Your air conditioning system relies on several critical components to operate safely and efficiently one of which is the limit switch. Though it might not be as well known as the thermostat or compressor, the limit switch plays a vital role in protecting your HVAC system and ensuring your home stays comfortable. Ambient Heating & Air Conditioning would like to explain what an air conditioner limit switch is, why it is important, the signs it’s failing, and what to do if yours goes bad.
What is a Limit Switch in an Air Conditioner System?
A limit switch is a safety device found in your air handler or furnace. Its main job is to monitor the temperature of the system’s components, specifically the heat exchanger or evaporator coils, depending on whether it is part of a heating or cooling cycle. If temperatures exceed safe levels, the limit switch will shut down the system or the blower motor to prevent overheating or further damage. The limit switch ensures:
• Prevent overheating
• Protect the blower motor and other internal parts
• Ensure safe operation of the HVAC system
Some systems also include a fan limit switch, which tells the blower fan when to turn on and off based on temperature improving both comfort and efficiency.
What Happens When a Limit Switch Fails?
If a limit switch becomes faulty or fails entirely, it can cause serious problems. Here’s what you might experience:
Blower Fan Runs Constantly: If the limit switch fails in the “closed” position, it may send a constant signal for the blower to run even when the system is not heating or cooling. This wastes energy and can overwork your motor.
System Shuts Down Prematurely: If the switch falsely detects high temperatures, it can shut down the system too early even if there’s no real danger. This results in uneven cooling and frequent cycling.
No Air from the Vents: In some cases, a faulty limit switch might prevent the fan from turning on at all. If you don’t feel any airflow, even though your thermostat is calling for cooling, a failed switch could be the cause.
Error Codes or Alerts: Many modern HVAC systems will display an error code or flash a warning light if a limit switch malfunction is detected. This is your system’s way of telling you something needs attention.
What to Do if Your Limit Switch Fails
Replace Your Air Filter: Sometimes, airflow restrictions from a dirty air filter can cause the system to overheat and trip the limit switch. Replacing the filter may resolve the issue if the switch is still functioning.
Check for Blocked Vents: Ensure all vents and registers are open and unobstructed to allow for proper airflow.
Reset the System: Turn off the power to the unit at the breaker for a few minutes, then turn it back on. This may reset the system, but it won’t fix a faulty switch.
Call a Professional HVAC Technician: If basic troubleshooting does not work, it is time to call in a professional. A licensed HVAC technician can test the limit switch, determine if it is failing, and replace it if necessary.
Central Air Conditioner Maintenance, Replacement, Emergency Repairs & More in Springfield, Granby, Holyoke, South Hadley, Monson, Chicopee & Agawam, Massachusetts
If your air conditioner is acting up, running constantly, or not blowing air at all, our expert technicians are ready to help. Contact Ambient Heating & Air Conditioning today to schedule a service our services today.