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December 8, 2025

Phoenix HVAC: Why Your Heating System Won’t Work — Fixes

Estimated Read Time: 9 minutes

Heater not working on a chilly Arizona morning? You are not alone. From simple thermostat settings to ignition issues, many problems have quick fixes you can try before calling a pro. In this guide, you will learn the five most common causes and what to do next. If you need help now, call Emergency Air Heating and Cooling at (602) 894-9228 for 24/7 service and current coupons.

Safety First: What To Do Before Troubleshooting

Before you touch the heater, keep safety at the top of your checklist.

  1. Turn off power at the switch or breaker if you smell gas or see sparks.
  2. For gas furnaces, if you smell gas, leave the house and call your utility or 911.
  3. Give electric heat pumps and furnaces 5 minutes after power cycling to reset.
  4. Keep children and pets away from panels and burners.

Arizona tip: Dust and construction debris are common in Phoenix and the East Valley. That buildup affects filters, flames, and sensors. A quick visual check for dust mats around return grills can save time.

Reason 1: Thermostat or App Settings Are Off

Thermostats cause more no‑heat calls than any other part.

  1. Confirm the mode is set to Heat, not Cool or Off.
  2. Set the temperature 3 to 5 degrees above room temp.
  3. Check the schedule. Temporary holds often expire at night.
  4. Replace batteries. Many wall thermostats go dead silently.
  5. For smart stats, confirm Wi‑Fi and location. Wrong time zones or Eco modes may delay heat.

How to fix it

  • Replace batteries and restart the thermostat.
  • Bypass schedules by selecting Hold and setting your desired heat.
  • If you recently installed a new smart thermostat, verify it matches your system type. Heat pumps with or without auxiliary heat require the correct wiring and configuration.

When to call a pro

  • If your thermostat screen is blank after battery changes, or the system short cycles, there may be a low‑voltage wiring or control board issue.

Reason 2: Tripped Breaker or Furnace Switch

A tripped breaker or disabled switch stops the entire system. It is easy to miss.

What to check

  1. Furnace switch. Look for a standard light switch on or near the furnace or air handler. It should be On.
  2. Service panel. Check for tripped breakers labeled Furnace, Air Handler, or Heat Pump. Fully switch Off, then back On.
  3. Outdoor unit. Heat pumps have a separate breaker and a pull‑out disconnect.

How to fix it

  • Reset the breaker once. If it trips again, do not keep flipping it. That points to a shorted motor or control.
  • Inspect the door switch. An open blower door keeps many furnaces from starting.

When to call a pro

  • Repeated trips signal failing capacitors, seized blower motors, or shorted wiring. A licensed technician can test amperage draw and insulation resistance and replace parts safely.

Reason 3: Dirty Filter or Blocked Airflow

Restricted airflow is a top reason a heater is not working well or is shutting off.

What happens

  • Furnaces overheat and trip a safety limit when airflow is low.
  • Heat pumps struggle to move enough air across the coil, so rooms feel cool.

What to check

  1. Filter. If you cannot see light through it, replace it. In dusty Phoenix neighborhoods, monthly checks are smart.
  2. Return grills. Remove pet hair mats and vacuum lint.
  3. Supply vents. Open at least 80 percent of vents to prevent pressure buildup.

How to fix it

  • Use the right filter size and MERV rating. MERV 8 to 11 is usually safe for most homes without choking airflow.
  • After replacing the filter, power cycle the system to clear lockouts.

When to call a pro

  • If the furnace keeps shutting down, you may have a bad limit switch, clogged evaporator coil, or duct issues. A 20‑point inspection will locate the restriction.

Reason 4: Ignition or Pilot Problems

If your gas furnace clicks but does not fire, the ignition system may be the culprit.

Common causes

  • Dirty flame sensor that fails to prove flame.
  • Faulty hot surface igniter or spark igniter.
  • Closed gas valve or tripped gas shutoff.
  • For older units, a pilot that will not stay lit due to a bad thermocouple.

How to fix it

  1. Verify the furnace gas valve is On and the manual gas cock is parallel to the pipe.
  2. Reset the furnace power. Some ignition boards will clear a soft lockout.
  3. Do not sand flame sensors with heavy grit. A light, careful cleaning by a pro is better to avoid damage.

