19
Air-Cooled Condensing Units
Quarterly
1) Visually inspect unit
• Look for signs of oil stains on interconnection piping and condenser
coil. Pay close attention to areas around solder joints, building
penetrations and pipe clamps. Check any suspect areas with an
electronic leak detector. Repair any leaks found and add refrigerant as
needed.
• Check condition of moisture indicator/sightglass in the sight glass if
so equipped. Replace liquid line drier if there is indication of slight
presence of moisture. Replace refrigerant, oil and drier if moisture
concentration is indicated to be high.
Unit Coolers
At every six month interval, or sooner if local conditions cause clogging
or fouling of air passages through the finned surface, the following items
should be checked.
1) Visually inspect unit
• Look for signs of corrosion on fins, cabinet, copper tubing and
solder joints.
• Look for excessive or unusual vibration for fan blades or sheet metal
panels when in operation. Identify fan cell(s) causing vibration and
check motor and blade carefully.
• Look for oil stains on headers, return bends, and coil fins. Check any
suspect areas with an electronic leak detector.
• Check drain pan to insure that drain is clear of debris,
obstructions or ice buildup and is free draining.
2) Clean evaporator coil and blades
• Periodic cleaning can be accomplished by using a brush, pressurized
water or a commercially available evaporator coil cleaner or mild
detergent. Never use an acid based cleaner. Follow label directions for
appropriate use. Be sure the product you use is approved for use in
your particular application.
• Flush and rinse coil until no residue remains.
• Pay close attention to drain pan, drain line and trap.
3) Check the operation of all fans and ensure airflow is
unobstructed
• Check that each fan rotates freely and quietly. Replace any fan motor
that does not rotate smoothly or makes an unusual noise.
• Check all fan set screws and tighten if needed.
• Check all fan blades for signs of stress or wear.
Replace any blades that are worn, cracked or bent.
• Verify that all fan motors are securely fastened to the motor rail.
• Lubricate motors if applicable.
4) Inspect electrical wiring and components
• Visually inspect all wiring for wear, kinks, bare areas and discoloration.
Replace any wiring found to be damaged.
• Verify that all electrical and ground connections are secure, tighten
if necessary.
• Check operation/calibration of all fan cycle and defrost controls
when used.
• Look for abnormal accumulation of ice patterns and adjust defrost
cycles accordingly
• Compare actual defrost heater amp draw against unit data plate.
• Visually inspect heaters to ensure even surface contact with the coil. If
heaters have crept, decrease defrost termination temperature and be
sure you have even coil frost patterns. Re-align heaters as needed.
• Check drain line heat tape for proper operation (supplied and installed
by others).
5) Refrigeration Cycle
• Check unit cooler superheat and compare reading for your specific
application
• Visually inspect coil for even distribution
• Check moisture indicator/sightglass for flash gas. If found check
entire system for refrigerant leaks and add refrigerant as needed after
repairing any leaks.
• Check compressor sightglass (if equipped) for proper oil level.
• Check condition of condenser. Look for accumulation of dirt and debris
(clean as required).
• Check for unusual noise or vibration. Take corrective action as required.
• Inspect wiring for signs of wear or discoloration and repair if needed.
• Check and tighten all flare connections.
Semi-Annually
2) Repeat all quarterly inspection items.
3) Clean condenser coil and blades
• Periodic cleaning can be accomplished by using a brush, pressurized
water and a commercially available foam coil cleaner. If foam cleaner is
used, it should not be an acid based cleaner. Follow label directions for
appropriate use.
• Rinse until no residue remains.
4) Check operation of condenser fans
• Check that each fan rotates freely and quietly. Replace any fan motor
that does not rotate smoothly or makes excessive noise.
• Check all fan blade set screws and tighten as required.
• Check all fan blades for signs of cracks, wear or stress. Pay close
attention to the hub and spider. Replace blades as required.
• Verify that all motors are mounted securely.
• Lubricate motors if applicable. Do not lubricate permanently sealed,
ball bearing motors.
5) Inspect electrical wiring and components
• Verify that all electrical and ground connections are secure, tighten as
required.
• Check condition of compressor and heater contactors. Look for
discoloration and pitting. Replace as required.
• Check operation and calibration of all timers, relays pressure controls
and safety controls.
• Clean electrical cabinet. Look for signs of moisture, dirt, debris, insects
and wildlife. Take corrective action as required.
• Verify operation of crankcase heater by measuring amp draw.
6) Check refrigeration cycle
• Check suction, discharge and net oil pressure readings. If abnormal take
appropriate action.
• Check operation of demand cooling, liquid injection or unloaders if so
equipped.
• Check pressure drop across all filters and driers. Replace as required.
• Verify that superheat at the compressor conforms to specification. (30°F
to 45°F)
• Check pressure and safety control settings and verify proper operation.
Annually
7) In addition to quarterly and semiannual maintenance checks, submit an
oil sample for analysis
• Look for high concentrations of acid or moisture. Change oil and driers
until test results read normal.
• Investigate source of high metal concentrations, which normally
are due to abnormal bearing wear. Look for liquid refrigerant in the
crankcase, low oil pressure or low superheat as a possible source.
8) Inspect suction accumulator (if equipped)
• If the accumulator is insulated remove insulation and inspect for leaks
and corrosion.
• Pay close attention to all copper to steel brazed connections
• Wire brush all corroded areas and peeling paint.
• Apply an anticorrosion primer and paint as required. Re-insulate if
applicable.
Preventive Maintenance