AC terms

Every part, in plain English.

If somebody used a word on you and you nodded, it is probably on this page. What each part does, how it fails, and what it costs to put right.

Accumulator

A tank that catches liquid before it can reach the compressor. A last line of defence, not a fix.

Also: suction accumulator

Air handler

The indoor box. Blower, coil, filter, drain pan, and most of the water problems.

Also: indoor unit

Blower motor

The indoor motor. If no air is coming out of the vents, start here.

Also: indoor fan motor

BTU

The unit heat is measured in. Everything else about capacity is arithmetic on top of it.

Also: British Thermal Unit

Capacitor

A metal can that starts the motors. The most common summer failure in the Valley, and one of the cheapest.

Also: run capacitor

Compressor

The pump in the outdoor unit. The expensive one, and the reason the cheap faults are worth catching early.

Also: the pump

Condensate pump

A small pump that lifts drain water uphill. When it quits, the pan fills.

Also: condensate lift pump

Condenser

The outdoor unit. Its whole job is throwing your house's heat into the air, which gets harder at 115.

Also: outdoor unit

Condenser coil

The fins on the outside of the outdoor unit. In the Valley this is the part that quietly costs you money.

Also: outdoor coil

Condenser fan motor

The fan on top of the outdoor unit. When it stops, the system cooks itself within minutes.

Also: outdoor fan motor

Contactor

The relay that switches the outdoor unit on. Cheap, mechanical, and it wears out.

Also: relay

Control board

The brain. Often blamed, less often guilty, and the fault light on it is free information.

Also: circuit board

Crankcase heater

A small heater keeping refrigerant out of the compressor oil. The reason not to kill the breaker all winter.

Also: compressor heater

Damper

Plates inside the duct that decide where the air goes. A stuck one starves a whole zone.

Also: zone damper

Defrost cycle

Winter frost on a heat pump is normal. The steam and the noise are the system clearing it.

Also: defrost board

Delta T

The difference between the air going in and the air coming out. The quickest honest read on whether a system is working.

Also: temperature split

Disconnect

The small box on the wall beside the outdoor unit. It cuts power to the condenser, and it is not a thermostat.

Also: pull-out

Drain pan

The tray catching everything the coil condenses. The first place to look when a system dies for no reason.

Also: condensate pan

Ductwork

The part of the system nobody looks at, running through the hottest place in the house.

Also: ducts

EER

Efficiency measured at one hot temperature. For this city, more honest than the seasonal number.

Also: EER2

Emergency heat

A heat pump setting that bypasses the heat pump. Expensive, and almost never what you want on by accident.

Also: EM heat

Evaporative cooler

A fan, a pump and wet pads. Brilliant in May, useless in August, and still on plenty of Valley roofs.

Also: swamp cooler

Evaporator coil

The indoor coil. Where the cold is made and where the water comes from.

Also: indoor coil

Filter drier

A cylinder on the liquid line catching moisture and debris. Replaced every time the system is opened, or it should be.

Also: liquid line drier

Filter size

Three numbers on the cardboard edge. Getting them right matters more than the MERV number does.

Also: 16x25x1

Float switch

The safety that shuts the system down before water reaches your ceiling. Often the reason a working AC suddenly stops.

Also: safety switch

Hard start kit

A booster for a compressor that struggles to start. Sometimes the right call, often a way of not fixing the real problem.

Also: start assist

Heat pump

Two kinds of outdoor unit. Which one you have changes what can fail and what the fix is.

Also: reverse cycle

High pressure switch

A safety that stops the compressor before something gives. When it trips, it is reporting, not failing.

Also: high limit

Inverter

A compressor that can run at part speed instead of all or nothing. Better comfort, more expensive electronics.

Also: variable speed

Latent and sensible heat

Two kinds of work an AC does. The thermostat only measures one of them.

Also: sensible cooling

Line set

The two copper pipes between inside and outside. Which one is sweating tells you something.

Also: refrigerant lines

Low pressure switch

A safety that stops the compressor when suction pressure falls too far. Usually reporting a leak.

Also: loss of charge switch

MERV rating

The number on the filter. Higher is not automatically better, and in the Valley it can cost you a coil.

Also: filter rating

Mini split

Refrigerant to the room instead of air through ducts. Useful for the room central air cannot reach.

Also: ductless

Package unit

Everything in one cabinet, usually on the roof. Common on Valley ranch houses, and a different job to work on.

Also: rooftop unit

Plenum

The box where the ducts meet the equipment. A leak here is the most expensive leak in the system.

Also: supply plenum

Refrigerant

The working fluid. A sealed system does not use it up, so if it is low, it leaked.

Also: freon

Return air

Half the system, and the half most Phoenix houses are short on.

Also: return grille

Reversing valve

The part that makes a heat pump a heat pump. Stuck, it can heat your house in July.

Also: four way valve

Schrader valve

The service ports gauges connect to. Small, routinely overlooked, and a common slow leak.

Also: service port

SEER2

The efficiency rating. Useful for comparing equipment, nearly useless for predicting your bill.

Also: SEER

Service valve

Where the line set meets the outdoor unit. Frost here points somewhere specific.

Also: king valve

Static pressure

The blood pressure of the duct system. High readings explain most airflow complaints.

Also: total external static pressure

Subcooling

How far below its boiling point the liquid refrigerant is. The charge measurement on a TXV system.

Also: sub cooling

Superheat

How far above its boiling point the returning gas is. The measurement that keeps liquid out of the compressor.

Also: super heat

Ton

A unit of cooling capacity, named after ice. Bigger is not better, and oversized systems cool badly.

Also: tonnage

Transformer

Makes the 24 volt control power everything else runs on. When it dies, the thermostat goes dark.

Also: control transformer

Two stage

High and low instead of on and off. Most of the comfort benefit of an inverter, less of the electronics.

Also: dual stage

TXV

The valve that decides how much refrigerant reaches the indoor coil. When it misbehaves it looks exactly like a leak.

Also: thermostatic expansion valve

Every price mentioned on these is on the price list, and the guides cover what to do when one of them fails.

Somebody told you a part failed?

Read me what is on the quote. I will tell you what it is and what it should cost.

(602) 935-7471 or text the same number