Reznor ZQYRA Unit Installation Manual - Manual (Page 67)

Form I-ZQYRA P/N 260414R5, Page 67
DANGER
This unit contains R-410A high pressure refrigerant. Hazards exist that could result in personal
injury or death. Installation, maintenance, and service should only be performed by an HVAC
technician qualified in R-410A refrigerant and using proper tools and equipment. Due to much
higher pressure of R-410A refrigerant, DO NOT USE service equipment or tools designed for R22
refrigerant.
IMPORTANT: Do not release refrigerant to the atmosphere! If required service procedures include the adding
or removing of refrigerant, the service technician must comply with all federal, state and local laws. The proce-
dures discussed in this manual should only be performed by a qualified HVAC technician.
10.3 Troubleshooting
10.3.1 General Troubleshooting
Symptom Possible Cause Corrective Action
"Compressor will
not run or does not
try to start"
Open disconnect switch or circuit breaker. Close switch and / or breaker.
Compressor contactor not closing. Check voltage to contactor coil, transformer, relay, system. Replace parts as
necessary.
Blown fuse or tripped breaker Check for reason and repair. Replace fuse after correcting problem.
Low line voltage. Check line voltage. If more than 10% from compressor marking, correcting
is necessary.
Compressor motor protector open. Motor thermal protector automatically resets. Allow time (2 hrs.) for
compressor to cool down so protector will reset. Restart and check for
reason overheat occurred
Compressor defective. Check motor for open circuit, short circuit, grounded windings or burn
out. Compressor may be seized; check refrigerant. If necessary, replace
compressor.
High or low pressure switch open or defective. If (high pressure), re-set switch. (Switch opens at 600 psi and will not reset
above 420 psi for R-410A.) If HP switch does not reset and everything
else is OK, replace switch. If auto reset (low pressure) does not reset and
everything else is OK, replace switch.
Open room thermostat or control (no cooling
required).
Check room temperature. If temperature is proper, wait for thermostat to
close.
Loose wiring. Check all wire terminals and tighten as necessary.
"Compressor starts
but cuts out on
low pressure. Low
pressure switch
activates at 50 psig
for R-410A."
Low refrigerant charge. Check refrigerant pressures. If refrigerant pressure is low, check for leaks.
Airflow restricted. Check for dirty evaporator coil, dirty filters, dampers closed, iced evaporator
coil, improper belt, check motor amps, check duct design.
Restriction in refrigerant line. Check refrigerant pressure, check and adjust thermal expansion valve. If not
functioning properly, check for pressure drop across the filter drier.
Defective low pressure switch. Replace.
"Compressor
starts but cuts out
on high pressure
switch. High
pressure activates
at 600 psig for
R-410A."
Refrigerant overcharge. Check pressures, charge by subcooling.
In heating mode low air flow over air coil. Change filter or clean air coil.
Air or non-condensables in system. Check high side equalized pressure reading with equivalent outdoor
temperature.
Defective high pressure switch. Replace.
Restriction in discharge or liquid line. Check refrigerant line pressures, check thermal expansion valves.
Reheat valve and bypass valve not opening. Check valves or valve circuit board.
"Compressor cuts
out on thermal
overload."
Low voltage. Check voltage.
Sustained high discharge pressure. Check running amperage and conditions described under ‘Low suction
pressure’ symptoms.
High suction and discharge pressures. Check thermal expansion valve setting; check for air in system.
Defective compressor overload. If compressor is hot, allow compressor to cool for two hours. Recheck for
open circuit.
Improper refrigerant charge. Check subcooling.
Improperly wired. Review wiring schematics.
Loose wiring. Check all connections and wires.
Defective start relay. Replace relay.
Motor windings damaged. Verify amp draw.
"Compressor
hums, but will not
start."
Improperly wired. Review wiring schematics.
Low line voltage. Check voltage.
Loose wiring. Check all connections.
Defective start or run capacitor. Check run capacitor for compressor and fan motor.
Defective relay start. Replace relay.
Motor winding damaged. Verify amp draws.
Internal compressor mechanical damage. Replace.
"Compressor noisy
or vibrating"
Refrigerant overcharge. Check pressures and subcooling.
Liquid floodback. Check thermal expansion valve setting. Check for refrigerant overcharge.
Tubing rattle. Dampen tubing vibration by taping or clamping. Carefully bend tubing away
from contact where possible.
Scroll compressor rotating in reverse (3 phase). Rewire for opposite rotation.
Worn or damaged compressor. Replace the compressor.
Improper mounting on unit base. Check that compressor is properly isolated.
"High suction
pressure"
Excessive load on evaporator coil. Check for high entering wet bulb temperature. Check for excessive air.
Compressor is unloaded. Check head pressure, check thermal expansion valve if not functioning
properly, check pressure drop across filter drier.