What fun questions can I ask a heating and AC technician?

Outside! Inside your house there is a cold coil. A special fluid called refrigerant runs through it and soaks up heat from the air. Then it travels through pipes to the outside unit, and a big fan blows the heat out into the yard.

The coil inside is very cold. When warm, damp air touches it, the water floating in the air turns into drops, just like drops on a cold glass of lemonade. That is called condensation. The water drips into a pan and flows out through a drain pipe.

On a working system, the air coming out of a vent is usually about 15 to 20 degrees cooler than the air going in. Techs check this with a thermometer.

Many outside units blow the hot air up and away. Warm air rises anyway, so blowing it upward helps get the heat away from the unit so it does not just suck it back in.

Long ago, people cooled buildings with big blocks of ice. A “ton” of cooling means about as much cooling as melting a ton of ice over a whole day. Techs still use that word to say how big an AC is.

The fat pipe carries refrigerant as a cool gas back to the outside unit. It is wrapped in foam to keep it cold. The skinny pipe carries refrigerant as a liquid back inside.

It is not supposed to! If air cannot move across the cold coil, for example because of a very dirty filter or a blocked return grille, the coil can get so cold that ice forms on it. If you ever see ice on pipes or the machine, tell a grown-up.

A heat pump is an AC that can also run backwards. In winter it pulls heat from the outside air, even cool air has some, and moves it into your house. Lots of Austin homes have them.

On cold, damp days, frost can build up on a heat pump’s outside coil. Every so often it warms the coil to melt the frost. The melting frost can make a cloud of steam.

Inside the thermostat is a tiny sensor, a part that changes when it gets warmer or cooler. The thermostat reads that change like a thermometer and decides when to turn the system on.

Every tech has a favorite! Many say their gauges, which show how the refrigerant is moving, or their meter, which measures electricity. Some say their flashlight, because you cannot fix what you cannot see.

Many techs take classes at a trade school or community college, then work alongside an experienced tech to learn on real jobs. To work with refrigerant, techs must pass a certification test. Texas also has state rules and licenses for AC work.

For most Austin techs, the answer is an attic in summer. Attics can get much hotter than the outdoors because the sun bakes the roof all day. Techs drink lots of water, take breaks and wear special gear.

Techs find toys, socks and papers pulled up against the big return grille, and leaves and twigs inside outside units. Ask your tech for their strangest find!

To keep your floors clean. Techs walk through yards, garages and attics all day, and the booties keep that dust and dirt off your carpet.

Copper is very good at letting heat pass through it. Scientists call that a good conductor. It also bends without breaking, so techs can shape it to fit.

The fins give the coil lots more surface, so more air touches more metal. More touching means heat moves faster. They are thin and bend easily.

The filter catches dust, fur and lint before they get to the machine. That keeps the coil and fan clean so air can flow through easily.

An engineer named Willis Carrier is known for building one of the first modern air conditioners in 1902. It was for a printing company, to control how damp the air was so the paper would not wrinkle.

On a hot day, more heat sneaks into your house through the roof, walls and windows. The AC has to move all that heat back outside, so it runs longer. That is normal.