Carrier Error Code 74: Discharge temperature lockout (Heat Pump)
Carrier error code 74 on a heat pump means: Discharge temperature lockout. It is also called Carrier diagnostic code 74.
Homeowner? What Carrier code 74 means for you
Call a technician Your heat pump is reporting: Discharge temperature lockout. The heat pump has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
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 Carrier error code 74 mean?
Amber STATUS light flashes 74. Discharge temperature kept going over the limit (elevated from code 59). The unit locks out for 2 hours. Type: System malfunction; reset: 2 hours.
Applies to: Carrier Infinity 18VS variable speed heat pump 25VNA8 (AOC control + inverter)
Common causes of Carrier code 74
- Cooling: High load or overcharge
- Heating: Low charge or loss of charge at low outdoor temperature
- Heating: EXV restriction or EXV / TXV problem
A technician checks these and 5 other possible causes on site before replacing any part.
Carrier models that use code 74
25VNA81325VNA82425VNA82525VNA83625VNA83725VNA84825VNA860
Other Carrier Heat Pump codes
All Carrier Heat Pump error codes →
Carrier code 74: homeowner questions
What does Carrier code 74 mean?
Discharge temperature lockout. Amber STATUS light flashes 74. Discharge temperature kept going over the limit (elevated from code 59). The unit locks out for 2 hours. Type: System malfunction; reset: 2 hours.
Is it safe to keep using my heat pump with code 74?
It depends on the cause. The heat pump has locked out or cannot run properly. One reset is fine; if the code comes back, it needs a licensed technician to find the cause.
Can I reset Carrier code 74 myself?
You can try one reset (power off for 30 seconds, then on). If Carrier code 74 comes back, the cause is still there and a licensed technician should check it.
Who can fix Carrier code 74 near me?
Aurora Star Tech Inc. repairs Carrier 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
- Amber STATUS or green COMM light not on Carrier · Heat Pump
- Delay before the compressor restarts Carrier · Heat Pump
- Heat pump will not defrost - HK32EA defrost board Carrier · Heat Pump
- Noisy compressor or loud defrost shift - Carrier split systems Carrier · Heat Pump
- Outdoor ECM fan not running - Carrier 25HNB9/24ANB1 Carrier · Heat Pump
- Outdoor unit unresponsive after several faults Carrier · Heat Pump
- Outdoor unit will not run - HK32EA defrost board heat pumps Carrier · Heat Pump
Source: Carrier 25VNA8 / 24VNA9 Service Manual, Table 6 Fault Code Actions, p.22. 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.