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noitcA esuaC elbissoP melborP
Unit does not run
Fuse blown or circuit tripped
Replace fuse, reset breaker. If repeats, check
fuse or breaker size. Check for shorts in unit
wiring & components
Power cord not plugged in Plug it in
System switch in “OFF” position Set switch correctly
Inoperative system switch or open
control board
Test for continuity
Loose or disconnected wiring at
switch, control board or other com-
ponents
Check wiring & connections. Reconnect per
wiring diagram
noitcA esuaC elbissoP melborP
Evaporator coil
freezes up
Dirty fi launaM s’renwO ni dednemmocer sa naelC retl
Restricted airfl ow
Check for dirty or obstructed coil. Use
pressure wash or biodegradable cleaning
agent to clean
Inoperative t-stat or thermistors Test for continuity
Short of refrigerant De-ice coil & check for leak
Inoperative fan motor Test fan motor & replace if inoperative
Partially restricted capillary tube
De-ice coil. Check temp. differential (delta T)
across coil. Touch test coil return bends for
same temp. Test for low running current
noitcA esuaC elbissoP melborP
Compressor runs
continually & does
not cycle off
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
Refrigerant leak
Check for oil at silver soldered connections.
Check for partially iced coil. Check split across
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
noitcA esuaC elbissoP melborP
T-stat does not
turn unit off
T-stat contacts stuck
Disconnect power to unit. Remove cover
of t-stat & check if contacts are stuck. If so,
replace t-stat
T-stat set at coldest point
Turn to higher temp. setting to see if unit
cycles off
Incorrect wiring Refer to appropriate wiring diagrams
Unit undersized for area to be
cooled
Refer to industry standard sizing chart
Defective thermistor Replace thermistor or electronic control board
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