My furnace clicks but never lights. What should I check?

Confirm the thermostat is set to heat and above room temperature, the filter is not clogged, and the furnace breaker or switch is on (reset once, never repeatedly). If it still will not light, stop there. The likely causes are an igniter, a flame sensor or a pressure switch, and all of them live behind panels that should stay closed. The heating repair page covers what happens next.

Is a 96 percent furnace worth it in Phoenix?

Rarely on fuel savings alone. The heating season is too short for the efficiency gap to pay back the extra equipment and venting cost quickly. It can still make sense if the venting is easy, if incentives apply, or if you want the variable-speed blower that usually comes with it for summer comfort. We will say so either way after seeing the house.

I smell something burning the first time I run heat each year. Is that normal?

A brief dusty smell on the first fire of the season is common: it is summer dust burning off the heat exchanger and burners, and it should clear within an hour. A persistent smell, a metallic or electrical smell, or any carbon monoxide alarm is not normal. Shut the furnace off and call.

Why does my furnace affect my air conditioning?

Because the furnace blower moves the air for both. A weak blower motor, a failing capacitor or a dirty blower wheel reduces summer airflow, which shows up as poor cooling or a frozen coil. Replacing an outdoor unit without addressing an aging furnace often leaves that limit in place. The bad airflow page covers the symptoms.

Should I replace my furnace when I replace my AC?

If the furnace is past twelve to fifteen years, usually yes: the blower is shared, the coil sits on top of it, and doing both at once avoids paying for the labor twice. If the furnace is much newer than the AC, keeping it is reasonable, provided the blower can deliver the airflow the new system needs. That is a measurement, not a guess.

How often does the heat exchanger need inspection?

Every year, as part of the fall tune-up. Cracks are not visible from outside the cabinet and do not announce themselves with symptoms until they are serious. Furnaces past fifteen years and horizontal attic units deserve extra scrutiny. Keep working CO alarms regardless.

Does a furnace replacement need a permit in the Valley?

Generally, yes. Furnace replacements involve gas and venting, and Valley municipalities typically require a mechanical permit and inspection. A licensed, bonded and insured contractor pulls it as part of the job. If a quote does not include one, ask why.

My furnace clicks but never lights. What should I check?

Confirm the thermostat is set to heat and above room temperature, the filter is not clogged, and the furnace breaker or switch is on (reset once, never repeatedly). If it still will not light, stop there. The likely causes are an igniter, a flame sensor or a pressure switch, and all of them live behind panels that should stay closed. The heating repair page covers what happens next.

Is a 96 percent furnace worth it in Phoenix?

Rarely on fuel savings alone. The heating season is too short for the efficiency gap to pay back the extra equipment and venting cost quickly. It can still make sense if the venting is easy, if incentives apply, or if you want the variable-speed blower that usually comes with it for summer comfort. We will say so either way after seeing the house.

I smell something burning the first time I run heat each year. Is that normal?

A brief dusty smell on the first fire of the season is common: it is summer dust burning off the heat exchanger and burners, and it should clear within an hour. A persistent smell, a metallic or electrical smell, or any carbon monoxide alarm is not normal. Shut the furnace off and call.

Why does my furnace affect my air conditioning?

Because the furnace blower moves the air for both. A weak blower motor, a failing capacitor or a dirty blower wheel reduces summer airflow, which shows up as poor cooling or a frozen coil. Replacing an outdoor unit without addressing an aging furnace often leaves that limit in place. The bad airflow page covers the symptoms.

Should I replace my furnace when I replace my AC?

If the furnace is past twelve to fifteen years, usually yes: the blower is shared, the coil sits on top of it, and doing both at once avoids paying for the labor twice. If the furnace is much newer than the AC, keeping it is reasonable, provided the blower can deliver the airflow the new system needs. That is a measurement, not a guess.

How often does the heat exchanger need inspection?

