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HEAT / COOL ROOM AIR CONDITIONERS: TROUBLE SHOOTING TIPS
P
o r
b
e l
m
Unit cools when
heat is called for
P
o r
b
e l
m
Cooling adequate,
but heating
insuffi cient
REFRIGERANT SYSTEM DIAGNOSIS - COOLING CYCLE
LOW SUCTION PRESSURE
Low Load Conditions
Low Air Flow Across
Indoor Coil
Refrigerant System
Restriction
Undercharged
Moisture in System
46
P
o
s
s
b i
e l
Incorrect wiring
Defective solenoid coil
Reversing valve fails to shift
Inoperative system switch
P
o
s
s
b i
e l
Heating capillary tube partially
restricted
Check valve leaking internally
Reversing valve failing to shift
completely; bypassing hot gas
TROUBLESHOOTING CHART — HEATPUMP
HIGH SUCTION PRESSURE
High Load Conditions
High Air Flow Across
Indoor Coil
Reversing Valve not
Fully Seated
Overcharged
Defective Compressor
C
a
u
s
e
Refer to applicable wiring diagram
Check for continuity of coil
Block condenser coil & switch unit to cooling.
Allow pressure to build up in system, then
switch to heating. If valve fails to shift, replace
valve.
Check for continuity of system switch
C
a
u
s
e
Check for partially starved outer coil. Replace
heating capillary tube
Switch unit several times from heating to
cooling. Check temperature rise across
coil. Refer to specifi cation sheet for correct
temperature rise
Deenergize solenoid coil, raise head pressure,
energize solenoid to break loose. If valve fails
to make complete shift, replace valve.
LOW HEAD PRESSURE
Low Load Conditions
Refrigerant System
Restriction
Reversing Valve not
Fully Seated
Undercharged
n i
Defective Compressor
A
t c
o i
n
A
t c
o i
n
HIGH HEAD PRESSURE
High Load Conditions
Low Air Flow Across
Noncondensables (air)
S
s y
e t
m
Outdoor Coil
Overcharged
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Troubleshooting
