Rheem
Unstable Control Signal or Relay Chatter
Thermostat clicks or relays chatter repeatedly without the HVAC equipment starting properly.
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Safety Warning
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.
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Possible Causes
Low or fluctuating 24VAC supply, Shorted thermostat wiring, Failing relay driver in thermostat, Loose sub-base connection
How to Fix / Troubleshooting
Steps:
- Measure voltage: Monitor 24VAC between R and C at the thermostat while the system attempts to start. Large drops indicate a supply issue.
- Inspect wiring for shorts: Look for any thermostat wires with damaged insulation touching each other or metal.
- Reseat thermostat: Remove and firmly reattach the thermostat to ensure good contact with the sub-base pins.
- Check indoor unit fuse: Replace a blown fuse only after correcting any wiring faults.
- If voltage is stable but chatter continues: The thermostat's internal relays or drivers may be failing; replace the thermostat.
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Repair Difficulty
Medium
3/5
Required Part
Thermostat Relay Driver Circuit
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