81 Low stage thermal lockout

What the control is telling you

Thermal cutout on 3 cycles in a row; low stage locked out 4 hours or until 24 V is cycled.

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

Likely causes

• Repeated low-stage overload trips - see code 71

Test and repair steps

1. Fix the code 71 cause.
2. Cycle 24 V to clear.

Models that show this code

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

Other codes on the same units

• 56 Air and coil sensors disagree
• 71 Low stage thermal cutout
• 72 Compressor thermal cutout (two-stage: high stage)
• 73 Contactor stuck closed
• 74 No 230 V at compressor
• 82 Thermal lockout (two-stage: high stage)
• 83 Low pressure lockout
• 84 High pressure lockout