Error code reference

Aprilaire HVAC Error Code E5

High Temperature Sensor Thermistor Failure: the signal from the High Temperature Sensor is open or shorted, most likely due to a loose connection at the Internal Control board or a failed sensor.

SourceAprilaire Dehumidifier - Service Manual: Models 1830 & 1850p. 7

Aprilaire codes Aprilaire hvac codes

Diagnostic procedure

The full E5 procedure

Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Turn the ON/OFF toggle switch OFF, remove side panel, insulation and electrical box cover, remove connector for the High Temperature Sensor and measure resistance across the terminals.

SourceAprilaire Dehumidifier - Service Manual: Models 1830 & 1850p. 7

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More steps, wiring diagram references, and verified part numbers

Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.

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Where this code is documented

2 manuals in the MyPros+ library document this code for Aprilaire hvac.

Models covered by the manuals that document this code

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The full E5 procedure

Where this code is documented

Models covered by the manuals that document this code

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