Honeywell Thermostats

Re: Red Light on Thermostat Flashing

Some York Heat Pumps have a diagnostic board that will flash a light or display "Error 40" at the thermostat when a fault condition occurs.

• The light will flash a certain number of times, pause, then flash the same number again.
• The flashing light indicates that there is a diagnostic issue with the heat pump.

Older Units (before 2010): will display the actual fault code at the thermostat by flashing a code from 2 to 9.

• All codes can be Reset by doing either of the following:
  • Turning the thermostat system switch to "Off" for about 1 minute then back to either "Heat", "Cool" or "Auto" 
  • Cycling power to the air handler (turning the breakers off and then back on).

Newer Units (after 2010): will only flash a Code 2, 3 or 4 at the thermostat (the actual fault code must be read at the outdoor unit control board).

• 2 Flash - is a soft lockout that can be Reset by doing either of the following:
  • Turning the thermostat system switch to "Off" for about 1 minute then back to either "Heat", "Cool" or "Auto" 
  • Cycling power to the air handler (turning the breakers off and then back on).
• 3 Flash - is a Hard Lockout which can only be Reset by cycling power to the air handler.
• 4 Flash - indicates a wiring, sensor or control setting error.

WHAT CAN THE CUSTOMER DO:

• Check their breaker box to make sure no breakers are tripped.
• Make sure the air filter is clean.
• Attempt a Reset by one of the 2 methods mentioned above.
• Service Appointment
  • Schedule a service appointment now or wait to see if the alert returns.