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Unit does not heat
adequately.
Outdoor thermostat does not cut off
compressor at the preselected tem-
perature and bring on heating element.
Fresh air or exhaust door open.
Dirty filter.
Unit undersized.
Defective thermostat - replace.
Check if operating properly. Instruct customer
on proper use of control.
Clean as recommended in Owner’s Manual.
Check heat rise across coil. Refer to perfor-
mance data sheet on heat rise at various
outdoor ambients. If heat rise is satisfactory,
check if insulation can be added to attic or
walls.
PROBLEM POSSIBLE CAUSE TO CORRECT
Refer to applicable wiring diagram.
Check for continuity of coil.
Block condenser coil and switch unit to cooling.
Allow pressure to build up in system, then
switch to heating. If valve fails to shift, replace
valve.
Check for continuity of system switch.
Unit cools when
heat is called for.
Incorrect wiring.
Defective solenoid coil.
Reversing valve fails to shift.
Inoperative system switch.
PROBLEM POSSIBLE CAUSE TO CORRECT
TO CORRECT
Defective thermostat — replace.
Check if operating properly. Instruct customer on
proper use of control.
Clean as recommended in Owner’s Manual
Check heat rise across coil. Refer to performance
data sheet on heat rise at various outdoor ambients. If
heat rise is satisfactory, check if insulation can be
added to attic or walls.
POSSIBLE CAUSE
PROBLEM
Outdoor thermostat does not cut off
compressor at the preselected tempera-
ture and bring on the heating element.
Fresh air or exhaust door open.
Dirty filter.
Unit undersized.
Unit does not heat
adequately.
TO CORRECT
Refer to applicable wiring diagram.
Check for continuity of coil.
Block condenser coil and switch unit to cooling. Allow
pressure to build up in the system, then switch to
heating. If valve fails to shift, replace valve.
Check for continuity of system switch.
Incorrect wiring.
Defective solenoid coil.
Reversing valve fails to shift.
Inoperative system switch.
POSSIBLE CAUSEPROBLEM
Unit cools when
heat is called for.
TO CORRECT
Check for partially starved outer coil. Replace heating
capillary tube.
Switch unit several times from heating to cooling.
Check temperature rise across the coil. Refer to
specification sheet for correct temperature rise.
Deenergize solenoid coil, raise head pressure, ener-
gize solenoid to break loose. If valve fails to make
complete shift, replace valve.
POSSIBLE CAUSE
PROBLEM
Heating capillary tube partially
restricted.
Check valve leaking internally.
Reversing valve failing to shift
completely — bypassing hot gas.
Cooling is ad-
equate, but heating
is insufficient.