McQuay air conditioner troubleshooting

You can fix minor problems in the operation of the air conditioner on your own, in case you have an understanding of how the device operates and if you use air conditioner manual and simple tools. In case of serious malfunction of the device, you should contact a specialist.

McQuay MCK020A air conditioner troubleshooting

FaultCause
1. Compressor does not work 3 minutes after starting.• Protection against frequent starting. Wait for 3 to 4 minutes.
2. The unit does not work.• Power failure or need to replace the fuse.
• The power plug is disconnected.
• It is possible that your delay timer has been set incorrectly.
• If the fault persist after the verifications, contact your installer.
3. The air flow is too low.• The air filter is dirty.
• The door and windows are opened.
• The suction and discharge are clogged.
4. The remote control light is dim.• Battery flat.
• Batteries are incorrectly inserted or misplaced.
5. Air discharge has bad front.• Odors may be caused by cigarette, smoke particles, perfume etc..which adhere to the coil.
6. Condensation on the front panel.• This is due to air humidity after a long time operation.
• The set temperature is too low, increase the temperature and change it to high fan.
7. Hissing sound during operation.• Refrigerant flow into evaporator oil.

McQuay PTAC air conditioner troubleshooting

TROUBLECAUSECURE
1. Blowers won’t operate on COOL.a. No power.a. Check supply line fuses, circuit breakers, and be sure the power is on. Blown fuses would indicate circuit overloading, a short circuit, or a grounded condition in the circuit. Voltage supply to the equipment should be checked. Voltage must be within 10% of voltage given on data plate.
b. Faulty pushbutton switch.b. Replace.
c. Loose connections at pushbutton switch.c. Tighten.
2. Blowers operate on COOL but compressor doesn’t start.a. Thermostat set too high.a. Adjust. Rotate control knob to “Cooler.”
b. Heat valve is open and heat is on.b. Close heat valve.
c. Low voltage.c. Check as above.
d. Fault pushbutton switch.d. Replace.
e. Faulty connection at pushbutton switch.e. Tighten.
f. Defective wiring to thermostat.f. Replace.
g. Loose connections at compressor terminals.g. Tighten.
h. Wiring to compressor terminals defective.h. Replace.
I. Loose connections in compressor overload device, j. Starting capacitor malfunctions (open circuited, short circuited or loss of capacity, k. Defective compressor motor (short circuited, open circuited, grounded).i. Tighten, j. Replace.
k. 'Replace cooling chassis prepaid to nearest McQuay authorized warranty station.
3. Blowers run on COOL and compressor starts but stops after a short interval.a. Operation of overload device due to overloading compressor motor.a. Check voltage supply. Clean condenser inside and out. Check at outside face of condenser for recirculation of condenser air. Put air “splitters” in, if missing. Check to make sure condenser blower/fan is operating properly. Check compressor for short circuit. If defective, ‘ship cooling chassis to nearest McQuay authorized warranty station.
4. Blowers run on COOL and compressor starts and runs, but compres- sor occasionally stops (on overload device).a. Low voltage due to overloaded circuits within building or throughout the local power system. Due to varying power demands, this condition might exist only at certain times during the day or on very hot days.a. Run separate electric line to equipment. Consult local power company.
b. High voltage due to fluctuations in local power system; usually occurs at low load periods of the day.b. Consult local power company.
c. Partial short circuit in compressor motor. Under normal loading a compressor with a partial short circuit might appear to be operating all right; increased condensing air temperature might then cause a short.c. If confirmed, ship cooling chassis prepaid to nearest McQuay authorized warranty station.
5. Compressor starts and runs on COOL but blowers do not run.a. Faulty pushbutton switch.a. Replace.
b. Open circuited blower motor.b. Replace.
c. Blower rubbing against its housing.c. Adjust blower motor or blower wheel position.
d. Bearings on blower motor seized.d. Lubricate motor with SAE No. 10 oil. (It may be necessary to remove blower assembly to do this.)
e. Loose connection at pushbutton switch.e. Tighten.
6. Compressor starts and runs on COOL but blowers do not run.a. Operation of the internally connected overload device due to a short circuit in blower motor.a. Adjust blower/fan wheel on shaft or blower motor mounting. Lubricate with SAE No. 10 oil (see above).
b. Windings, rubbing of blower wheel or lack of lubrication in blower motor bearings.b. Adjust blower wheel or motor or replace wheel.
