Friedrich R-410A service manual Problem, Possible Cause, Action

COOLING ONLY ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS

Problem	Possible Cause	Action
		Replace fuse, reset breaker. If repeats, check
	Fuse blown or circuit tripped	fuse or breaker size. Check for shorts in unit
		wiring & components
	Power cord not plugged in	Plug it in
Unit does not run	System switch in “OFF” position	Set switch correctly
	Inoperative system switch or open	Test for continuity
	electronic control board
	Loose or disconnected wiring at	Check wiring & connections. Reconnect per
	switch, control board or other com-
		wiring diagram
	ponents

Problem	Possible Cause	Action
	Dirty filter	Clean as recommended in Owner’s Manual
		Check for dirty or obstructed coil. Use
	Restricted airflow	pressure wash or biodegradable cleaning
		agent to clean
Evaporator coil	Inoperative t-stat or thermistors	Test for continuity
freezes up	Short of refrigerant	De-ice coil & check for leak
	Inoperative fan motor	Test fan motor & replace if inoperative
		De-ice coil. Check temp. differential (delta T)
	Partially restricted capillary tube	across coil. Touch test coil return bends for
		same temp. Test for low running current

Problem	Possible Cause	Action
	Excessive heat load	Unit undersized. Test cooling performance &
		replace with larger unit if needed
	Restriction in line	Check for partially iced coil & check
		temperature split across coil
Compressor runs		Check for oil at silver soldered connections.
	Refrigerant leak	Check for partially iced coil. Check split across
continually & does
not cycle off		coil. Check for low running amperage
	T-stat contacts stuck	Check operation of t-stat. Replace if contacts
		remain closed.
	T-stat incorrectly wired	Refer to appropriate wiring diagram
	Thermistor shorted	Replace thermistor or electronic control board

Problem	Possible Cause	Action
		Disconnect power to unit. Remove cover
	T-stat contacts stuck	of t-stat & check if contacts are stuck. If so,
		replace t-stat
T-stat does not	T-stat set at coldest point	Turn to higher temp. setting to see if unit
		cycles off
turn unit off
	Incorrect wiring	Refer to appropriate wiring diagrams
	Unit undersized for area to be	Refer to industry standard sizing chart
	cooled
	Defective thermistor	Replace thermistor or electronic control board

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