allow the compressor to be more tolerant of liquid refrigerant or debris than other technologies, making for a compressor that is extremely durable and reliable.

The combination of axial and radial compliance means that Scroll compressors actually “wear in” rather than wearing out. Continuous flank contact, maintained by centrifugal force, also minimizes gas leakage and maximizes efficiency of the compressor.
Look here for a picture on page 4. On page 65 is a diagram with a description of the compression cycle.
http://www.descoenergy.com/pdf/All%20About%20Scroll%20Compressors%20Copeland.pdf

Jim.

Thank you for that link, while we (non-HVAC techs) need to just skip over the bulk of the 'charts and listings', the other few pages have an excellent description of the scroll compressor and its process of working.

Thanks,