Raypak controller shows Er4; unit will not heat.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Failed evaporator coil sensor, Sensor not attached to coil, Wiring harness damage, Control board fault

Safety first: Disconnect power before opening the unit.

Find coil sensor: Locate the sensor clipped to the evaporator coil. Ensure it is firmly attached and making good contact with the tubing.
Inspect wiring: Check for corrosion or damage along the sensor lead. Reseat the connector at the board.
Test sensor: Measure resistance and compare to Raypak specifications. Replace if out of range.
Replace sensor: Clip the new sensor securely to the coil in the same location and route the wire away from sharp edges.

Hard 4/5

Evaporator Coil Temperature Sensor

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