A.Y. McDonald Mfg. Co.
2 HP Grinder Pumps
3210-676 2/21
800.292.2737 | [email protected] | aymcdonald.com
5
Troubleshooting
PROBLEM
CAUSE
CORRECTION
Pump will not run.
1. Poor electrical connection, blown fuse, tripped
breaker or other interruption of power, improper power
supply.
2. Motor or switch inoperative (to isolate cause, go to
manual operation of pump).
2a. Float movement restricted.
2b. Switch will not activate pump or is defective.
3. Insufficient liquid level.
1. Check all electrical connections for security. Have electrician
measure current in motor leads. If current is or-20% of locked
rotor amps, impeller is probably locked. If current is 0, overload may
be tripped. Remove power, allow pump to cool, then re-check current.
2a. Reposition pump or clean basin as required to provide adequate
clearance for float.
2b. Disconnect level control. Set ohmmeter for a low range, such as
100 ohms full scale and connect to level control manually and check
to see that ohmmeter shows zero ohms for closed switch and full
scale for open switch. (Float Switch)
3. Make sure liquid level is at least equal to suggested turn-on point.
4. Re-check all sizing calculations to determine proper pump size.
5. Check discharge line for restrictions, including ice if line passes
through or into cold areas.
6. Remove and examine check valve for proper installation and
freedom of operation.
7. Open valve.
8. Check cutter for freedom of operation, security and condition.
Clean cutter and inlet of any obstruction.
9. Loosen union slightly to allow trapped air to escape. Verify that
turn-off level of switch is set so that the suction is always flooded.
Clean vent hole.
10. Remove & examine for damage. Replace pump stator if required.
11. Repair fixtures as required to eliminate leakage.
12. Check pump temperature limits & fluid temperature.
13. Replace portion of discharge pipe with flexible connector.
14. Turn to automatic position.
15. Check for leaks around basin inlet and outlets.
Pump will not turn off.
2a. Float movement restricted.
2b. Switch will not activate pump or is defective.
4. Excessive inflow or pump not properly sized for
application.
9. Pump may be air locked.
14. H-O-A switch on panel is in “Hand” position.
Pump hums but does not run.
1. Incorrect voltage.
8. Cutter jammed or loose on shaft, worn or damaged,
inlet plugged.
Pump delivers insufficient
capacity.
1. Incorrect voltage.
4. Excessive inflow or pump not properly sized for
application.
5. Discharge restricted.
6. Check valve stuck closed or installed backwards.
7. Shut-off valve closed.
8. Cutter jammed or loose on shaft, worn or damaged,
inlet plugged.
9. Pump may be airlocked.
10. Pump stator damaged / torn.
Pump cycles too frequently or runs
periodically when fixtures are not
in use.
6. Check valve stuck closed or installed backwards.
11. Fixtures are leaking.
15. Ground water is entering basin.
Pump shuts off and turns on
independent of switch, (trips
thermal overload protector).
CAUTION:
Pump may start
unexpectedly. Disconnect power
supply.
1. Incorrect voltage.
4. Excessive inflow or pump not properly sized for
application.
8. Cutter jammed, loose on shaft, worn or damaged,
inlet plugged.
12. Excessive water temperature.
Pump operates noisily or vibrates
excessively.
4. Operating at too high / low of pressure .
5. Discharge restricted.
8. Cutter broken.
13. Piping attachments to building structure too rigid
or too loose.
CAUTION!
Always disconnect the pump from the electrical power source before handling. If the system fails to operate properly, carefully read instructions and
perform maintenance recommendations. If operating problems persist, the following chart may be of assistance in identifying and correcting them:
MATCH “CAUSE” NUMBER WITH CORRELATING “CORRECTION” NUMBER.
NOTE: All 3 Phase Models Check Proper Rotation - Cause Low Performance, Noise, and Vibration
NOTE: Not all problems and corrections will apply to each pump model.
