Friedrich 2009, 2008 service manual Problem, Possible Cause, Action

HEAT / COOL ONLY ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS

Problem	Possible Cause	Action
	Heat anticipator (resistor) shorted (on applicable	Disconnect power to unit. Remove resistor from
		t-stat bulb block. Plus in unit & allow to operate.
	models)
		Feel resistor for heat. If not heat, replace resistor
Room temperature
uneven	Wide differential - partial loss of t-stat bulb charge	Replace t-stat & check
(Heating cycle)
		Refer to appropriate wiring diagram. Resistor is
	Incorrect wiring	energized during "ON" cycle of compressor or
		fan.

Problem	Possible Cause	Action
	Incorrect wiring	Refer to appropriate wiring diagram
	Defrost control timer motor not advancing	Check for voltage at "TM" & "TM1" on timer. If no
	(applicable models)	voltage, replace control
	Defrost control out of calibration (applicable	If outside coil temperature is 25F or below, &
		preselected time limit has elapsed, replace
	models)
Unit will not defrost		defrost control
		If contacts remain closed between terminals "2"
	Defrost control contacts stuck	& "3" of the defrost control after preselected time
		interval has passed, replace control
	Defrost control bulb removed from or not making	Reinstall & be assured that good bulb to coil
	good coil contact	contact is made

Problem	Possible Cause	Action
	Exhaust or fresh air door open	Check if operating properly. Instruct customer on
		proper use of control
	Dirty filter	Clean as recommended in Owner's Manual
		Check heat rise across coil. If unit operates
	Unit undersized	efficiently, check if insulation can be added
		to attic or walls. If insulation is adequate,
Does not heat		recommend additional unit or larger one
adequately		T-stat should close at 38°F. Check continuity of
	Outdoor t-stat open (applicable models)	control. If temperature is below 38°F, replace
		control
	Heater hi-limit control cycling on & off	Check for adequate fan air across heater. Check
		control for open at 160°F & close at 150°F
	Shorted supplementary heater	Ohmmeter check, approx. 32-35 ohms
	Incorrect wiring	Check applicable wiring diagram

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