Friedrich racservmn Service Manual page 40

Troubleshooting: Heating
PROBLEM
No heating — fan
operates.
PROBLEM
Insufficient heating.
PROBLEM
Fan operates in
"constant" position, but
not in "automatic"
(MoneySaver).
PROBLEM
Temperature varies from
comfortable to overly
warm.
PROBLEM
Room temperature
uneven.
(Heating cycle)
PROBLEM
Unit will not defrost.
40
(Heat pumps)
POSSIBLE CAUSE
Thermostat setting.
Defective thermostat.
Compressor not operating.
Defective system switch.
POSSIBLE CAUSE
Restricted filter.
Outdoor thermostat.
(Applicable models.)
Fresh air or exhaust door open.
POSSIBLE CAUSE
Inoperative system switch.
Incorrect wiring.
POSSIBLE CAUSE
Defective thermostat.
Heat anticipator (resistor) shorted.
(Applicable models)
POSSIBLE CAUSE
Heat anticipator (resistor) shorted.
(Applicable models.)
Wide differential — partial loss of ther-
mostat bulb charge.
Incorrect wiring.
POSSIBLE CAUSE
Incorrect wiring.
Defrost control timer motor not advanc-
ing.
Defrost control out of calibration.
Defrost control contacts stuck.
Defrost control bulb removed from coil,
or not making good coil contact.
TO CORRECT
Set thermostat to a warmer position.
Replace — do not attempt to adjust.
Check compressor wiring. Check for open internal
or external overload. Check wiring.
Test system switch
TO CORRECT
Clean as recommended in Owner's Manual.
Check if outdoor thermostat is energizing the heating
element at its predetermined temperature setting
Check control setting.
TO CORRECT
Check continuity of switch.
Check applicable wiring diagram.
TO CORRECT
Incorrect differential setting. Replace thermostat.
Check voltage to resistor. If voltage okay, remove
resistor from thermostat bulb block. With current on,
feel resistor for warmth. If no heat can be felt,
replace anticipator.
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.
Refer to appropriate wiring diagram. Resistor is
energized during the "on" cycle of compressor or
fan.
TO CORRECT
Refer to appropriate wiring diagram.
Check for voltage at "TM" and "TM1" on timer. If
voltage, replace control.
If outside coil temperature is 25° F or below, and
preselected time limit has elapsed, replace the
defrost control.
If the contacts remain closed between terminals "2"
and "3" of the defrost control after preselected time
interval has passed, replace control.
Reinstall and assure that good bulb to coil contact is
made.