Viessmann AirflowPLUS AH2A-213 Installation, Service And Operating Instruction page 45

Viessmann AirflowPLUS AH2A Installation, Operating and Service
Troubleshooting
The air handler internal water coil
freeze sensor T3 is activated
by low air temperature.
Housing mounted LED
is illuminated.
Internal pump and circulation
fan running at high speed for
5 minutes, A/C compressor
is disabled for 5 minutes.
Cooling cycle restarts after
5 minute delay
The air handler internal water coil
freeze sensor T3 is activated
by low air temperature.
Check for poor air flow,
restrictions, plugged filters,
low refrigerant charge
3 protect cycles occur in a single
cooling cycle, cooling cycle is
inhibited, sensor T3 indicates 7
green-7 green, alarm buzzer ON .
(continued)
Yes
Yes
Yes
Yes
Continue
Continue
Yes
Refer to cooling lockout chart.
Water coil freeze protection
This sequence is initiated by extreme low air temperatures
crossing over the freeze protection sensor located directly
above the air handler water coil.
Yes
Service
45