IM 1068-2 / Page 23 of 28
Trouble
Cause
Cure
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
under load must be within 10% of voltage given on
data plate.
b. Replace.
c. Tighten.
a. Adjust. Rotate control knob to “Cooler.”
b. Close heat valve.
c. Check as above.
d. Replace.
e. Tighten.
f. Replace.
g. Tighten.
h. Replace.
i. Tighten
j. Replace.
k. *Ship cooling chassis prepaid to nearest McQuay authorized
warranty station.
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.
a. Run separate electric line to equipment. Consult local
power company.
b. Consult local power company.
c. If confirmed, *ship cooling chassis prepaid to nearest McQuay
authorized warranty station.
a. Replace.
b. Replace.
c. Adjust blower motor or blower wheel position.
d. Lubricate motor with SAE #10 oil. (It may be necessary to
remove blower assembly to do this.)
e. Tighten.
a. Adjust blower/fan wheel on shaft or blower motor mounting.
Lubricate with SAE #10 oil (see above).
b. Adjust blower wheel or motor or replace wheel.
a. Eliminate ground.
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.
1) Clean.
2) Remove obstructions.
3) Correct as in #5.
4) Check for correct voltage. Oil blower motor if necessary.
5) Adjust blower position and tighten setscrew.
6) Correct as in #3.
c.
1) Clean.
2) Turn equipment off to let ice melt.
3) Clean or replace.
4) Remove obstructions.
5) Correct as in #1.
6) Check for correct voltage. Oil motor is necessary.
7) Adjust blower wheel position and tighten setscrew.
1. Blowers won't
operate on Cool.
2. Blowers operate on
Cool, but compressor
does not start.
3. Blowers run on Cool
and compressor
starts, but stops after
a short interval.
4. Blowers run on Cool
and compressor
starts and runs, but
compressor
occasionally stops
(on overload device).
5. Compressor starts
and runs on Cool, but
blowers do not run.
6. Compressor starts
and runs on Cool, but
fan motor starts, then
stops.
7. Equipment gives
electrical shock.
8. Insufficient cooling
capacity.
*If equipment is in warranty.
a. No power.
b. Faulty push-button switch.
c. Loose connections at push-button switch.
a. Thermostat set too high.
b. Heat valve is open and heat is on.
c. Low voltage.
d. Faulty push-button switch.
e. Faulty connection at push-button switch.
f. Defective wiring to thermostat.
g. Loose connections at compressor terminals.
h. Wiring to compressor terminals defective.
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).
a. Operation of overload device due to overloaded
compressor motor.
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.
b. High voltage due to fluctuations in local power system;
usually occurs at low load periods of the day.
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.
a. Faulty push-button switch.
b. Open circuited blower motor.
c. Blower rubbing against its housing.
d. Bearings on blower motor seized.
e. Loose connection at push-button switch.
a. Operation of the internally connected overload device due
to a short circuit in blower motor.
b. Windings, rubbing of blower motor or lack of lubrication in
blower motor bearings.
a. Grounded electrical circuit.
a. Equipment standing too long without being run.
b. Insufficient airflow through condenser due to:
1) Dirty condenser.
2) Obstructed louvers on outer cabinet or wall box.
3) Condenser blower/fan not running.
4) Condenser blower/fan not up to speed.
5) Condenser blower/fan slipping on motor shaft.
6) Recirculation of condenser air.
c. Insufficient airflow through evaporator due to:
1) Dirty evaporator.
2) Ice on evaporator coils.
3) Dirty air filter.
4) Obstructed discharge grilles.
5) Evaporator blower motor not running.
6) Evaporator blower motor not up to speed.
7) Evaporator motor slipping on motor shaft.
Troubleshooting Chart
Note: These items should be checked by a qualified service technician only.
Summary of Contents for IM 1068-2
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