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KeepRite · Heat pump

53 Outdoor air temperature sensor fault

Medium severity KeepRite *SA/*SH Single-Stage CommunicatingKeepRite *CA/*CH Two-Stage Communicating

What the control is telling you

The outdoor air thermistor reads open, shorted or out of range.

Applies to: KeepRite *SA5/*SA6 AC and *SH4/*SH5/*SH6 HP single-stage communicating; *CA7/*CA9 AC and *CH6/*CH9 HP two-stage communicating

Likely causes

  • Failed OAT thermistor
  • Wiring or connector fault

Test and repair steps

  1. Unplug the sensor and measure resistance against the resistance/temperature chart (about 16,000 ohms at 60°F).
  2. Check the harness and plug.
  3. Replace the sensor if out of range.

Models that show this code

11 models in KeepRite *SA/*SH Single-Stage Communicating, KeepRite *CA/*CH Two-Stage Communicating

*CH624*CH636*CH648*CH660*CH924*CH936*CH948*CH960*SH4*SH5*SH6

Other codes on the same units

  • 32 Low pressure switch open
  • 45 Outdoor control board failure
  • 46 Brown-out (low voltage)
  • 47 No 230 V at the unit
  • 55 Outdoor coil sensor fault
  • 56 Air and coil sensors disagree
  • 71 Low stage thermal cutout
  • 72 Compressor thermal cutout (two-stage: high stage)

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Source: KeepRite/ICP C4A3/H4A3/T4A3/CXA6 Installation Instructions 421 01 5103 05, Table 1 Status Codes, p.17; KeepRite_ICP_KeepRite_Tempstar_Heil_split_A_C_HP_R_410A_R_22_service_421_08_5400_04.txt - section Table 13 Status Codes (single-stage); 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.