7. Equipment gives electrical shock.a. Grounded electrical circuit.a. Eliminate ground.
8. Insufficient cooling capacity.a. Equipment standing too long without being run.a. If the air conditioner is allowed to stand for an extended length of time without being run on COOL, it is possible for all the refrigerant to become absorbed in the oil inside the compressor and refrigeration circuit. If this should happen, there will be no cooling until the necessary working pressures have been established. This will take about 5 minutes of continuous running.
b. Insufficient airflow through condenser due to:b.
1) Dirty condenser.1) Clean.
2) Obstructed louvers on outer cabinet or wall box.2) Remove obstructions.
3) Condenser blower/fan not running.3) Check same as in the case of malfunctioning conditioner air blower.
4) Condenser blower/fan not up to speed.4) Check for correct voltage. Oil blower motor if necessary.
5) Condenser blower/fan slipping on motor shaft.5) Adjust blower position and tighten setscrew.
6) Recirculation of condenser air.6) Correct as in No. 3 above.
c. Insufficient airflow through evaporator due to:c.
1) Dirty evaporator.1) Clean.
2) Ice on evaporator coils.2) Turn equipment off to let ice melt.
3) Dirty air filter.3) Clean or replace.
4) Obstructed discharge grilles.4) Remove obstructions. In case of top discharge equipment, make sure books, magazines, etc., are kept off the equipment.
5) Evaporator blower motor not running.5) Check as in No. 1.
6) Evaporator blower motor not up to speed.6) Check for correct voltage. Oil motor if necessary.
7) Evaporator blower slipping on motor shaft.7) Adjust motor wheel position and tighten setscrew.
d. Heat load in room exceeds capacity of equipment.d. Recalculate heat load.
e. Windows and doors in room are open.e. Close therm.
9. Too much cooling.a. Thermostat set too low.a. Adjust.
b. Defective thermostat.b. Replace.
10. “Sweating”a. Condensate drain from evaporator to condenser plugged.a. See No. 1.
b. Insulating seals on equipment damaged.b. Open heat valve or turn on heating system.
c. Evaporator blower motor not up to speed.c. Check for correct voltage. Oil motor if necessary.
d. Evaporator blower incorrectly positioned.d. Adjust.
11. Blowers won’t operate on HEAT.a. No power.a. See No. 1.
b. Heat is off (equipment with heat fan lockout).b. Open heat valve or turn on heating system.
c. Faulty pushbutton switch.c. Replace.
d. Loose connections at pushbutton switch.d. Tighten.
e. Thermostat set too low.e. Adjust. Rotate control knob to “Warmer.”
12. "Equipment is noisy.a. Blower rubbing against enclosure.a. Adjust fan position on motor shaft or reposition fan motor bracket assembly.
b. Blower motor bearings are dry.b. Lubricate with SAE No. 10 or replace motor.
c. Loose blower hold-down nuts on motor-bracket assembly.c. Align blower assembly and tighten nuts.
d. Refrigerant absorbed in compressor oil after extended shutdown.d. Noise will disappear after equipment runs awhile.
e. Equipment improperly installed.e. Make necessary adjustments to components.
f. Damper solenoid hums.f. Check for proper adjustment. Apply silicone oil or grease to gap between solenoid and armature.
g. Loose terminal box cover on side of compressor.g. Tighten.
h. Loose electrical components.h. Fasten securely.
i. Copper tubing vibrating, j. Harmonics.i. Adjust by bending or applying tape.
k. Loose sheet metal parts.j. Occasionally equipment will have noisy operation for no ap- parent reason. Inspection has revealed no loose components that might be the source of the noise. Due to the action of the compressor, it is possible to have internal noise develop if the refrigerant tubing has become bent even slightly. To distin- guish this condition from the simple rattle producing vibration caused by loose screws, nuts and other components, grasp the refrigerant tubing at various points throughout the system until a point is found where the noise is eliminated or reduced. Bend the copper tubing very gently until the noise disappears.
k. Tighten.
13. Insufficient or no heat.a. No steam or hot water being applied.a. Contact building management.
b. No power.b. Check power supply line fuses, circuit breakers. Blown fuses would indicate circuit overloading, a short circuit, ora grounded condition in the circuit.
c. Faulty pushbutton switch.c. Replace.
d. Loose connection at pushbutton switch.d. Replace wire or tighten.
e. Thermostat set too high.e. Adjust rotate knob to “Warm."
f. Thermostat faulty.f. Replace.
g. No power output on transformer secondary.g. Replace.
h. Inoperative valve.h.
1) Steam valve N/C.1) Temporary lock valve open; replace.
2) Hot water valve N/O.2) Replace.

