Comfortmaker indoor display shows E3 and outdoor unit does not start or shuts down quickly

Safety: Turn off the outdoor condenser disconnect and indoor breaker. Verify the contactor is not energized before working.

Steps:

• Remove condenser top or side panel: Access the control compartment and coil area of the Comfortmaker outdoor unit.
• Locate the outdoor coil sensor: Typically clipped to the condenser coil tubing or mounted near the coil with two small wires going to the outdoor PCB.
• Inspect sensor and wiring: Look for physical damage, corrosion, rodent damage, or pulled wires. Repair any damaged wiring and secure with cable ties.
• Check connector at PCB: Unplug and replug the sensor connector to ensure a solid connection.
• Test resistance: With power off, measure sensor resistance and compare to the Comfortmaker thermistor chart. Replace if open, shorted, or out of range.
• Replace sensor if needed: Install a compatible Comfortmaker/ICP outdoor coil sensor, routing wires away from sharp edges and hot discharge lines.
• Restore power and test: Reinstall panels, turn power back on, and run the system. Confirm E3 does not return.

Technician recommended: If the sensor is good but E3 persists, the outdoor control board may need replacement and should be evaluated by an HVAC technician.