Every year, as part of the fall tune-up. Cracks are not visible from outside the cabinet and do not announce themselves with symptoms until they are serious. Furnaces past fifteen years and horizontal attic units deserve extra scrutiny. Keep working CO alarms regardless.

Does a furnace replacement need a permit in the Valley?

Generally, yes. Furnace replacements involve gas and venting, and Valley municipalities typically require a mechanical permit and inspection. A licensed, bonded and insured contractor pulls it as part of the job. If a quote does not include one, ask why.

Gas Furnaces and Air Handlers in Phoenix Homes

Gas Furnaces and Air Handlers

In a Phoenix split system the furnace is the blower for your air conditioner eleven months of the year and a heater for the twelfth. Both jobs deserve attention.

The furnace is your AC's blower, too

AFUE matters less in a short winter

Igniters fail after long idle summers

Combustion and CO check every fall

Schedule today — we’re here 24/7.

Veteran Owned & Operated

What a furnace actually does

A gas furnace is four things: a gas valve, a burner assembly, a heat exchanger and a blower. The thermostat calls. A small inducer fan starts first, proving the flue can draw, and a pressure switch confirms it. The igniter glows or sparks, the gas valve opens, the burners light, and a flame sensor verifies within seconds that they did. If it sees no flame, the valve shuts. Combustion gases travel through the heat exchanger, a sealed set of metal passages, and out the flue. Then the blower starts and pushes house air across its outside surface. The air warms; the exhaust never touches it. That separation is the entire safety premise of a furnace, and it is the thing an annual inspection exists to verify. A condensing furnace adds a second exchanger that wrings more heat out of the exhaust, cool enough to vent through plastic pipe.

The furnace is also your air conditioner

In a gas-heated Phoenix home, the furnace cabinet holds the blower for the whole system. The evaporator coil sits in a box on top of it. Every summer hour your AC runs, the furnace blower is running. A furnace in the Valley works harder in July than in January, and a failing blower motor announces itself as a cooling problem. Furnace age also matters when you replace the outdoor unit: a new condenser pushing through a fifteen-year-old blower is a mismatched system. An all-electric home skips the furnace entirely and uses an air handler, which is the same blower and coil in a cabinet with optional electric strips. The air handler page covers that version.

AFUE, staging and what they are worth here

AFUE

Annual Fuel Utilization Efficiency is the share of gas that becomes heat in the house. An 80 percent furnace sends a fifth of its fuel up the flue; a condensing furnace in the mid-90s sends a few percent. In Phoenix, where the heating season is a few weeks of mornings, the savings are real but small, and the added cost of venting and condensate handling does not always pay back. It is one of the few places in HVAC where the cheaper option is often the honest recommendation.

Single-stage, two-stage and modulating

A single-stage furnace is on or off at full fire. A two-stage runs low most of the time and high when needed. A modulating furnace adjusts its flame in small increments and pairs with a variable-speed blower. In the Valley, the comfort benefit of staging shows up more in the blower than the burner: a variable-speed blower runs quieter, moves air more evenly and helps the air conditioner it serves all summer. If you are choosing between a better burner and a better blower for a Phoenix home, choose the blower. The staging guide explains the tiers across both seasons.

Where you find it in Phoenix homes

Gas furnaces cluster where gas lines run: older central Phoenix, Tempe, Scottsdale, much of Mesa and Chandler. In a single-story ranch the furnace is usually in a hall closet, a laundry room or a garage alcove. In two-story homes and most newer builds it lies horizontal on a platform in the attic, breathing 155-degree air all summer and sharing the space with the ducts. Attic furnaces are harder to service and harder on the equipment; a closet unit is the lucky draw. Homes with a single rooftop cabinet have a packaged gas-electric unit, which is a furnace and an AC in one box; the rooftop unit page covers those.

What typically fails and when

Phoenix furnaces fail in a specific way: they sit idle for eight or nine months, then get asked to light on the first cold morning in November.

