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Problem Possible Cause Action
Room temperature
uneven
(Heating cycle)
Heat anticipator (resistor) shorted (on applicable
models)
Disconnect power to unit. Remove resistor from
t-stat bulb block. Plus in unit & allow to operate.
Feel resistor for heat. If not heat, replace resistor
Wide differential - partial loss of t-stat bulb charge Replace t-stat & check
Incorrect wiring
Refer to appropriate wiring diagram. Resistor is
energized during "ON" cycle of compressor or
fan.
Problem Possible Cause Action
Unit will not defrost
Incorrect wiring Refer to appropriate wiring diagram
Defrost control timer motor not advancing
(applicable models)
Check for voltage at "TM" & "TM1" on timer. If no
voltage, replace control
Defrost control out of calibration (applicable
models)
If outside coil temperature is 25F or below, &
preselected time limit has elapsed, replace
defrost control
Defrost control contacts stuck
If contacts remain closed between terminals "2"
& "3" of the defrost control after preselected time
interval has passed, replace control
Defrost control bulb removed from or not making
good coil contact
Reinstall & be assured that good bulb to coil
contact is made
Problem Possible Cause Action
Does not heat
adequately
Exhaust or fresh air door open
Check if operating properly. Instruct customer on
proper use of control
Dirty fi lter Clean as recommended in Owner's Manual
Unit undersized
Check heat rise across coil. If unit operates
effi ciently, check if insulation can be added
to attic or walls. If insulation is adequate,
recommend additional unit or larger one
Outdoor t-stat open (applicable models)
T-stat should close at 38°F. Check continuity of
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
HEAT / COOL ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS