Introduction
There is not a single listing of motor troubleshooting procedures to be followed in a given order. The procedures will differ depending on the situation.
As with anything dealing with electricity, personal safety is of prime concern. Before you even touch the motor, MAKE SURE THE POWER IS OFF. Always turn the power off at the electric service fuse or breaker box. To prevent electrical shock, use a meter to check for electrical shorts and be sure the motor is securely grounded and bonded in conformity with local codes. Do not work on electrical devices if water or moist conditions are present and cannot be avoided.
Motor Fails to Start (Makes No Sound)
- Check the obvious first. Are the power switch and timer on?
- Check for blown fuse or circuit breaker. If fuses are used, be sure fuses are the proper size or type.
- WITH THE POWER OFF, check all connections on the terminal board. Verify they are correct by consulting the wiring diagram on the motor. Make sure all connections are tight, including the ground wire.
- Check the voltage at the terminal board after first turning the power back on. Be sure to TURN THE POWER BACK OFF after completing this step. Note: Voltage at motor terminals should be + or - 10% of the voltage on the nameplate. If the voltage is high, contact the local Power Company. If the voltage is low, check the wire size of the power line from the electric box to the motor.
Motor Starts But Shuts Down (Thermal Overload Protection)
- Check the voltage at motor terminal. If it is too high, call the local Power Company.
- Check amperage. If high, find out if the pump impeller was recently replaced (it could be sized incorrectly). Remember, motor horsepower times the service factor = total horsepower. Total horsepower must be equal to or greater than the impeller rating. Check for overloads.
Noisy Motor
- Check motor coupling, brackets, and other attached parts. Tighten loose nuts, bolts, or set screws.
- Turn shaft. If it is rough or tight, check bearings.
- Look for loose or binding parts inside the motor or the pump.
- Pump cavitation.
Overheating (Smoking or Cycling)
- Check the motor's ventilation by looking for clogged air vents or openings. Clean away all dirt and leaves or other debris from around the motor.
- Check internal cooling fan. Is it intact and operating properly?
Troubleshooting Additional Checks
Low or High Voltage
Compare connections to wiring diagram. Make sure motor is connected correctly for applied voltage. Voltage should be + or - 10% of nameplated voltage. If higher than +10%, call the local power company. If lower than -10%, check wire size from the service fuse box or circuit breaker. If voltage is low from the service, use a motor one increment higher in horsepower or an E-plus or Conservationist high efficiency motor of the same horsepower and service factor.
TIP: Electric demand on the power company varies. If the motor is nuisance tripping because of low voltage, it may only trip during the part of the day when electrical usage is the highest. Do your voltage checks at that time of day.
High Ambient Temperatures
Pool motors are usually designed to operate in 50 degree C ambients (122 degrees Fahrenheit). Artificially high ambients can occur if a motor operates in a confined space and recirculates the same air or circulates air from another motor next to it.
Check Amp Draw
If the amps are higher than nameplate amps but the voltage is acceptable, WITH THE POWER OFF, inspect the motor and the pump for mechanical obstructions that could cause an overload.
Motor Windings and Capacitors
Look at motor windings and capacitors for damage or signs of shorting. Check for continuity.
Application Overload
In cases of flooded suction or positive pressure on the inlet side of the pump, flow may be increased, overloading the pump.
Misapplication
Make sure the motor is not undersized. Remember that total horsepower is horsepower times service factor. The total horsepower must be equal to or greater than the pump/impeller rating.
Start Switch and Governor
Check the motor start switch and governor (if applicable) to make sure it is adjusted properly and is operational.
Test Equipment
Conventional Multimeter or Ohmmeter
An ohmmeter can be used to measure the resistance of the various motor windings as well as to test the insulation. The ohmmeter will have numerous ranges from R x 1 (where the meter reads directly in ohms) to R x 100K (where the actual meter reading must be multiplied by 100,000 for the actual ohm value).
Before Using an Ohmmeter
- Make sure the power is off.
- Read the instruction manual for the meter.
- All troubleshooting checks specify the ohmmeter range to be used. If your meter does not have the exact range, use the next higher range.
[Illustration of an analog ohmmeter with its red and black probes.]
Digital Ohmmeter/Multimeter
Direct reading digital ohmmeters are readily available in the field.
To Use This Type
- Make sure the power is off.
- Read instruction manual for the meter.
- You do not have to set the ohmmeter to a particular scale as the meter displays the ohm value up to maximum capability of the meter.
- Install probes and take resistance readings in the normal manner.
[Illustration of a digital multimeter.]
Ammeter and Voltmeter
Voltmeter Readings
Install leads in bottom of ammeter. Select the desired voltage scale. Take readings by touching one probe to each of the lead line terminals.
Ammeter Readings
- Arrange leads so the jaws of the ammeter will encircle one lead.
- Set meter on maximum amp scale and encircle jaws around one lead and take reading. It may be necessary to reset to a lower scale.
[Illustration of an analog clamp meter (ammeter) and a voltmeter setup with probes.]
Electrical Checks
Voltage Check
- Make sure power is off.
- Determine motor voltage and set meter.
