I’m gonna keep it simple, but we’re going to get a little technical. If you haven’t already please check out part 1, where we give you a quick rundown of basic components and where to find them on your system. We are going to talk about a few more in this one to help explain how it all comes together, lets dig in.
Electrical
In your system you have the high side (120 vac and 240 vac) and the low side 24 vac. All you really need to remember is that low voltage is for controlling the system and the high side powers the large components. We are gonna start low.
low voltage
So…your house is getting warm and you decide to turn on the a/c. Well, first your thermostat will sense that the temp around it is higher than your setpoint causing it to send 24 volts to your air handler and condenser. The low voltage triggers your blower relay(think of it like a light switch, but instead of flipping it on, its triggered by electricity) allowing your blower motor to receive high voltage and power on. A similar thing happens outside but instead of a relay we have a contactor(though they do essentially the same thing). Low volts trigger the contactor allowing the compressor and condenser fan motor to receive high voltage. And with that all major components are running.
High Side
Fortunately the high side looks very similar for all three major components. After the relay/contactor is triggered it allows the blower, condenser fan motor, and compressor to get high voltage which typically also run through a capacitor. Capacitors store and release energy to help these larger components start and run. And that’s it. But, now that everything is running, how does it cause our home to get cool?
Refrigerant
To understand how refrigerant cools, you need to accept that in a closed system an increase in pressure will cause an increase in temperature and a decrease in pressure causes a decrease in temperature. And that a change of state(such as boiling water into water vaper) requires way more energy than changing the temperature.
So, lets start at the compressor. As the compressor is pushing the refrigerant through the system its actually compressing it, causing the pressure to increase. This increase in pressure also increases the temperature above the outside air temp. This high pressure vapor travels through the condenser, which has the outside air being sucked through it by the condenser fan motor. As the air passes through it cools the refrigerant to the point where it changes from a vapor to a liquid which now travels inside.
That liquid refrigerant passes through the metering device which in simplest terms, is a restriction and causes the pressure to drop as the liquid refrigerant flows into the evap. The blower is forcing air from inside your home through the evaporator where the refrigerant picks up enough heat to become a vapor again. From there its back to compressor to do it all again.
Hopefully that wasn’t too much for one article. But having made it this far, congrats. I want to stress that we didn’t cover everything but this should hopefully make talking to one of us that much easier. Thanks for reading.
