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TROUBLESHOOTING
CHART
WARNING
HIGH VOLTAGE!
_
I_
DISCONNECT ALL POWERBEFORESERVICING OR INSTALLING THIS UNIT, MULTIPLEPOWERSOURCESMAY BE PRESENT,
FAILURE TO DO SO MAY CAUSEPROPERTY DAMAGE,PERSONALINJURYOR DEATH,
SYMPTOM
POSSIBLE CAUSE
REMEDY
High head - low suction
a. Restriction in liquid line or flowrator
a. Remove or replace with proper size flowrafor.
High head - high or normal suction
a. Dirtycondenser coil
a. Clean coil
b. Overcharged
b. Correct System charge
c. Condenser fan notrunning
c. Repair or Replace
Low head - high suction
a. Incorrect fiowrator
a. Replace with correct fiowrator
b. Defective compressor valves
b. Replace compressor
c. Flowrator not seating properly
c. Check for debris under fiowrator ordeformed
flowrator. Remove debris or replace flowrator.
Unit will not run
Power off or loose electrical connection
Check for unit voltage at contactor in unit
Condenser tan runs,
compressordoesn't
a.
b.
C.
Thermostat out of calibration set too high
Defective contactor
d. Blown fuses or tripped breaker
e. Transformer defective
f. High or low pressure control open
(Optional)
Compressor ovedoad contacts open
Loose connection
g.
a.
b.
C.
d.
a.
a.
b.
a.
a.
b.
C.
a.
b.
C.
d.
Compressor stuck, grounded or open
windingopen internal overload
Low voltage connection
Capacitor weak, open, or shorted
Low suction- cool compressor
Low indoor airflow
Iced evaporator coil
Compressor short cycles
Defective overload protector
Unit cyclingon low pressure control
Registers sweat
Low airflow
High suctionpressure
Insufficientcooling
Excessive load
Defective compressor
Reversing valve not seating properly.
Improperlysized unit
Improper airflow
Evaporator coilfreezing or frosting
Incorrectrefrigerant charge.
a.
b.
C.
Incorrectvoltage
Low airflow
Low refrigerant charge
Operating unit in cooling mode below
65°F outdoortemperature
a.
b.
C.
d.
Reset
Check for 24 volts at centactor ceil replace if
contacts are open
Replace fuse or reset breaker Check wiring -
replace transformer
f. Reset high pressure control or check unit charge
High pressure control opens at 425 psig
Low pressure control opens at 25 psig
g. Rep]ace compressor
NOTE: Wait at least 2 hoursfor overload to reset
a. Check for unitvoltage at compressor check &
tighten all connections
b. Wait at ]east 2 hoursfor ovedoad to reset If still
open, replace the compressor.
c. At compressor terminals, voltage must be within
10 % of nameplate volts when unit is operating
d. Check capacitor. If defective, replace.
a. Increase speed of blower or reduce restriction-
replace air filters
a. Replace - check for correct voltage
b. Check refrigerantcharge and / or airflow
a. Increase speed of blower or reduce restriction
replace air filters
a. Recheck load calculation
b. Replace
c. Replace
a. Recalculate load
b. Check - shouldbe approximately400 DFM per
ton
c. Charge per procedure attached to unit service
panel
d. At compressor terminals, voltage must be within
10% of nameplate volts when unit is operating
a. Check - shouldbe approximately400 CFM per
ton, dirty air filters, all duct outlets open
b. Properly charge unit
c. Install or check low ambient control, shouldbe
open below 65°F outdoortemperature
13
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