Lennox Error Code E440: Inverter compressor slowdown – high heat-sink temperature (inverter code 13) (Heat Pump)
Lennox error code E440 on a heat pump means: Inverter compressor slowdown - high heat-sink temperature (inverter code 13). It is also called Lennox diagnostic code E440.
Homeowner? What Lennox code E440 means for you
Usually minor Your heat pump is reporting: Inverter compressor slowdown - high heat-sink temperature (inverter code 13). This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Check both breakers and the outdoor disconnect box beside the outdoor unit; all should be ON.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- In winter, keep snow and ice off and away from the outdoor unit. A short defrost cycle with steam is normal.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Lennox error code E440 mean?
Heat sink near its limit; the compressor slows (about 4 Hz, 5-6%) to cool it. Speed reduction starts above 185 F and full speed resumes at 176 F. Normal for 3-4 minutes above 110 F outdoor (dealer information). Inverter LED flash code 13 (red 1 flash, green 3 flashes). S30/S40 thermostat alert code 440 (shown as E440 on the unit control display).
Applies to: Lennox communicating heat pumps incl. variable-capacity inverter units in S30/S40 smart thermostat systems
Common causes of Lennox code E440
- High outdoor temperature
- Debris on heat sink
- Loose heat sink screws
Lennox models that use code E440
EL16KP1-018EL16KP1-024EL16KP1-030EL16KP1-036EL16KP1-042EL16KP1-048EL16KP1-060ML14KP1-018ML14KP1-024ML14KP1-030ML14KP1-036ML14KP1-042ML14KP1-048ML14KP1-060
Other Lennox Heat Pump codes
All Lennox Heat Pump error codes →
Lennox code E440: homeowner questions
What does Lennox code E440 mean?
Inverter compressor slowdown - high heat-sink temperature (inverter code 13). Heat sink near its limit; the compressor slows (about 4 Hz, 5-6%) to cool it. Speed reduction starts above 185 F and full speed resumes at 176 F. Normal for 3-4 minutes above 110 F outdoor (dealer information). Inverter LED flash code 13…
Is it safe to keep using my heat pump with code E440?
Usually yes. Code E440 is normally minor, but if it keeps coming back have it checked.
Can I reset Lennox code E440 myself?
You can try one reset (power off for 30 seconds, then on). If Lennox code E440 comes back, the cause is still there and a licensed technician should check it.
Who can fix Lennox code E440 near me?
Aurora Star Tech Inc. repairs Lennox heat pumps in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: AC Running But Not Cooling: What to Check · Heat Pump Not Heating or Blowing Cold Air
Troubleshooting guides
- Heat pump not defrosting / outdoor coil iced - Lennox EL16KP1 / ML14KP1 Lennox · Heat Pump
- Low capacity or abnormal pressures - Lennox EL16KP1 / ML14KP1 Lennox · Heat Pump
- Outdoor unit will not start - Lennox EL16KP1 / ML14KP1 Lennox · Heat Pump
- Two horizontal lines on display (soft disable) - Lennox communicating Lennox · Heat Pump
Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.42. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.