Unlock the Right Part
for Your Repair
Find the exact part you need
Enter your model number to see parts that fit your machine.
Price Match Guarantee
In-stock parts ship the same day
365-Day Return Policy
Price Match GuaranteeChoose Product
Identify Problem
03
Find Solutions
HomeRepair HelpCarrier A/C RepairCarrier Air conditioner won't turn off Repair
Carrier Air conditioner won't turn off
If your Carrier air conditioner won’t turn off, start with the parts and conditions most likely to make the AC run continuously. Dirty condenser coils are the top suspect because they cannot release heat efficiently, so the compressor keeps running while the unit struggles to reach the set temperature. Next, check the temperature control thermostat and thermostat. If either one is shorted or defective, it can keep sending voltage to the fan motor and compressor, causing the air conditioner compressor to run constantly. A dirty or damaged air filter can also reduce airflow and cooling capacity enough that the air conditioner keeps running longer than it should. Less commonly, a faulty thermistor may misread room temperature and tell the control board to keep cooling, while a bad relay board can send continuous voltage to the compressor. Clean the coils and filter first, then test electrical parts with a multimeter and your wiring diagram. Enter your Carrier model number on RepairClinic.com to find the exact replacement thermostat, thermistor, relay board, filter, or other part for your specific air conditioner.
01 - Condenser Coils are Dirty
The condenser coils dissipate the heat as the refrigerant passes through the coils. If the condenser coils are dirty, they won’t be able to dissipate the heat as effectively. As debris builds up on the coils, the air conditioner will become less efficient, causing the air conditioner to work harder to cool down. If the coils are significantly dirty, the air conditioner will not be able to maintain the proper temperature, and the compressor will run continuously in an attempt to cool the room. Check the condenser coils to determine if they are dirty. Refer to owner's manual for cleaning instructions.
Top Solution
02 - Carrier Air Conditioner Temperature Control Thermostat
The temperature control thermostat provides voltage to the fan motor and compressor. If the thermostat has shorted out, it might send continuous voltage to the compressor and cause the compressor to run all the time. To determine if the thermostat is shorted out, use a multimeter to test it for continuity. If the thermostat has continuity all the time, this indicates that it is shorted out and should be replaced. (Note: Some thermostats may also control a heater and, as a result, will have three terminals. Refer to your air conditioner’s wiring diagram for more information.)
Enter model number to search for the required part specific to your product
Highly Likely
03 - Carrier Air Conditioner Thermostat
The thermostat monitors the temperature of the air. When the air temperature rises above a set point, the thermostat activates a switch to provide power to the fan and compressor. If the thermostat is defective, it may cause the compressor to run continuously. To determine if the thermostat is defective, set the air conditioner to cooling and then use a multimeter to test the thermostat for continuity. If the thermostat does not have continuity while the air conditioner is set to cooling, replace the thermostat. (Note: Some thermostats may also control a heater and, as a result, will have three terminals. Refer to your air...
Highly Likely
04 - Dirty or Damaged Air Filter
A dirty air filter will greatly reduce the cooling capacity of the air conditioner, which may cause the unit to run longer than normal. Most air filters used in stand-alone air conditioners can be cleaned with soap and water. Only filters that are extremely clogged with debris or damaged will need to be replaced. Refer to owner's manual for guidance.
Common
05 - Carrier Air Conditioner Thermistor
The thermistor is a sensor which detects the room air temperature. It is connected to the control board. If the thermistor is defective it will not have continuity when it should. If this happens the compressor runs all the time.
Common
06 - Carrier Air Conditioner Relay Board
The relay board provides voltage to many of the air conditioner components, including the fan motor and compressor. If there is a problem with the relay board, it might provide continuous voltage to the compressor. However, this is almost never the case. Before you replace the relay board, make sure you check more commonly defective parts. If you are certain that all of the other components are working properly, replace the relay board.
Common
Frequently Asked Questions
Why won't my Carrier air conditioner turn off?
Why does my Carrier AC run continuously but not cool well?
How do I test a Carrier air conditioner thermostat that may be stuck on?
Can a bad thermistor make a Carrier air conditioner compressor run constantly?
How do I find the right replacement part for my Carrier air conditioner?
Shop by Carrier Air Conditioner Parts
Shop by Popular Carrier Air Conditioner Models
Our Story
Family-owned and operated since 1912, Burke America Parts Group is the longest-running genuine appliance, HVAC, and outdoor power equipment parts solution in North America. At Repair Clinic, we're proud to be an international brand trusted by the pros as well as the DIY community.
About Repair Clinic
© 2026 RepairClinic.com