Troubleshooting Heating (Cooling/Electric Models) - Friedrich KQ08J50A-B Service & Parts Manual

Troubleshooting Heating
(Cooling/Electric Models)
PROBLEM
Fan Operates
– heating element
does not come on.
PROBLEM
Heating inadequate.
PROBLEM
Fan operates in
"Constant" position,
but not in "Automatic"
(MoneySaver).
PROBLEM
Long "off" and
"on" cycles.
POSSIBLE CAUSE
Heater relay or contactor coil open.
Heater relay or contactor stuck open,
pitted or burned.
High limit control open.
Open thermal fuse.
Open or shorted element.
Loose connections.
POSSIBLE CAUSE
Restricted filter.
Cycling high limit control.
Exhaust or fresh air door open.
POSSIBLE CAUSE
Fan relay contacts open.
Inoperative system switch.
Loose connection.
POSSIBLE CAUSE
Heat anticipator (resistor) shorted.
Defective thermostat.
TO CORRECT
Check continuity of coil.
Inspect, test continuity with ohmmeter.
Check continuity – if open, replace.
Check continuity. Check reason for failure.
Check voltage across heater terminals. Check
amperage draw of heater.
Tighten all terminals.
TO CORRECT
Clean as recommended in Owner's Manual.
Control is set to open at 155°F ± 5°F and close
at 130°F ± 8°F. If cycling prematurely, replace
control.
Check position of fresh air door control slide.
Adjust cable if door does not close properly.
TO CORRECT
Check continuity of fan relay. NOTE: Some
models have the fan relay energized during the
heating cycle while others do not.
Check continuity between terminals "L2" and "3"
of the system switch.
Check connections on system switch and fan
relay.
TO CORRECT
Disconnect power to unit. Remove resistor from
thermostat bulb block. Plug in unit and allow to
operate. Feel resistor for heat. If no heat is felt,
replace resistor.
Replace thermostat and check operation.
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