Carrier Error Code 81: Low stage thermal lockout (AC)
Carrier error code 81 on a air conditioner means: Low stage thermal lockout. It is also called Carrier diagnostic code 81.
Homeowner? What Carrier code 81 means for you
Call a technician Your air conditioner is reporting: Low stage thermal lockout. The air conditioner has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- Keep about 2 feet around the outdoor unit clear of leaves, grass and debris.
- If you see ice on the pipes or the indoor coil, turn the system off and run only the fan for a few hours, then call a technician.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Carrier error code 81 mean?
Amber STATUS light flashes 81: the compressor thermal protector tripped in low stage three cycles in a row; low stage is locked out for 4 hours or until 24 V is cycled.
Applies to: Carrier 24ANB1/24ANB7 two-stage AC
Common causes of Carrier code 81
- Compressor internal overload repeatedly tripping
- Start relay/capacitor staying in circuit too long
- Low voltage, poor airflow or charge problem
Carrier models that use code 81
24ANB12424ANB13624ANB14824ANB16024ANB72424ANB73624ANB74824ANB760
Other Carrier AC codes
All Carrier Air Conditioner error codes →
Carrier code 81: homeowner questions
What does Carrier code 81 mean?
Low stage thermal lockout. Amber STATUS light flashes 81: the compressor thermal protector tripped in low stage three cycles in a row; low stage is locked out for 4 hours or until 24 V is cycled.
Is it safe to keep using my air conditioner with code 81?
It depends on the cause. The air conditioner has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Carrier code 81 myself?
You can try one reset (power off for 30 seconds, then on). If Carrier code 81 comes back, the cause is still there and a licensed technician should check it.
Who can fix Carrier code 81 near me?
Aurora Star Tech Inc. repairs Carrier air conditioners in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: AC Running But Not Cooling: What to Check
Troubleshooting guides
- Not cooling All brands · Air Conditioner
- Amber STATUS or green COMM light not on Carrier · Air Conditioner
- Compressor will not run - winding and electrical checks - Carrier split systems Carrier · Air Conditioner
- Delay before the compressor restarts Carrier · Air Conditioner
- Hissing from the outdoor unit after it shuts off Carrier · Air Conditioner
- Outdoor unit unresponsive after several faults Carrier · Air Conditioner
- Superheat too high or too low on TXV system - Carrier split systems Carrier · Air Conditioner
- Two-stage unit not changing stages - Carrier 24ANB/25HNB/25HCB6 Carrier · Air Conditioner
Source: Carrier Residential AC & HP Application Guideline and Service Manual 24-25-9SM (text export), Table 18 Troubleshooting. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.