KeepRite · Air conditioner

53 Outdoor air temperature sensor fault

Medium severity KeepRite C4A3/CXA6 ACKeepRite *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 C4A3/CXA6 AC with outdoor control board; *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

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

Settings for these units

Outdoor unit clearances · KeepRite C4A3/CXA6 AC

Location	Minimum
Service end	24 in. (610 mm)
Above unit	48 in. (1219 mm)
One side	6 in. (152 mm)
Other sides	12 in. (305 mm)
Between units	24 in. (610 mm); 18 in. (457 mm) with no overhang within 12 ft
Roof mount height above roof	6 in. (152 mm)
Shrubs/fences from coil	18 in. (457 mm)

Keep roof run-off and snow from falling on the unit.

Unit must be level within 2 degrees.

Models that show this code

12 models in KeepRite C4A3/CXA6 AC, KeepRite *SA/*SH Single-Stage Communicating, KeepRite *CA/*CH Two-Stage Communicating

*CA624*CA636*CA648*CA660*CA924*CA936*CA948*CA960*SA5*SA6C4A3CXA6

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.