When to call a pro

  • Ignition parts are delicate and sit near open flame. A licensed tech can test microamp readings on the flame sensor, ohm the igniter, and verify safe combustion. If your furnace fails to ignite three times in a row, call for service.

Reason 5: Blower Motor, Capacitor, or Limit Switch

When the thermostat calls for heat but there is no air from the vents, focus on the blower assembly and safeties.

Symptoms

  • Furnace lights, then shuts down quickly. The fan never starts.
  • Heat pump runs outside, but the indoor fan is silent.
  • Intermittent heat followed by a burning smell. The motor may be overheating.

How to fix it

  • Listen for a quiet hum. That often means a failed capacitor on PSC motors.
  • Check for a full dust cake on the blower wheel. Heavy buildup unbalances the wheel and reduces airflow.
  • If you recently had a filter collapse, debris may have hit the blower or coil.

When to call a pro

  • Motors, ECM modules, and limit switches require testing under load. Replacing the wrong part wastes money and time. Our fully stocked trucks can usually replace a failed motor or capacitor same day.

Heat Pumps Acting Like They Are Not Heating

In the Valley, many homes use heat pumps. They feel different from gas heat.

Normal heat pump behavior

  • Air feels warm but not hot. Supply air is often 90 to 100 degrees.
  • Defrost cycle. On cold mornings, the outdoor unit can steam and pause while reversing to melt frost. That is normal.

What to try

  1. Increase the setpoint slightly and give it 10 to 15 minutes.
  2. Ensure the outdoor coil is clear of leaves and dust.
  3. If your auxiliary heat strips do not come on, you may have a breaker off or a failed relay.

When to call a pro

  • If your bill spiked and the system runs nonstop, schedule a performance check. Improper refrigerant charge or a failing reversing valve can mimic thermostat issues.

When To Repair vs Replace

No one wants a surprise replacement, but sometimes it saves money.

Repair makes sense when

  • The system is under 10 years old and has a single failed part.
  • Your heat exchanger and compressor test healthy.
  • Ductwork is in good shape and your comfort is decent.

Consider replacement when

  1. Repairs exceed 30 percent of the cost of a new system.
  2. The heat exchanger is cracked or the compressor is failing.
  3. Your system is 15 to 20 years old and uses outdated technology.
  4. Your home has uneven rooms that could benefit from zoning or a modern variable‑speed system.

Local advantages

  • As a Carrier Factory Authorized Dealer, we can access factory rebates and offer financing for up to 60 months with approved credit. That helps spread out the cost while lowering monthly energy bills.

What Our 20‑Point Heating Inspection Covers

A thorough tune‑up restores performance and prevents surprise breakdowns.

Highlights of our inspection

  1. Thermostat calibration and cycle test.
  2. Electrical testing, capacitors, contactors, and wiring.
  3. Combustion analysis and flame sensor microamps where applicable.
  4. Heat exchanger and draft operation check.
  5. Blower wheel cleaning assessment and amp draw.
  6. Filter, return, and supply airflow checks.
  7. Safety limit, pressure switch, and inducer operation.
  8. For heat pumps, refrigerant performance, defrost control, and outdoor coil condition.

You also receive upfront pricing for any needed repairs, before and after photos on request, and priority scheduling as part of our maintenance agreement.

Arizona‑Specific Tips To Keep Heat Reliable

  • Dust storms and monsoon debris clog outdoor coils. Hose the outdoor coil gently from the inside out every spring.
  • In Ahwatukee, Chandler, and Gilbert, attic air handlers run hot. Insulate attic hatches and consider a media filter cabinet to reduce attic filter changes.
  • Pets and tile floors common in Phoenix homes kick up fine dust. Check filters monthly in winter and every two weeks during remodels.

Simple Homeowner Fix List

  1. Replace thermostat batteries and set Heat mode.
  2. Check the furnace switch and reset a tripped breaker once.
  3. Replace a dirty filter and open closed vents.
  4. Confirm the gas valve is On for gas furnaces.
  5. Clear leaves and dust from the outdoor heat pump coil.

If these do not restore heat, schedule service. Most no‑heat calls are resolved the same day with a proper diagnosis.

