R - A 10
Alert Code Response
Error 90: Communication busy fault
Comfort Control = Err 90
User Interface = SYS COMM ERR and/or SYS COMM CRC
Air Handler Fault LED = 3 Flash
or
Furnace Fault LED = 10 Flash
or
Outdoor Unit Fault LED = 1 Flash
Problem Description
• Excessive communication errors
- Comfort control is continually attempting to
communicate with no idle detected (bus busy)
Possible Causes/Solutions
• R and B wiring reversed at comfort control or indoor unit
• Telephone Access Module (TAM) out of sequence
- Disconnect TAM and recycle power, if error clears,
replace the TAM
Error 90: Communication busy fault
Comfort Control = Err 90
User Interface = No Alert Displayed
Fault LED = No Fault Reported by Indoor or Outdoor Unit
Problem Description
• Excessive communication errors
- Comfort control is continually attempting to
communicate with no idle detected (bus busy)
Possible Causes/Solutions
• Faulty field control wiring to comfort control
• Telephone Access Module (TAM) out of sequence
- Disconnect TAM and recycle power, if error clears,
replace the TAM
• If error does not clear contact your local field rep for
additional support
Error 91: Communication fault
Comfort Control = Err 91
User Interface = NO SYS CLK
Air Handler Fault LED = 3 Flash
or
Furnace Fault LED = 10 Flash
Problem Description
• System clock is not reporting
- Bit Master LED will be off
Possible Causes/Solutions
• Replace indoor control board
• Failure could be caused by voltage spikes or
electrostatic discharge
Error 89: Equipment missing
Comfort Control = Err 89
User Interface = No Alert Displayed
Outdoor Fault LED = No Fault Reported
Problem Description
• Equipment that was auto discovered at start-up is
no longer reporting
- When communicating systems are initially powered
the comfort control will auto discover and remember
all equipment (outdoor unit, indoor unit, and each bank
of electric heat) reported on the communication bus
Possible Causes/Solutions
• Outdoor unit breaker tripped
• OD transformer or fuse open
• Field control wiring to outdoor unit is open
- 16vDC between D & B at outdoor unit indicates the
OD unit is not communicating
• Auto discovered aux heat circuit(s) no longer sensed
- Contactor coil, thermal limit or connection to control
board may be open
• ERR89 may be followed by an ERR79, ERR53 or
ERR126 depending on when the error occurred
To Next Page
Loading...
