2120
TROUBLESHOOTING GUIDE
SYMPTOM
Call Dealer For Service Light Flashing (see Figure M).
TROUBLESHOOTING PROCEDURE
Applies to both Automatic and Manual Operation unless
indicated otherwise.
Display Error Code: E1: RH Sensor
Rotate Humidifier Control knob to the “Test/Reset” position.
After 5 seconds, the green “Humidifier On” light will blink,
resetting the error. If E1 returns, replace the Humidifier Control.
Display Error Code: E2: Control Knob
Rotate Humidifier Control knob to the “Test/Reset” position.
After 5 seconds, the green “Humidifier On” light will blink,
resetting the error. If E2 returns, replace the Humidifier Control.
Display Error Code: E3: Outdoor Temperature Sensor
Auto Mode (switch in “AUTO” position)
1. Make sure that the Outdoor Temperature Sensor is properly
connected to the ODT terminals on the Humidifier Control.
2. Measure the resistance of the Outdoor Temperature Sensor
by removing the leads from the Humidifier Control terminals
and measuring the resistance across the wires with an
ohmmeter. Confirm the reading with the temperature in
Table 1 on page 22. Reconnect the ODT Sensor leads. If the
resistance value does not match the temperature value,
replace the Outdoor Temperature Sensor.
TROUBLESHOOTING PROCEDURE (CONTINUED)
3. Rotate Humidifier Control knob to the “Test/Reset” position.
After 5 seconds, the green “Humidifier On” light will blink,
resetting the error. If E3 returns, replace the Humidifier
Control.
Manual Mode (switch in “MAN” position)
1. Make sure the ODT terminals are clear of any wires that
may short the terminals together other than the ODT sensor.
2. Rotate Humidifier Control knob to the “Test/Reset” position.
After 5 seconds, the green “Humidifier On” light will blink,
resetting the error. If E3 returns, replace the Humidifier
Control.
Display Error Code: E4: Communication
This error applies to systems wired to an Aprilaire Model 8570
Thermostat (see Figure Q) using the “A” and “B” terminals.
Rotate the Humidifier Control knob to the “Test/Reset”
position. After 5 seconds, the green “Humidifier On” light will
blink, resetting the error. If E4 returns, check the wiring
between the Digital Humidifier Control and Model 8570 check
the connections at “A”and “B” on the humidifier control and
the Model 8570. Make sure the Model 8570 is wired and
operating properly according to the Model 8570 manual.