Igniters, years four to eight. Hot-surface igniters are brittle ceramic. They crack from thermal cycling and, after a summer of dust settling on them, often fail on the first call of the season.
Flame sensors, any age. A thin rod that oxidizes over an idle summer. The burners light, run for a few seconds and shut off. A cleaning fixes it more often than a part does.
Pressure switches and inducer motors, years eight and up. Dust, plus a monsoon's worth of humidity in the flue. The furnace refuses to start the ignition sequence at all.
Blower motors and capacitors, any age. These fail in summer, from cooling duty, and show up as an AC problem.
Heat exchangers, years fifteen and beyond. Cracks from decades of expansion and contraction. This is the failure that matters, because it can let combustion gases into the air stream.

The combustion and CO check is not optional

Every fall, before the first cold morning, a furnace should be inspected with instruments: combustion analysis at the flue, a carbon monoxide reading in the supply air, a visual and camera inspection of the heat exchanger, and a check of the venting. This is not a sales opportunity. It is the one procedure that stands between a cracked exchanger and a family breathing its exhaust. A working carbon monoxide alarm on each level of the house is the second line, not the first. If a technician recommends replacing a furnace for a cracked exchanger, ask to see the evidence. The heating maintenance page describes the full fall inspection.

When to repair and when to stop

Most furnace repairs in the Valley are small: an igniter, a sensor, a switch. A furnace under fifteen years with a sound exchanger is almost always worth fixing. Past that, or with a cracked exchanger at any age, the calculation changes. The repair-or-replace guide lays out the reasoning, and financing on approved credit is available when replacement is the answer. Either way, this page cannot inspect your heat exchanger or size a replacement. That takes a technician in front of the equipment, an on-site evaluation, and a flat-rate price quoted before anything is touched.

Gas Furnaces and Air Handlers

In a Phoenix split system the furnace is the blower for your air conditioner eleven months of the year and a heater for the twelfth. Both jobs deserve attention.

The furnace is your AC's blower, too

AFUE matters less in a short winter

Igniters fail after long idle summers

Combustion and CO check every fall

Schedule today — we’re here 24/7.

Veteran Owned & Operated

What typically fails and when

Igniters, years four to eight. Hot-surface igniters are brittle ceramic. They crack from thermal cycling and, after a summer of dust settling on them, often fail on the first call of the season.

Flame sensors, any age. A thin rod that oxidizes over an idle summer. The burners light, run for a few seconds and shut off. A cleaning fixes it more often than a part does.

Pressure switches and inducer motors, years eight and up. Dust, plus a monsoon's worth of humidity in the flue. The furnace refuses to start the ignition sequence at all.

Blower motors and capacitors, any age. These fail in summer, from cooling duty, and show up as an AC problem.

Heat exchangers, years fifteen and beyond. Cracks from decades of expansion and contraction. This is the failure that matters, because it can let combustion gases into the air stream.

Air Conditioning

Heating & Furnace

Ductwork & Airflow

Commercial HVAC

Phoenix HVAC Hub

About Bleuwave

Gas Furnaces and Air Handlers

What a furnace actually does

The furnace is also your air conditioner

AFUE, staging and what they are worth here

AFUE

Single-stage, two-stage and modulating

Where you find it in Phoenix homes

What typically fails and when

The combustion and CO check is not optional

When to repair and when to stop

Current offers

Gas Furnaces and Air Handlers: common questions

Keep reading

Gas Furnace Service throughout the Phoenix area

Light it once a year with someone watching

Request service

Gas Furnaces and Air Handlers

What a furnace actually does

The furnace is also your air conditioner

AFUE, staging and what they are worth here

AFUE

Single-stage, two-stage and modulating

Where you find it in Phoenix homes

What typically fails and when

The combustion and CO check is not optional

When to repair and when to stop

Current offers

Gas Furnaces and Air Handlers: common questions

Keep reading

Gas Furnace Service throughout the Phoenix area

Light it once a year with someone watching

Request service