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KeepRite · Air conditioner

71 Low stage thermal cutout

High severity KeepRite *CA/*CH Two-Stage Communicating

What the control is telling you

Compressor ran on low stage, then disappeared while low-stage demand remained.

Applies to: KeepRite *CA7/*CA9 AC and *CH6/*CH9 HP two-stage communicating

Likely causes

  • Compressor internal overload trip
  • Start relay/capacitor left in circuit too long

Test and repair steps

  1. Check voltage and contactor.
  2. Check windings once cool (see two-stage resistance table).
  3. Check start components if fitted.

Settings for these units

Models that show this code

8 models in KeepRite *CA/*CH Two-Stage Communicating

*CA624*CA636*CA648*CA660*CA924*CA936*CA948*CA960

Other codes on the same units

  • 47 No 230 V at the unit
  • 53 Outdoor air temperature sensor fault
  • 55 Outdoor coil sensor fault
  • 56 Air and coil sensors disagree
  • 72 Compressor thermal cutout (two-stage: high stage)
  • 73 Contactor stuck closed
  • 74 No 230 V at compressor
  • 81 Low stage thermal lockout

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Source: KeepRite_ICP_KeepRite_Tempstar_Heil_split_A_C_HP_R_410A_R_22_service_421_08_5400_04.txt - section Table 17 Troubleshooting (two-stage). Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.