While you might not always notice it, your air handler unit (AHU) is an essential part of your heating, ventilation, and air conditioning (HVAC) system. If it starts to malfunction, you may notice poor airflow, weak performance, unusual noises, and overheating. Through the right AHU troubleshooting, you can fix basic issues. If these basic steps don’t work, Central Air Heating, Cooling & Plumbing can help you quickly diagnose and repair complex AHU issues.
What the Air Handler Actually Does
The AHU is the indoor portion of your HVAC system. It is responsible for circulating the conditioned air in your home.
Within the AHU, you’ll also find the evaporator coil, air filter, and blower. If any of these interior components malfunction, it can lead to performance and airflow issues.
Most Common Air Handler Unit Problems
Most air handler unit problems are due to four basic causes. Airflow restrictions, electrical issues, refrigerant problems, and drainage malfunctions can lead to the air handler not working properly. If you’re experiencing any of these problems, give us a call at (971) 435-7303.
Air Handler Running but Not Heating or Cooling
When a cooling system’s air handler is blowing warm air, it is often related to a clogged filter, a tripped breaker, incorrect thermostat settings, or low refrigerant levels. A furnace may blow cold air due to a dirty filter, faulty igniter, or incorrect thermostat settings. By scheduling an AC, furnace, or heat pump repair, you can determine the underlying cause.
Blower Fan Not Running
This problem can occur due to dead batteries, a faulty capacitor, failing motor bearings, or control board issues. While dead batteries can be dealt with on your own, the other issues should be handled by a professional.
Weak or Uneven Airflow
When airflow is weak or uneven, it’s a good idea to replace the air filter and make sure your home’s vents are unobstructed. Our HVAC technicians can also inspect your ducts for leaks and gaps.
Air Handler Leaking Water
If the air handler is leaking water, you may have a clogged condensate drain line. The good news is that this problem is often easily fixed by flushing the drain line and removing the clog.
Frozen Evaporator Coil
Dirty air filters, low refrigerant, and airflow issues can cause the evaporator coil to freeze. While you can change the filter yourself, airflow and refrigerant problems should be inspected by a professional.
Unusual Noises Coming From the Air Handler
Strange noises can be connected to loose components, debris in the unit, faulty motor bearings, or blower motor malfunctions. In general, this is an issue that is best left to the experts.
Air Handler Short-Cycling or Running Constantly
This type of problem often stems from dirty filters, thermostat malfunctions, low refrigerant, or airflow-related problems.
Safe Checks To Make Before Calling
Before you call for professional repairs, there are a few AHU troubleshooting steps you can try on your own first.
Check the Thermostat and Mode Setting
Verify that the thermostat is set to the correct mode and temperature.
Inspect the Air Filter
See if your filter is dirty. Depending on the manufacturer and your usage, the filter should be replaced every 30 to 90 days.
Check the Condensate Drain Line
If water is coming from the unit, you may have a clogged drain line. You can flush the line with vinegar. For tougher clogs, reach out for professional HVAC services.
Look at the Breaker Panel
You can reset the breaker if it has tripped. For your safety, don’t keep resetting a tripped breaker over and over because repeatedly tripped breakers indicate an underlying electrical problem.
What Our Technicians Check During an AHU Diagnosis
During the diagnostic appointment, our team will check the condition of your filter, coils, condensate drain line, and drive assembly. We will test your thermostat and sensors to make sure they are working properly. To troubleshoot electrical problems, our technicians will also test the capacitor’s microfarad rating, tighten electrical connections, and check the voltage.
Getting a routine inspection is important in Portland’s unique climate. Because the temperature is often mild, air handlers can sit unused for months. As a result, many homeowners are surprised when the first sustained cold snap or heat wave arrives, and the AHU doesn’t work. Through a routine tune-up, you can detect minor issues before they can escalate into an HVAC failure.
When To Repair vs. Replace the Air Handler
While many factors go into the decision to repair or replace your AHU, the commonly used $5,000 rule is a good starting point. Take the cost of repairs and multiply it by the age of the unit. If the result is over $5,000, a replacement is likely the better choice.
FAQs
Can a dirty filter cause the air handler to freeze up?
Absolutely. Because the dirty filter decreases airflow, the evaporator coil can’t absorb heat. Eventually, the coil may freeze up.
Why is my air handler running, but no air is coming out of the vents?
This typically occurs if the blower motor is malfunctioning, the filter is clogged, or the evaporator coil is frozen. You can replace the filter and wait for the coil to thaw on its own. Make sure to shut off your unit while the coil thaws. For blower motor issues, professional heating and cooling repairs are necessary.
What causes a banging or rattling sound from the air handler?
An air handler making noise may be due to worn blower motor bearings, loose components, debris in the unit, or issues with the blower motor. While you can tighten visible components yourself, you should leave other maintenance and repair tasks to the professionals.
How long should an air handler last?
A standard air handler can last as long as 15 to 20 years. However, this lifespan is greatly impacted by maintenance consistency, climate, and usage intensity.
Schedule AHU Service in Portland
Over the years, Central Air Heating, Cooling & Plumbing has helped Portland and Clackamas homeowners with all types of HVAC repairs and replacements. If your AHU troubleshooting is unsuccessful, we can help you diagnose and resolve the problem.
We’re available 24/7 for emergency breakdowns. Through our zero-risk repairs, you can rest easy with the knowledge that your HVAC repairs are guaranteed for three years. Learn more about our HVAC repair and replacement options by giving us a call today at (971) 435-7303.