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KeepRite · Heat pump

16 Lost communication with wall control

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

What the control is telling you

The outdoor board no longer hears the communicating wall control.

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

  • Loose or broken DX+/DX-/C/R wiring
  • Wall control or indoor unit without power

Test and repair steps

  1. Check the 4-wire connections at the wall control, indoor and outdoor units.
  2. Confirm the indoor unit and wall control have power.
  3. Watch the green COMM light it comes on steady once valid messages arrive and goes out if none arrive for 2 minutes.

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

  • 25 Model plug missing or invalid
  • 31 High pressure switch open
  • 32 Low pressure switch open
  • 45 Outdoor control board failure
  • 46 Brown-out (low voltage)
  • 47 No 230 V at the unit
  • 53 Outdoor air temperature sensor fault
  • 55 Outdoor coil sensor fault

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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.