York furnace 4 amber flashes: Cooling called with no fan call
Four amber flashes means a cooling call arrived without an accompanying fan call. The air conditioner has been asked to run with nothing moving air over the coil.
Applies to: York, Luxaire and Coleman gas furnaces using the UTEC or W/R integrated furnace control boards documented in technical service letter ST-045-09.
What it means
In a conventional system the thermostat sends a cooling call and a fan call together, because cooling without airflow does nothing useful and can freeze the indoor coil. This code means the furnace received the cooling signal without the fan signal. The furnace is fine — it is reporting that the instructions do not make sense together. Like the staging code, this is a thermostat wiring or configuration fault, and it appears most often after a thermostat replacement where the fan wire was not connected or the thermostat was set up for the wrong equipment.
Most common causes
- The fan wire not connected at the thermostat or at the furnace.
- A broken fan wire between the thermostat and the furnace.
- A thermostat configured for the wrong equipment type.
- A smart thermostat set up without a fan connection.
- A zone control board not passing the fan call through.
- A thermostat fault where the cooling output works and the fan output does not.
How to diagnose it
- Establish whether the thermostat has been replaced or reconfigured recently.
- Confirm the colour is amber and not red. Four red flashes on these boards is an open high limit, a completely different situation.
- Note whether the air conditioner appears to run without air coming from the registers.
- Check whether the blower runs when the thermostat's fan setting is switched to on, which tests the fan circuit directly.
How to fix it
- Have the thermostat wiring checked against the furnace terminals, particularly the fan connection.
- Configure the thermostat correctly for the equipment if it is a settings issue.
- If a wire has broken, that needs tracing — technician work, though straightforward.
- Do not run cooling in this state. An indoor coil running without airflow can freeze, and a frozen coil is a longer repair than a wiring correction.
Notes
Although this is a cooling code it appears on the furnace, because the furnace's blower moves the air for both heating and cooling. That surprises people who expect an air conditioning fault to show at the outdoor unit.
Related
All codes for this manufacturer
York, Luxaire and Coleman furnace flash codes — every code, with what differs between models.