Error 45 in Hisense air conditioners

What error 45 is indicating on a Hisense air conditioner

Error 45 on a Hisense air conditioner is associated with an IPM fault (Intelligent Power Module) inside the inverter board/power board. In practical terms: the unit detects an abnormal condition in the power electronics that drive the compressor (power stage) and triggers a protection to prevent further damage.

Because it’s a power-protection fault, the system will usually show one of these symptoms:

• The fan starts, but the compressor doesn’t engage and the code appears
• It runs for a few seconds/minutes and then stops with the error
• The fault repeats as soon as it tries to demand cooling/heating

In most cases, the user doesn’t “repair” the IPM. What you can do is rule out external causes (reset, power supply, operating conditions) and confirm whether the error is a one-off event or persistent.

How to clear error 45 and what to check so it doesn’t come back

With error 45, the priority is to proceed in order: first do a full reset, then rule out unstable power and conditions that can trigger protections, and if it returns, move to service, because this involves power electronics.

1. Perform a complete electrical reset (a true power-off)
   • Turn the unit off with the remote
   • Cut power at the breaker/isolator for the AC
   • Wait 5–10 minutes and restore power
   • Try again in cooling or heating mode and see if 45 returns

   This step clears temporary control lockups after surges, brief outages, or failed starts.

2. Check the power supply before you keep trying
   • If there are micro-outages or voltage drops at home/premises, note it down
   • Avoid extension cords or shared outlets if your installation allows it
   • If the breaker trips or you notice erratic behavior on startup, don’t keep retrying in a loop
3. Review conditions that put extra load on the outdoor unit
   • Make sure the outdoor unit has good airflow and isn’t boxed in
   • Remove nearby obstructions and clean visible dirt from the grilles (without disassembly)
   • If it’s extremely hot outside, test at cooler times to see if the pattern changes

   A restricted outdoor unit or one working at the limit can trigger protections, although 45 typically points to the power stage.

4. Identify whether it’s a one-off or a constant fault
   • One-off: it clears after a reset and doesn’t return for days
   • Recurring: it comes back every time the compressor tries to start
   • Intermittent: it appears and disappears—often a component that fails under load or an inconsistent internal connection
5. When it makes sense to call service
   • Error 45 returns after a full reset and with stable power
   • It repeats whenever cooling/heating is demanded (compressor start)
   • There’s a burning electronics smell, unusual noises, or the unit protects immediately

   In those cases, troubleshooting typically focuses on the inverter board/driver board and the IPM itself (power electronics). This is a technical diagnosis: it requires measurements and, if needed, replacement of the module/board.

If 45 was a one-time event, it may be resolved with a full reset and proper operating conditions. If it comes back easily, the most efficient option is technical service to address the power electronics directly