What is an air handler — and how is it different from a furnace?
An air handler is the indoor unit that circulates your conditioned air. It holds the blower motor, the indoor coil, and the air filter, and it pairs with a heat pump or air conditioner to move heat in or out of your home. It's the all-electric counterpart to a furnace: a furnace burns fuel to make heat, while an air handler simply moves air — no combustion, no flue, no gas line.
What is an air handler made of?
Open one up and there are three things that matter. The blower motor and fan are the heart of it — they push conditioned air through your ducts to every room. The evaporator coil is where the refrigerant does its work, cooling or heating the air as it passes, and the air filter sits just ahead of it to keep dust off the coil. Some air handlers also carry electric heat strips — resistance elements that provide backup heat for a heat pump on the coldest days.
The filter that lives here: air filters — how often, which MERV, size.
Air handler vs. furnace — what's the difference?
Both sit indoors and blow air through your ducts, which is why they get confused — but they do fundamentally different jobs. A furnace makes heat by burning gas (or, less often, oil) and needs a gas line and a flue to vent the exhaust. An air handler moves air and makes no heat of its own; it takes its heating and cooling from a heat pump or AC and runs purely on electricity. Your home has one or the other as its indoor unit — an air handler with a heat pump, or a furnace with an AC coil on top.
The systems these pair with: heat pump vs air conditioner. Ductless homes use no central air handler at all — see what is a ductless mini split.
Air handler vs. condenser — which is which?
A central system has two boxes, and it helps to know which does what. The air handler is the indoor unit — the blower and indoor coil, usually tucked in a closet, attic, or basement, and the place you change the filter. The condenser is the outdoor unit on a pad outside, holding the compressor and outdoor coil that trade heat with the outside air (in a heat pump, this unit works in both directions). Refrigerant lines link the two into a single split system.
How do you maintain an air handler, and what goes wrong?
Nearly everything about an air handler comes back to airflow, which is why the single most valuable habit is changing the air filter on schedule — a clogged filter chokes the blower and can freeze the coil. The other common faults are a failing blower motor or capacitor, a frozen indoor coil from low airflow or low refrigerant, and a blocked condensate drain that leaks water near the unit. A frozen coil or a wet floor is worth a professional's look rather than guesswork.
One call routes you to a licensed local contractor to check the blower, coil, and drain: (888) 810-2291.
Common questions
What is an air handler?
An air handler is the indoor unit that circulates your conditioned air. It houses the blower motor and fan, the indoor (evaporator) coil, and the air filter, and it pairs with a heat pump or air conditioner. It moves air rather than making heat by burning fuel.
What is the difference between an air handler and a furnace?
Both are the indoor blower unit, but a furnace burns fuel to create heat, while an air handler only moves air and gets its heating and cooling from a heat pump or AC. A furnace needs a gas line and a flue; an air handler runs on electricity with neither.
Do I have an air handler or a furnace?
Look at how your home is heated. If you have a gas line and a flue or vent pipe on the indoor unit, it's a furnace. If the indoor unit runs on electricity and pairs with a heat pump outside — no gas, no flue — it's an air handler. All-electric and heat-pump homes have air handlers.
What is the difference between an air handler and a condenser?
The air handler is the indoor unit; the condenser (or heat pump) is the outdoor unit. The air handler holds the blower and indoor coil and feeds your ducts, while the condenser holds the compressor and outdoor coil. Refrigerant lines connect the two into one split system.
Does an air handler heat the home?
On its own, only if it has electric heat strips fitted for backup. Its main heating comes from the heat pump it's paired with, which moves heat indoors; the air handler's blower then distributes that warm air through the ducts. In cooling mode it distributes the cool air the same way.
Where is the air handler located and where is its filter?
Air handlers are usually installed indoors out of the way — a closet, the attic, the basement, or a garage. The air filter sits at the return where air enters the unit, so the air handler is typically where you change it. A clean filter is what keeps its blower healthy.
What are common air handler problems?
The most common are a clogged air filter choking airflow, a failing blower motor or capacitor, a frozen indoor coil from low airflow or low refrigerant, and a blocked condensate drain that leaks water. Most trace back to airflow, which is why filter changes matter so much.