Grant Aerona R290 fault E34

AC input voltage is abnormal

Heat pump

What it means

AC input voltage supplied to the unit is outside expected range.

Likely causes

  1. Cables incorrectly connected
  2. Refrigerant & Drive PCB is faulty
  3. Fuse is burnt out
  4. Connection to PCB is loose or disconnects
  5. Pump failure
  6. Too low voltage
  7. Pump rotors are stuck

Where to start

  1. Check all connections from the Refrigerant PCB (or Refrigerant & Drive PCB for the 16kW model)
  2. Check fuse condition
  3. Check pump connection to Hydraulic PCB

The full answer, free

  • 12 more checks in order
  • How to put it right, step by step
  • The manual page for this fault (page 61), right under the answer

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 R290. Check the model on the data plate before you order parts.

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