Carrier Error Code 4: Four flashes – speed limiting, non-communicating thermostat (AC)
Carrier error code 4 on a air conditioner means: Four flashes - speed limiting, non-communicating thermostat. It is also called Carrier diagnostic code 4.
Homeowner? What Carrier code 4 means for you
Usually minor Your air conditioner is reporting: Four flashes - speed limiting, non-communicating thermostat. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.
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 4 mean?
Four flashes and a pause on the amber STATUS LED of the 24VNA9 when it runs from a non-communicating thermostat. It shows reduced capacity with compressor speed limited. This is an operating state, not a lockout.
Applies to: Carrier Infinity 24VNA9 variable speed air conditioner
Carrier models that use code 4
24VNA924VNA91324VNA92424VNA92524VNA93624VNA93724VNA94824VNA94924VNA960
Other Carrier AC codes
All Carrier Air Conditioner error codes →
Carrier code 4: homeowner questions
What does Carrier code 4 mean?
Four flashes - speed limiting, non-communicating thermostat. Four flashes and a pause on the amber STATUS LED of the 24VNA9 when it runs from a non-communicating thermostat. It shows reduced capacity with compressor speed limited. This is an operating state, not a lockout.
Is it safe to keep using my air conditioner with code 4?
Usually yes. Code 4 is normally minor, but if it keeps coming back have it checked.
Can I reset Carrier code 4 myself?
You can try one reset (power off for 30 seconds, then on). If Carrier code 4 comes back, the cause is still there and a licensed technician should check it.
Who can fix Carrier code 4 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
- Recall the active status code on the outdoor board (25VNA8/24VNA9) Carrier · Air Conditioner
- Refrigerant charging mode on Infinity control (25VNA8/24VNA9) 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 25VNA8/24VNA9 service manual, Table 6, p.15-16. 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.