How to Resolve the Rheem Air Handler That Won't Shut Off

A malfunctioning air handler can disrupt the efficiency of your HVAC system, and one of the most common issues is when your Rheem air handler refuses to shut off. This problem can result in higher energy costs, increased wear on the system, and general discomfort. If you understand what is causing the problem and how to fix it, you can restore the system’s performance and stop any further damage from occurring. We'll cover the most frequent causes of your Rheem air handler not shutting off in this post, along with solutions.

Causes & Fixes for Rheem Air Handler That Won’t Shut Off

There are a few reasons your Rheem air handler may run continuously. These are the most frequent causes of this problem, along with practical solutions.

1. Faulty Thermostat Settings

One of the simplest reasons your air handler might not shut off is incorrect thermostat settings. If your thermostat is set to "on" rather than "auto," the fan will continue to run even after the heating or cooling cycle is complete.

Solution:

If you are experiencing this issue, confirm that your thermostat is set to "auto." The fan will only operate in "auto" mode when the system is actively heating or cooling, and it will turn off when the temperature is attained. If the thermostat still isn’t working, you may want to replace or recalibrate it.

2. Malfunctioning Control Board

The control board of your Rheem air handler is responsible for regulating the system’s components, including the blower motor. If the control board is bad, it may send the wrong signal and the blower motor will run forever.

Solution:

It's advisable to contact a qualified HVAC specialist if you think the problem is with the control board. They can identify the issue and, if required, swap out the control board. Since a malfunctioning control board might also impact other parts, expert assistance is frequently needed.

3. Stuck Fan Relay

The blower motor turns on and off controlled by the fan relay. If the relay marshals in the "on" position, then the air handler will continue to run, until the time that it should be shut off.

Solution:

One way to treat a stuck fan relay problem is to replace the faulty relay. Typically this is a job for an HVAC professional to safely replace the component and make sure the system is working properly.

4. Dirty or Clogged Air Filters

If the air filters in your Rheem air handler become dirty or clogged, they can begin to restrict airflow and, as a result, your system can start working harder than it needs to. This means it could continue to run in an effort to reach the desired temperature, even when the cycle is finished.

Solution:

Make sure to clean or replace the air filters regularly to ensure proper airflow and reduce the strain on the system. You should replace air filters every 1 to 3 months, but it may be more frequent, depending on your environment.

5. Faulty Limit Switch

The limit switch is a safety device that prevents the air handler from overheating by limiting the temperature inside the unit. A faulty limit switch may not signal the system to shut off, and therefore the system continues to run.

Solution:

If the limit switch is bad, you will have to replace it. Because working with electrical components is dangerous, this is another repair that needs to be fixed by an HVAC technician.

6. Refrigerant Leaks (Cooling Mode)

If your Rheem air handler is part of an air conditioning system and you’re having problems with the system not turning off, it could be because of a leak that is causing low refrigerant levels. Low refrigerant can render the system inefficient to operate and continue on and on… trying to reach the set temperature.

Solution:

A qualified HVAC professional should handle any refrigerant leaks you may have. They can identify the leak, fix it, and add the appropriate amount of refrigerant to recharge the system. It can damage the compressor so you need to take prompt action.

7. Short Cycling

Short cycling is when the air handler starts and stops extremely quickly, not doing a full cooling or heating cycle. This can last longer than necessary and thus makes it seem as if the system just isn’t turning off.

Solution:

Check for issues such as clogged air filters, low refrigerant, or improper thermostat settings. In some cases, short cycling can be resolved by addressing airflow restrictions or ensuring that the thermostat is placed in an optimal location.

If your Rheem air handler is refusing to shut off, you should quickly determine and fix the underlying problem. To restore your system's functionality and stop more issues, timely repairs, and routine maintenance are essential. If the issue persists or you’re unsure about making repairs yourself, contacting a professional HVAC technician will help ensure the problem is resolved effectively and your system continues to operate smoothly.

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