Troubleshooting Chart
Symptom
Compressor will not run
Motor hums but cannot
run or runs slowly
Fuses blow/circuit
breaker trips repeatedly
Thermal overload
protector cuts out
repeatedly
Air receiver pressure
drops when compressor
shuts off
Excessive moisture in
discharge air
Compressor runs
continuously
Compressor vibrates
Air output lower than
normal
Possible Cause(s)
1. Loss of power or overheating
2. No electrical power
3. Blown fuse
4. Breaker open
5. Thermal overload open
6. Pressure switch bad
1. Low voltage
2. Wrong gauge wire or length of
extension cord
3. Shorted or open motor winding
4. Defective check valve or unloader
1. Incorrect size fuse, circuit overloaded
2. Wrong gauge wire or length of
extension cord
3. Defective check valve or under loader
1. Low voltage
2. Clogged air filter
3. Lack of proper ventilation/room
temperature too high
4. Wrong gauge wire or length of
extension cord
1. Loose connections (fittings, tubing,
etc.)
2. Loose drain lock
3. Check valve leaking
1. Excessive water in air receiver
2. High humidity
1. Defective pressure switch
2. Excessive air usage
3. Check valve leaking
Loose mounting bolts
1. Broken inlet valves
2. Intake filter dirty
3. Connections leaking
Corrective Action
1. Check for proper use of extension cord (see
EXTENSION CORDS, page 3)
2. Plugged in? Check fuse/breaker or motor overload
3. Replace blown fuse
4. Reset, determining why problem happened
5. Motor will restart when cool; turn off compressor and
wait 20 minutes.
6. Replace
1. Check with voltmeter
2. Check gauge chart, under Operation for proper
gauge wire and cord length
3. Replace motor
4. Replace or repair
1. Check for proper fuse, use time-delay fuse.
Disconnect other electrical appliances from circuit or
operate compressor on its own branch circuit
2. Check gauge chart, under Operation
3. Replace or repair
1. Check with voltmeter
2. Clean filter (see Maintenance section)
3. Move compressor to well ventilated area
4. Check gauge chart, under Operation
1. Check all connections with soap and water solution
and tighten
2. Tighten
3. Disassemble check valve assembly, clean or replace
1. Drain receiver
2. Move to area of less humidity; use air line filter
1. Replace switch
2. Decrease air usage; compressor not large enough for
a requirement
3. Disassemble check valve assembly, clean or replace
Tighten
1. Have authorized service representative repair unit
2. Clean or replace intake filter
3. Tighten connections
7
HM7500
Do not disassemble check valve
with air in tank; bleed tank
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