McQuay MCM020D Air Conditioner Troubleshooting

FAULTCAUSE
1. Fan does not work 3 minutes after starting• Protection against the frequent starting. Wait 3 or 4 minutes.
2. The air conditioning unit does not work• Power failure or you must be replaced the fuse.
• The power plug is disconnected.
• Possibility of making a programming error in the controller.
• If the fault persists after these verifications, contact your installer.
3. The air conditioning unit does not blow sufficiently• The air filter is dirty.
• The doors or windows are open.
• The air entrance and exit are clogged.
• The regulate temperature is not high enough.
4. The remote control lignt is deficient• The batteries are discharge.
• The batteries are not correctly inserted.
• The assembly is not good.
5. Air discharge flow has a bad odor• This odor can be caused by cigarette smoke particles, perfume, sweat, which sticks to the coil.
• Check if there is any moisture on the walls, garment, other.
• Check the drain pan.
6. Condensation on the air grille of indoor unit• This is due to air humidity after a long time of operation.
• The unit has a lower temperature point, increase the point and operate at high speed.
7. The water flow of air conditioning unit• Check the condensate evacuation.
8. The air conditioning unit is noisy• “Air flow noise”: refrigerant fluid admission in evaporator.

McQuay MWM Air Conditioner Troubleshooting

Problem SymptomCheck ItemSuggested Action
The unit does not workCheck the power supplyCheck to make sure that the rated voltage is supplied.
Check the fuseCheck and replace the fuse.
Check the remote controller timer settingMake sure the delay timer is set correctly.
Fan does not workCheck the power supplyCheck to make sure that the rated voltage is supplied.
Check the fan motor capacitorCheck and replace the capacitor.
Check the fan motorCheck and replace the fan motor.
Check the switchCheck and change the switch.
Fan work, but compressor does not workCheck if the thermostat setting too highReset thermostat.
Check the compressor capacitorCheck and replace the capacitor.
Check the compressorCheck and replace the compressor.
Check the compressor contactorCheck and replace the contactor.
Air conditioner work but cooling not satisfactoryCheck if the thermostat setting too highReset thermostat.
Check if the condenser coil dirtyClean the condenser coil.
Check the condenser installation conditionMake sure the condenser is installed According to factory's recommendation.
Diagnosis by service port pressure and operating CurrentCheck for insufficient refrigerant.
The air flow is too lowCheck the air filterCheck and make sure the air filter is clean.
Check the fan / blower conditionCheck and make sure that the fan / blower are in good condition.
The remote controller light is dimCheck the batteryCheck and replace the battery.
Make sure the batteries are correctly inserted.