Heat Pump Inverter Failure — Ship It, We Fix It
A faulty heat pump inverter in winter means no heating for your building. A new Danfoss VLT AQUA Drive costs €1,200–3,800. An ABB ACS850 replacement: €1,500–4,200. OEM Daikin or Mitsubishi inverter boards: €800–2,500 from the manufacturer, with weeks of lead time. Our component-level PCB repair costs €280–750 and takes 2–5 working days.
Customers from London, Paris, Amsterdam, Brussels, Vienna, Munich, Zurich, Stockholm, Copenhagen, Oslo, Milan, Rome, Madrid, Barcelona, Prague, Warsaw, Budapest, and Bucharest ship us heat pump inverter boards and complete drive units regularly. The module is typically 2–5 kg and fits in a standard DHL parcel.
Danfoss VLT AQUA / HVAC Drive Repair
Danfoss VLT series drives are installed in millions of HVAC systems across Europe. Common faults:
- Warning/Alarm 29 (Power board fault) — IGBT gate drive desaturation fault; one gate drive optocoupler (HCPL-316J or equivalent) failure. We replace the individual IC — not the entire power card (OEM price: €650–1,200).
- Warning/Alarm 9 (Inverter overloaded) — false trip due to current sensor (LEM LTS/LAS) drift after 6–10 years; zero-offset calibration IC failure on the power card.
- Warning/Alarm 38 (Internal fault) — EEPROM on the LCP control panel corrupted after power surge; we reflash the LCP without losing parameter set.
- Warning/Alarm 27 (Brake chopper fault) — braking IGBT module failure; common when external brake resistor has been incorrectly sized or disconnected under load.
- DC bus capacitor bank failure — audible 100Hz ripple, alarm 5 (DC link voltage low on deceleration); we replace the full capacitor bank using matched Nippon Chemi-Con or Nichicon series.
- Fan control board fault — drive overtemperature despite ambient being within spec; fan controller MOSFET failure causing cooling fan to stop. Common on VLT AQUA FC202 in pump rooms.
ABB ACS550 / ACS850 / ACS880 Repair
- Fault 0022 (Parameter change fault) — flash memory IC failure on the main control board after power loss during parameter write; we replace the NOR flash and restore factory defaults, then customer re-enters parameters.
- Fault 0001 (Overcurrent) — IGBT module output bridge failure; we source matching Infineon or ABB IGBTs and rebuild the output bridge including snubber networks.
- Fault 0002 (DC overvoltage) — braking chopper IGBT or the braking resistor driver fault; commonly triggered when pump system back-pressure exceeds motor regenerative threshold.
- Supply unit fault (ACS880 LSU) — active front-end IGBT failure in the regenerative supply unit; complex repair involving matched IGBT sets and gate driver board replacement.
- I/O extension module fault — FIO-01, RAIO-01 I/O option module communication fault; CAN/DDCS interface IC failure. We repair the option module rather than replacing it (OEM: €280–650).
Daikin / Mitsubishi Heavy / Hitachi HVAC Inverter Board Repair
Japanese brand HVAC systems dominate commercial buildings across Southern and Western Europe:
- Daikin error U4 (Signal transmission error) — inverter-to-outdoor-unit communication IC failure; RS-485 transceiver replacement. Common on Daikin VRV IV and VRVX systems.
- Daikin error E7 (Fan motor lock) — IPM (Intelligent Power Module) failure on the outdoor fan inverter board; we replace the IPM IGBT with Mitsubishi PS21865 or equivalent and requalify.
- Mitsubishi Heavy error 6607 (Inverter overcurrent) — gate drive bootstrap capacitor failure on compressor inverter board causing IGBT shoot-through.
- Hitachi error [02] (Compressor overcurrent) — DC bus shunt resistor drift causing false overcurrent trip; current sense resistor replacement and calibration.
Pricing and Service Details
Danfoss VLT power card repair: €280–680. Control card repair: €180–380. ABB ACS550/ACS850 main board: €320–720. ACS880 supply unit IGBT repair: €480–950. Daikin/Mitsubishi Heavy inverter board: €220–580. DC bus capacitor bank replacement: €180–420. Return courier to Western EU: included. Return to Eastern EU, UK, Scandinavia: €35–55 supplement. Turnaround: 2–5 working days. Priority 48h service available. 12-month warranty.