Installation Guide

16
TROUBLESHOOTING CHART
WARNING
HIGH VOLTAGE!
D
ISCONNECT ALL POWER BEFORE SERVICING OR INSTALLING THIS UNIT . M ULTIPLE POWER
SOURCES
MAY BE PRESENT . F AILURE TO DO SO MAY CAUSE PROPERTY DAMAGE , PERSONAL
INJURY
OR DEATH .
SYMPTOM
High head - low suction a. Restriction in liquid line or flowrator a. Remove or replace with proper size flowrator.
High head - high or normal suction a. Dirty condenser coi
l
a. Clean coil
b. Overchar
g
ed b. Correct S
y
stem char
g
e
c. Condenser fan not running c. Repair or Replace
a. Incorrect flowrator a. Replace with correct flowrator
b. Defective compressor valves b. Replace compressor
c. Flowrator not seating properly c. Check for debris under flowrator or deformed
flowrator. Remove debris or replace flowrator.
a. Power off or loose electrical
connection
a. Check for unit voltage at contactor in unit
b. Thermostat out of calibration set too b. Reset
c. Defective contactor c. Check for 24 volts at contactor coil replace if
contacts are o
p
en
d. Blown fuses or tripped breaker d. Replace fuse or reset breaker Check wiring -
re
p
lace transformer
e. Transformer defective
f. High or low pressure control open
(
O
p
tional
)
f. Reset high pressure control or check unit charge
High pressure control opens at 610 psig
Low pressure control opens at 22 psig
g. Compressor overload contacts open g. Replace compressor
NOTE: Wait at least 2 hours for overload to
reset
Condenser fan runs,
compressor doesn't
a. Loose connection a. Check for unit voltage at compressor check &
tighten all connections
b. Compressor stuck, grounded or open
windin
g
o
p
en internal overload
b. Wait at least 2 hours for overload to reset
If still o
p
en
,
re
p
lace the com
p
ressor.
c. Low voltage connection c. At compressor terminals, voltage must be within
10 % of nameplate volts when unit is operating
d. Capacitor weak, open, or shorted d. Check capacitor. If defective, replace.
Low suction - cool compressor a. a.
Iced evaporator coil
a. Defective overload protector a. Replace - check for correct voltage
b. Unit cycling on low pressure control b. Check refrigerant charge and / or airflow
c. High pressure switch cuts out c. Check airflow (Indoor & outdoor)
a. a. Increase speed of blower or reduce restriction
replace air filters
a. Excessive load a. Recheck load calculation
b. Defective compressor b. Replace
c. Reversing valve not seating properly. c. Replace
a. Improperly sized unit a. Recalculate load
b. Improper airflow b. Check - should be approximately 400 CFM per ton
c. Incorrect refrigerant charge. c. Charge per procedure attached to unit service
p
anel
d. Incorrect voltage d. At compressor terminals, voltage must be within
10% of nameplate volts when unit is
operating
Evaporator coil freezing or frosting a. Low airflow a. Check - should be approximately 400 CFM per ton,
dirty air filters, all duct outlets open
b. Low refrigerant charge b. Properly charge unit
c. Operating unit in cooling mode below
65°F outdoor temperature
c. Install or check low ambient control, should be
open below 65°F outdoor temperature
Compressor short cycles
Registers sweat Low airflow
High suction pressure
Insufficient cooling
POSSIBLE CAUSE REMEDY
Low head - high suction
Unit will not run
Low indoor airflow Increase speed of blower or reduce restriction -
replace air filters