Why doesn't my Honeywell Control Unit compressor turn on, and the “Y” LED is blinking?
The compressor might not be turning on, and the “Y” LED might be blinking due to a 5-minute compressor lockout that occurs after a power cycle. Wait 5 minutes, and the compressor will turn on after the safety timeout.
What to do if the Honeywell Control Unit thermostat shows “—” for outdoor temperature?
If the thermostat displays “—” for the outdoor temperature, it indicates that the wired outdoor temperature sensor has failed. Check the sensor for a short circuit or an open circuit.
Why is the outdoor temperature reading at the Honeywell Control Unit thermostat too high?
An outdoor temperature reading at the thermostat that is too high is usually caused by sun load on the sensor. Make sure the outdoor temperature sensor is not in direct sunlight. You may need to use a longer wire to mount it in an ideal location.
How to fix relays that don’t switch as expected on a Honeywell Control Unit?
If the relays aren’t switching as expected, the cause may be incorrect jumper configuration. Check the jumper configuration. If it is incorrect, unenroll from the system, change the jumper, and then re-enroll with the system.
What to do if the connected LED on my Honeywell Control Unit is red?
If the connected LED is red, it indicates a loss of communication with the system. Verify that the thermostat and/or Equipment Interface Module are powered and functioning correctly.
Why is there no outdoor temperature shown on my Honeywell Control Unit thermostat?
If there is no outdoor temperature shown on the thermostat, it may be because there is no wired outdoor temperature sensor connected to the ERM, or the device is configured as a boiler. Connect an outdoor temperature sensor to the S1/S1 terminals. Note that the device only reports outdoor temperature when configured as a compressor.
What to do if the emergency backup control doesn’t function on my Honeywell Control Unit (if configured as boiler)?
If the emergency backup control doesn’t function (when configured as a boiler), the cause may be that there is no valid indoor temperature sensor. Check the sensor for a short circuit or open circuit, or install an indoor temperature sensor on the S1/S1 terminals.
What to do if no LEDs are on on my Honeywell Control Unit?
If no LEDs are on, it means there is no power to the device. Verify 24 VAC at the R/C terminals.
What to do if the connected LED is off on my Honeywell Control Unit?
If the connected LED is off, the device is not enrolled with the system. Enroll the device with the system.
Procedure to reset the ERM by holding the connect button for 10 seconds.
General| Brand | Honeywell |
|---|---|
| Model | ERM5220R1018 |
| Category | Control Unit |
| Language | English |
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