- Reconnect power.
- Start the motor.
Caution: All wires are live (hot) so use extensive care.
Touch one probe to L1 and the other to L2. Voltage reading to be within 10% of nameplate voltage (e.g., between 207 and 253 volts for a motor nameplated 230 volts).
If no voltage is recorded, check fuses, circuit breakers, timers, wiring, etc., for open connections or broken wires.
If voltage is outside the acceptable limits, check for adequate wire size. Look for loose terminals and connections or pitted contacts. Check pump disconnect switch.
Check voltage at service entrance. If not within plus or minus 10%, contact power company.
[Close-up views of motor electrical connections with test probes attached to terminals L1 and L2.]
Amperage Check
- Make sure power is off.
- Set ammeter scale based on Max. Load amps.
- Position one line lead (L1 or L2) so that the jaws of the ammeter can encircle one power lead. (It will usually be necessary to install a test loop to have room for the meter jaws.)
- Make sure switch and governor are free of obstructions (if applicable).
- Reconnect power.
- Start the motor.
Caution: All wires are live (hot) so use extensive care.
Take a reading. The value should not exceed maximum load amps (service factor amps) on the motor nameplate.
Excessive amps means an overloaded condition or incorrect voltage applied. The problem could also be a short in the motor.
[A clamp meter positioned around a power lead (L1 or L2) for amperage measurement.]
Component Checks
Ground Check
- Turn the power off.
- Set ohmmeter to R x 1K.
- Attach one probe to the ground screw on the end frame and touch the other probe to all terminals on the terminal board, switch, capacitor, and protector. A reading of less than 10K could indicate a ground. New motors typically read over one megohm. Old motors with dust, dirt, and moisture could show resistance to ground below 10K and still run satisfactorily. A cleaning may be in order. Readings may vary from day to day depending on humidity levels. Approximately 25K at 115 volts will trip the ground fault device. Keep in mind the ground fault device is seeing the total leakage of all loads on the circuit. GFI's normally trip on readings from 4 to 6 milliamps.
- If grounded, check all external leads for cuts, breaks, frayed wires, etc. Replace damaged leads and recheck for grounds and proper lead routings. Make sure replaced leads are not pinched between canopy or cover and end frame. If ground is in the stator, the motor must be replaced.
[Close-up views of motor components, including the terminal board, capacitor, and switch, with test probes connected for checks.]
Start Switch Check (if applicable)
Visual Checks
- Make sure power is off.
- Remove Canopy.
Discharge capacitor by touching the two terminals simultaneously with the blade of an insulated handle screwdriver.
Make sure there are no obstructions preventing the proper operation of the rotating governor. Check wiring and make sure none of the leads are in the area of the governor where they can be cut or interfere with the governor. Check governor for proper operation and make sure flipper moves freely.
Check switch contacts for severely burned or pitted contacts, sticking, etc. Some blackening or pitting is normal after the motor has been used. Replace switch if there is any doubt. DO NOT try to repair the switch by bending the contact blades.
The switch contacts in motors are plated and should never be sanded, which would remove the plating and cause early failure. They may be cleaned by wiping the contacts with a piece of cardboard or paper bag.
- Attach one lead to each terminal of the switch. Ohmmeter reading should be 0. With one lead on each terminal, flip governor weight to the run position. Reading should be infinity.
Reconnect power.
Start the motor. Visually check the action of the switch and governor. Switch contacts must be closed when the motor is at rest and should open when the motor reaches about 2/3 of full load speed.
TIP: Replace the capacitor and switch at the same time. A defective switch usually stresses the start capacitor.
Winding Continuity
For typical two-compartment, single-phase, dual-voltage motor, capacitor start, single speed, connected for 230 volts: Set meter to R x 1.
(For single voltage motors, check between L1 and L2.)
[Diagrams illustrating probe placement on motor terminals (L2, A, Yellow, Red) and a detailed wiring schematic showing internal motor connections.]
Protector (Thermal Overload) Check
- Set ohmmeter to R x 1.
- Resistance between terminals:
- 1 & 2 should be approximately 0 (Disc.).
- 2 & 3 should be approximately 0 (Heater).
- Replace if either value exceeds 1 ohm.
TIP: Motor cycling on overload indicates some other problem not just a defective overload.
[Photograph of a thermal overload protector with numbered terminals (1, 2, 3).]
Capacitor Check (Start or Run)
- Set ohmmeter at Rx 1K.
- Slip a heavy piece of paper between points on the switch.
- Discharge capacitor by touching the two terminals simultaneously with the blade of an insulated handle screwdriver.
- Attach one probe to each terminal. Ohmmeter needle should move rapidly to right then slowly drift to the left (low ohm reading to high ohm reading).
- If a digital meter is used, readings should start low and rapidly increase to maximum value.
- Replace capacitor if bad.
TIP: The replacement capacitor must be the same MFD as the original. However, if the same voltage rating is not available, it is acceptable to use the next higher voltage. Example: if a 370-volt unit is not available, use the next rating, 440-volt.
[Photograph of a cylindrical motor capacitor with terminals.]
