Sometimes your window air conditioner tells you exactly what's wrong, as long as you can crack the code. Below are common error code tables for the most popular brands, along with an explanation of what the code means, possible repair parts you might need and DIY advice.
Code |
Meaning |
Possible Cause |
ES |
Evaporator temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the evaporator temperature sensor wire harness. Replace the evaporator temperature sensor if it's defective. Possible parts - Evaporator temperature sensor, Wire harness, Electronic control board |
AS |
Ambient temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the ambient temperature sensor wire harness. Replace the ambient temperature sensor if it's defective. Possible parts - Ambient temperature sensor, Wire harness, Electronic control board |
HS |
Air outlet temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the air outlet temperature sensor wire harness. Replace the air outlet temperature sensor if it's defective. Possible parts - Air outlet temperature sensor, Wire harness, Electronic control board |
OS |
Outdoor temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the outdoor temperature sensor wire harness. Replace the outdoor temperature sensor if it's defective. Possible parts - Outdoor temperature sensor, Wire harness, Electronic control board |
CS |
Condenser temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the condenser temperature sensor wire harness. Replace the condenser temperature sensor if it's defective. Possible parts - Condenser temperature sensor, Wire harness, Electronic control board |
Error Code |
Condition |
Check Repair |
E1 |
Electronic control board function error |
Unplug the window air conditioner for 1 minute and then plug it back in to reset the electronic control board. If the code doesn't clear, unplug the window air conditioner and check the wire harness connections on the electronic control board. Check the electronic control board for visible damage such as a burn mark. Replace the electronic control board if it's damaged or defective. Possible parts - Electronic control board, Wire harness |
E4-Portable A/Cs only |
Water bucket is full or defective bucket float switch |
If the collection bucket is full, empty the bucket. If the bucket isn't full, unplug the air conditioner and check the wire harness connections on the electronic control board. Check for a pinched or damaged wire in the wire harness between the electronic control board and the collection bucket float switch. Check the float switch for damage. If the float switch is defective, replace it. Possible parts - Float switch, Wire harness, Electronic control board |
Code |
Meaning |
Possible Cause |
ES |
Evaporator temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the evaporator temperature sensor wire harness. Replace the evaporator temperature sensor if it's defective. Possible parts - Evaporator temperature sensor, Wire harness, Electronic control board |
AS |
Ambient temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the ambient temperature sensor wire harness. Replace the ambient temperature sensor if it's defective. Possible parts - Ambient temperature sensor, Wire harness, Electronic control board |
HS |
Air outlet temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the air outlet temperature sensor wire harness. Replace the air outlet temperature sensor if it's defective. Possible parts - Air outlet temperature sensor, Wire harness, Electronic control board |
OS |
Outdoor temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the outdoor temperature sensor wire harness. Replace the outdoor temperature sensor if it's defective. Possible parts - Outdoor temperature sensor, Wire harness, Electronic control board |
CS |
Condenser temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the condenser temperature sensor wire harness. Replace the condenser temperature sensor if it's defective. Possible parts - Condenser temperature sensor, Wire harness, Electronic control board |
Code |
Meaning |
Possible Cause |
E1 |
Temperature sensor failure |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the temperature sensor wire harness. Replace the temperature sensor if it's defective. Possible parts - Temperature sensor, Wire harness, Electronic control board |
E2 |
Failure in the indoor temperature sensor |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the indoor temperature sensor wire harness. Replace the indoor temperature sensor if it's defective. Possible parts - Indoor temperature sensor, Wire harness, Electronic control board |
E3 |
Abnormal operation protection error |
Unplug the air conditioner and check the wire harness connections on the electronic control board. Examine the electronic control board for damage. Check for a pinched or broken wire in the air outlet temperature sensor wire harness. Replace the air outlet temperature sensor if it's defective. Possible parts - Indoor temperature sensor, Wire harness, Electronic control board |
E3 |
Abnormal operation protection error |
Clean or replace filters if dirty. Unplug the window air conditioner and check all components for visible damage. Check fan blades for damage or obstructions and replace any damaged fan blades. Check all wire harness connections. Replace any damaged wire harnesses. Possible parts - Filter, Fan blade, Fan motor, Wire harness |
E4-Portable A/C only |
Air conditioner is in the defrost mode |
After the air conditioner exits defrost mode and resumes normal operation, check the unit to see if it's cooling properly. If so, then the E4 code is normal. If the portable air conditioner frequently goes into the defrost mode and isn't cooling properly, check the air filters and clean or replace filters if dirty. Possible parts - Filter |
P2 or FL-Portable A/C only |
Water collection tank is full |
Empty the water collection tank. If the P2 or FL code appears when the tank is empty, replace the float switch or sensor in the collection tank. Possible parts - Collection tank float switch or sensor |