Friedrich KQ08J50A-B Service & Parts Manual page 30

PROBLEM
Unit does not heat
adequately.
PROBLEM
Unit cools when heat
is called for.
PROBLEM
Cooling adequate
—heating insufficient.
PROBLEM
Compressor will not turn
off and operate on heat-
ing element only during
low outside ambients.
PROBLEM
Compressor shuts
off on outdoor
thermostat but
element does
not heat.
Page 30
POSSIBLE CAUSE
Outdoor thermostat does not cut
off compressor at the pre-selected
temperature and bring on the heating
element.
Fresh air or exhaust door open.
Dirty filter.
Unit undersized.
POSSIBLE CAUSE
Incorrect wiring.
Defective solenoid coil.
Reversing valve fails to shift.
Inoperative system switch.
POSSIBLE CAUSE
Heating capillary tube partially re-
stricted.
Check valve leaking internally.
Reversing valve failing to shift com-
pletely — bypassing hot gas.
POSSIBLE CAUSE
Outdoor thermostat.
(Applicable models.)
POSSIBLE CAUSE
Fuse link.
Heating element shorted.
Incorrect wiring.
Heat relay or heater contactor coil
open.
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.
TO CORRECT
Refer to applicable wiring diagram.
Check for continuity of coil.
Block condenser coil and switch unit to cooling. Al-
low pressure to build up in the system, then switch to
heating. If valve fails to shift, replace valve.
Check for continuity of system switch.
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.
De-energize solenoid coil, raise head pressure, en-
ergize solenoid to break loose. If valve fails to make
complete shift, replace valve.
TO CORRECT
Refer to the heating data on applicable models for
the pre-selected temperature the compressor shuts
off and the electric element is energized.
TO CORRECT
Check fuse link for continuity. If defective, replace.
Check amperage draw of element. If no amperage,
replace.
Check voltage to element. If voltage is okay, check
wiring.
Defective coil. Test coil for continuity.