Why Choose Emergency Air Heating and Cooling

  • 24/7 emergency response with trucks stocked with factory‑authorized parts for same‑day fixes.
  • A+ BBB rating and BBB Ethics Award, plus Angi Super Service Award.
  • Carrier Presidents Award for four consecutive years and repair‑first philosophy to save you money.
  • Upfront pricing with no overtime fees and a 100 percent satisfaction guarantee.

Service Area

We serve Phoenix, Mesa, Chandler, Gilbert, Scottsdale, Glendale, Peoria, Tempe, Surprise, and Goodyear. If your heater is not working in any of these cities, we can help today.

Special Offers for Heating Service

  • Save $59 on a Furnace Tune‑Up. Call (602) 894-9228 and mention the $59 tune‑up.
  • Free Furnace Diagnostic Waived With Repairs. Call for details.
  • Free Second Opinions on Replacement Systems. Get peace of mind before you decide.

Act now to secure priority scheduling. Visit https://www.emergencyair.com/ or call (602) 894-9228.

What Homeowners Are Saying

"By 11:00 AM Lorenzo was here, quickly assessed that a wire was not attached to the gas valve, and we had heat. He even cleaned up the mess left by the installing company. He went over the maintenance plan with us and got us set up. Lorenzo and Emergency Air and Heating are top notch!"
–Bev R., Heating Repair
"This job was a complete conversation from a gas furnace, out door condenser system to a heat pump system! The install crew was incredible! ... They were so professional, always available to answer questions!"
–Kenneth W., Heat Pump Installation
"I have used Emergency Air for 5 years for routine maintenance, repair and replacements of my Central heat pump systems. ... Calab was able to quote me the same unit to replace the current dangerous one ... I can recommend Emergency Air for your heating and AC needs."
–Donald H., Heating Service
"They swapped out our old split system for a new heat pump. Did all of it in 6-7 hours."
–Everett H., Heat Pump Replacement

Frequently Asked Questions

Why is my heater not working after a power outage?

Power blips can lock out controls. Turn the furnace or air handler Off for 5 minutes, then back On. Check breakers and outdoor heat pump disconnects. If it still fails, a technician should test the control board and safeties.

How often should I replace my furnace filter in Arizona?

Check monthly and replace as needed. Dust, pets, and tile floors increase buildup. Many homes do best with a MERV 8 to 11 filter changed every 1 to 3 months.

Is it normal for my heat pump to blow cooler air?

Yes. Heat pumps deliver warm but not hot air and may enter a defrost cycle on cold mornings. If rooms never reach setpoint or bills spike, schedule a performance check.

What does a $59 furnace tune‑up include?

It includes a 20‑point inspection, electrical and safety checks, airflow assessment, and performance test. We share findings with upfront repair pricing and photos on request.

When should I consider replacing my heater instead of repairing?

If the unit is 15 to 20 years old, has a cracked heat exchanger or failing compressor, or repair costs exceed 30 percent of replacement, a new high‑efficiency system often saves money and improves comfort.

Bottom Line

If your heater is not working, start with simple checks. Thermostat settings, breakers, and filters solve many issues. For ignition failures, airflow problems, or persistent shutdowns, our licensed team will diagnose and fix it right the first time.

We serve Phoenix, Mesa, Chandler, Gilbert, Scottsdale, and nearby cities. Call now for fast help and savings.

Ready for Heat Again? Call, Schedule, or Chat

  • Call 24/7: (602) 894-9228
  • Book online: https://www.emergencyair.com/
  • Today’s savings: $59 Furnace Tune‑Up or Free Diagnostic With Repairs. Mention this blog when you schedule.

Your comfort is our emergency. Get same‑day service and upfront pricing today.

About Emergency Air Heating and Cooling

For over 20 years, Arizona homeowners have trusted Emergency Air Heating and Cooling. We are a Carrier Factory Authorized Dealer and multi‑year Carrier Presidents Award winner with an A+ BBB rating and the BBB Ethics Award. Our background‑checked, drug‑tested technicians provide upfront pricing, 24/7 emergency response, and a 100% satisfaction guarantee. Your comfort is our emergency.

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