Lennox MS8 SERIES Installation And Service Procedures page 41

HEAT MODE (I FEEL MODE ON)
Heat Mode - Indoor temperature set point range is 61°F and 86°F (16°C and 30°C)
NOTE — Reversing valve is energized in heating mode.
Delays that normally protect the compressor are disabled during defrost cycles:
1. Minimum three (3) minute compressor time delay between operating cycles.
2. Minimum six (6) minute compressor run time between operating cycles.
If room ambient temperature is equal to or less than the remote control setpoint - 1.8°F (1°C) the unit cycles heating ON. If it
has been 3 minutes since the last heating demand, the compressor and outdoor fan motor will cycle ON. The indoor fan will
operate according to the Cold Blow Prevention function.
If room temperature is equal to or greater than remote control setpoint + 1.8°F (1 °C ), the compressor will cycle OFF. The
outdoor fan will cycle OFF 30 seconds later. The indoor fan will operate for 60 seconds after heating cycles OFF.
The fan speed is determined by the difference between the room ambient temperature and the remote set point temperature.
The system prevents cold air from blowing into space during heating operation. After three (3) minute time delay, one of the
following indoor fan cycles will occur:
* If the indoor ambient temperature is greater than 75ºF (24ºC): If the coil temperature is equal to or greater than 104ºF
(40ºC) the indoor fan will run at low speed for 1 to 2 minutes. If during that time the coil temperature rises above 106ºF
(42ºC), the indoor fan will ramp to a preprogrammed heat speed for those conditions.
* If the indoor ambient temperature is less than 75ºF (24ºC): If the coil temperature is equal to or greater than 106ºF (42ºC)
the indoor fan will run at low speed and within one minute, the indoor fan will ramp to preprogrammed heat speed for
those conditions.
The reversing valve is energized in heating and will stay energized for 2 minutes after the compressor is de-energized. The
reversing valve is energized 2 seconds before the compressor is energized.
HEATING MODE
FIGURE 57
Protective Functions
Heat ON
Heat OFF
Indoor Fan Operation - Heating
Cold Blow Prevention
Reversing Valve Operation
Page 41
Corp. 1244-L9