KeepRite Error Code Green COMM LED off: No communication yet (AC)

Updated October 16, 2026 · by Aurora Star Tech Inc.

KeepRite error code Green COMM LED off on a air conditioner means: No communication yet. It is also called KeepRite diagnostic code Green COMM LED off.

Low severityAir ConditionerKeepRite C4A3/CXA6 AC

Homeowner? What KeepRite code Green COMM LED off means for you

Usually minor Your air conditioner is reporting: No communication yet. 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) 657-2977 Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does KeepRite error code Green COMM LED off mean?

The green COMM light is dark. It stays off after power-up until the board receives a valid communicating command, and goes off again if nothing valid arrives for 2 minutes. On a unit wired to a plain thermostat this is expected.

Applies to: C4A3/CXA6 A-C (communicating control)

Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

KeepRite models that use code Green COMM LED off

C4A3 CXA6

Other KeepRite AC codes

Code	Meaning
Amber 2 flashes	High stage running (normal)
Amber 5 flashes	Brown-out protection turned off (user setting)
Amber 6 flashes	Brown-out protection active (user setting)
Amber LED off	Standby - no call (2-wire hookup or indoor unit unpowered)
Amber LED on solid	Standby - no call (communicating)
Brown-out defeat toggle	Turn 230 V brown-out protection off or on
Green COMM LED on	Communication with the system established
Green POWER LED	Comfort Alert module has power
Red TRIP LED	Comfort Alert TRIP - Y call but compressor not running
TRIP + ALERT flashing together	Comfort Alert - control voltage too low to operate

All KeepRite Air Conditioner error codes →

KeepRite code Green COMM LED off: homeowner questions

What does KeepRite code Green COMM LED off mean?

No communication yet. The green COMM light is dark. It stays off after power-up until the board receives a valid communicating command, and goes off again if nothing valid arrives for 2 minutes. On a unit wired to a plain thermostat this is expected.

Is it safe to keep using my air conditioner with code Green COMM LED off?

Usually yes. Code Green COMM LED off is normally minor, but if it keeps coming back have it checked.

Can I reset KeepRite code Green COMM LED off myself?

You can try one reset (power off for 30 seconds, then on). If KeepRite code Green COMM LED off comes back, the cause is still there and a licensed technician should check it.

Who can fix KeepRite code Green COMM LED off near me?

Aurora Star Tech Inc. repairs KeepRite 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

Bubbles in sight glass / temperature drop across liquid line drier All brands · Air Conditioner
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General service-call symptom list All brands · Air Conditioner
Hard starting / stalls on restart All brands · Air Conditioner
Humid indoor air All brands · Air Conditioner
Insufficient cooling, frost at outlet of liquid-line filter-drier, both pressures and amps dropping All brands · Air Conditioner
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Liquid floods back to compressor on start / liquid refrigerant in cold condenser All brands · Air Conditioner
Low head pressure persists in winter, or loss of capacity in summer All brands · Air Conditioner
Low head pressure, starved evaporator, high superheat and high subcooling readings, short cycling, poor cooling in winter All brands · Air Conditioner
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No cooling All brands · Air Conditioner
No cooling via stat All brands · Air Conditioner
No cooling, compressor and condenser fan both dead, supply voltage present at disconnect All brands · Air Conditioner
No cooling, compressor runs, condenser fan off, very high head, compressor cycling on overload All brands · Air Conditioner
No cooling, system running, house 81°F at 72°F set, high temp split, low suction, ice on coil All brands · Air Conditioner
Noisy All brands · Air Conditioner
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Outdoor unit won't start, 24 V present at contactor coil All brands · Air Conditioner
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Rust on accumulator / vibration absorber leaks All brands · Air Conditioner
Starved evaporator (partial frost, poor cooling) All brands · Air Conditioner
Superheat above target All brands · Air Conditioner
Superheat below target All brands · Air Conditioner
System short cycles All brands · Air Conditioner
Thermostat suspected All brands · Air Conditioner
Undercharged system: compressor runs continuously, poor cooling, high power use, warm liquid line and drier All brands · Air Conditioner
Water dripping inside All brands · Air Conditioner
Won't engage All brands · Air Conditioner
Won't start / no cooling All brands · Air Conditioner
Checking OAT and OCT thermistors - KeepRite C4A3/CXA6 KeepRite · Air Conditioner
Turn 230 V brown-out protection off or on KeepRite · Air Conditioner

Source: KeepRite ICP C4A3/H4A3/T4A3/CXA6 A-C Installation Instructions 421 01 5103 05, Communication and Status Function Lights, p.17. 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.