Air Handler Not Turning On

If your heat pump or air handler is not turning on, you’re stressing. You’re either hot or you’re cold, and family members may be complaining. Find out what’s causing the issue and what you can do to get comfortable again.

This may seem silly, but before you call for HVAC repair, check the thermostat. Make sure it’s set to heat or cool, and that the indoor temperature is less than or greater than what your set temperature is. Make sure the fan is set to ON or AUTO. If the thermostat has batteries, change them out if it’s been a while.

If the thermostat is set correctly, but the air handler still isn’t turning on, ensure that there is power to the unit. Some units have what looks like a light switch near them. Make sure it’s in the ON position. You can also check your circuit breaker box. If the breaker is tripped, call for HVAC repair rather than flipping the breaker. If it tripped, there may be an issue with the air handler, and powering it back up could damage your system.

A clogged filter can cause your air handler to shut off. Check the filter and change it if it’s dirty. Get in the habit of changing it every 30-90 days, depending on the filter. Refer to our HVAC air filter maintenance guide for some tips.

If your air handler still won’t turn on, call for help.

Once an HVAC technician arrives on the scene, they will check numerous things, not necessarily in this order.

The HVAC technician will open up your air handler to see what’s going on. They will check for a faulty relay as well as a faulty control board. The control board is the brain of the unit.

The technician will also check for loose or frayed wiring. Bad connections can prevent the air handler from turning on.

The air handler’s operation is powered by the blower motor, which has a run capacitor. If the capacitor is bad, the unit may not be able to start.

The blower motor may be the source of the problem. The motor can overheat and shut the unit down, causing the fan to stop. Overheating can be caused by a faulty run capacitor, a clogged filter, and other issues.

One more reason for the air handler not working is a frozen evaporator coil. It struggles to pull air through the coil, and the blower motor can overheat and shut down. If the blower fan isn’t being powered, it can cause the coil to freeze. If you have a frozen evaporator coil, the technician will try to determine why, and if you have a refrigerant leak.

To help keep your HVAC system running smoothly, change the air filter every 1-3 months, depending on the type of filter. Keep the outdoor unit clear of debris and encroaching vines or shrubbery.

In addition, schedule AC maintenance every spring and heat pump maintenance in the spring and fall. During a professional HVAC maintenance visit, the technician will check the outside unit as well as the indoor air handler for issues and provide a tune-up of sorts.

If you have a Trane smart thermostat, you can opt into Trane Diagnostics via the Trane Home App. All the time the HVAC technician spends troubleshooting your system goes away if you have remote monitoring and remote diagnostics enabled.

With remote diagnostics, your Trane dealer can monitor your system 24/7. If and when there is a problem, they can ask you for one-time remote access to get inside your system remotely and do some troubleshooting. They may even be able to fix the problem remotely.

If the problem requires an on-site visit, the technician arrives with the troubleshooting already complete and can get your home comfortable again more quickly.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Kimberly Sexton, Senior Systems Engineer

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