Winter is slowly coming. Here on the East Coast, we’re starting to see a gradual cool down as Summer turns to Fall. We’re probably near our last week of 80 degree weather if we’re not seeing it already. That means we need to talk about shutting down the AC. In most cases, you can’t run the air conditioning through a North Eastern winter. Cold weather can, and will destroy your central air, split system, rooftop and window units.
The Water Problem
The air conditioners we have today have a dangerous relationship with water. Back in the early 1900s, air conditioners started out as enormous, expensive dehumidifiers. The fact that these machines cooled the air was just a side effect until people started to like the idea of comfortable work places. This means that air conditioners collect water. Water vapor in the atmosphere will condense on anything cold, such as the evaporator coil in the home or the tubing connecting indoor and outdoor components together.
This isn’t normally much of an issue. In fact, during the summer it’s a good thing. The water collecting on the system helps it to better conduct heat and ultimately operates more efficiently. During the winter however, things become more problematic. Between the cold air and the cold AC, all that condensed water is going to freeze somewhere along the line. It becomes an issue of keeping the air conditioner warm with the air from your home or office.
When the air conditioner gets too cold, the water freezes and begins to interfere. The devil is that water expands when it freezes. It doesn’t go through a thickening, jelly-like state, it pushes out against everything around it. This expansion can damage anything. It can tear a coil apart by forming between the fins and expanding until there’s nothing left intact. Ice can form between motors and their connected fans and blower wheels, eventually forcing it to stop. The amps in the motor will increase, trying to spin the fan, and something’s going to give. Either the motor burns out, the fan snaps apart, or the ice breaks. Chances are the ice won’t break.
The Temperature Problem
The cold temperatures are also, ironically, a problem for the system at large. While air conditioners exist to cool things down, they can’t function well in cold environments. This comes down to a couple of issues. First is that the compressor oil is too ‘heavy’ for winter usage. It’s intended for hot weather and won’t flow or lubricate properly in cold weather. There are oils that work in cold weather, but most end-users won’t benefit from doing oil changes on their compressors. Second is all the added wear and tear to every seal and gasket. Temperature changes cause stress to metals and seals as they expand and contract. Operation in cold weather pushes these stresses to the limit and will eventually start to wear through the weaker gaskets. Lastly, it’s just more wear and tear than you want to put on an expensive system. If you can extend the life of a $5,000+ part of your home or office by opening a window, why wouldn’t you?
When to Shutdown?
This is going to vary by manufacturer, so read the manual and warning labels that came with your system. Our guidance goes: Shut it down when it’s cool enough outside to open a window and be comfortable, and always shut it down before it gets as cold as the manufacturer’s minimum operating temperature. That saves you money in operating costs and keeps your maintenance in check.