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Grant Aerona R32 fault U1

Compressor overheat protection relay operation (HPID13R32 & HPID17R32)

Heat pump

What it means

Compressor overheat protection relay has tripped, potentially due to relay failure or refrigerant gas leakage.

Likely causes

  1. Blown compressor overheat protection relay
  2. Gas leakage in refrigerant circuit
  3. Thermal store set point reached (normal stop)
  4. Outgoing water temperature reaching protection limit (abnormal/protective stop)

Where to start

  1. Check the resistance of compressor overheat protection relay by tester
  2. Check the service valve and refrigerant circuit (pipe)
  3. Verify pump activates for Time ON period set by Parameter 4201

The full answer, free

  • 16 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 57), right under the answer
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Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Grant manual for the Aerona R32. Check the model on the data plate before you order parts.

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