Lennox MS8 SERIES Installation And Service Procedures page 73

Poor system performance.
Incorrect temperature setting.
Load demand is greater than
system capacity.
Refrigerant flow
issue.
Possible heat loss due to poor line
set insulation.
Insufficient air
flow
Outdoor air temperature is too high
POOR SYSTEM OPERATION (ALL SIZES)
Adjust temperature set point.
Check heating or cooling load calculations.
Low refrigerant due to leak.
Internal compressor high or low
pressure leak.
Reversing valve malfunction (heat
pump only).
Possible refrigerant flow
restriction.
Verify line set is properly insulated. If insulation is
missing then repair.
Block indoor or outdoor coil.
Air filter blocked.
Indoor fan speed set to low.
Fan speed is not constant. or
running at lower speed that
configured.
Improper outdoor unit installation.
Recommend installing a field-proved cover over the the
outdoor unit. If cover does not resolve problem, then a higher
capacity system may be required. Replace system.
FIGURE 84
Page 73
Repair leak, check refrigerant
charge and adjust accordingly.
Replace compressor.
Replace reversing valve
Locate source of restriction and correct.
Clean indoor or outdoor coil.
Clean or replace air filters
Set fan speed to middle or high speed.
Damage
Replace capacitor.
capacitor
Fan motor
Replace fan motor.
damaged
Proper ventilation around outdoor unit is
required for correct unit operation.
Reposition unit to required clearances.
Corp. 1244-L9