F.A.Q.'s Section

We've put together a list of most common air compressor questions and problems and their answers or possible solutions to help you quickly trouble shoot your air compressor. If you have any specific questions not answered here, please call or email us - go to Contact Us section - and we will be glad to help.


Click on the question or problem below to link to the answer or possible solution:


    What is CFM?
  1. CFM (cubic feet per minute) refers to the volume of air produced by the compressor at a given pressure or PSI (pounds per square inch)
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    What size tank do I need?
  1. The size of the compressor tank, usually measured in gallons, should be determined by the overall type of usage. If the usage is short quick concentrated spurts, such as a nailer then a small tank can be used. If the unit is to sustain long periods of usage, such as a board sander or impact wrench, a larger tank will be necessary.
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    What voltage do I run on?
  1. Most direct-drive electric compressors run on a standard 110 volt circuit. For jobs that require more air, usually a 220 volt will be your only choice. When using a stationary compressor, you will need to know what power supply you have (208V, 230V, or 460V) and if it is single or three phase power. The majority of the time units with motors of 5HP or more require a magnetic starter which is hard wired into the power supply. This is used to protect the motor from overloading.
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    Do I need Single-Stage or Two Stage pump?
  1. Single stage air compressors work by drawing air in and compressing the air to its final stage in a single piston stroke. Pressures up to 150 PSI.
  2. Two stage compressors work in a similar manner with the difference being that they compress the air in 2 steps. After the air is compressed in the first step, it is then compressed again. Pressures up to 200 PSI. If you require constant pressure of 100 PSI, get a 2 stage.
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    Why do I get water in my lines?
  1. When air is compressed it gets hot. And when the air cools moisture condenses out of it. To prevent air in the lines drain the air tank frequently. You could consider adding an automatic drain to eliminate having to do this manually. Also adding a water trap to your lines can help. In some commercial situations an air dryer can be installed.
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    How do I prevent oil in the airlines?
  1. A Coalescing filter will take out most of the oil, but if you are getting a lot of oil in your lines, then the piston rings should be replaced.
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    Why is my compressor running hot?
  1. Elevated temperature may be caused by restricted air flow, the temperature of the room, or the incorrect oil level.
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    Motor will not run
  1. Improper line voltage - check line voltage, change lines as required.
  2. Poor contact on motor terminals or starter connections - ensure good contact on motor terminals and starter connections.
  3. Improper starter heaters - install proper starter heaters.
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    Oil in discharge gas
  1. Clogged or dirty inlet and/or discharge filter - replace filter element.
  2. Oil viscosity too low - Drain existing lubricant from frame. Refill with proper lubricant.
  3. Oil level too high - Drain lubricant from frame to proper level.
  4. Detergent type lubricant being used - Drain existing lubricant from frame. Refill with specified lubricant.
  5. Piston rings damaged or worn (broken, rough, scratched, excessive end gap or side {clearance) - Replace piston rings.
  6. Piston rings not seated, stuck in grooves, or end gaps not staggered. - Clean and adjust piston rings. Replace as required.
  7. Cylinder scratched, worn or scored. - Replace or repair as required.
  8. Piston scratched, worn or scored. - Repair or replace as required.
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    Knocks or rattles
  1. Loose belt wheel or motor pulley. Excessive end play in motor shaft. - Check belt wheel, motor pulley and shaft. Repair or replace as required.
  2. Valves leaking, broken, carbonized or loose. - Check valves. Clean and replace as required.
  3. Carbon build-up on top of piston(s). - Clean piston(s). Repair or replace parts as required.
  4. Cylinder scratched, worn or scored. - Replace or repair as required.
  5. Piston scratched, worn or scored. - Repair or replace as required.
  6. Defective ball bearings on crankshaft or motor shaft. - Check ball bearings. Replace as required.
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    Gas delivery has dropped off
  1. Clogged or dirty inlet and/or discharge filter - replace filter element.
  2. Gas leaks in piping (on compressor or external piping/system). - Check tubing and connections. Repair or replace as required.
  3. Valves leaking, broken, carbonized or loose. - Check valves. Clean and replace as required.
  4. Automatic condensate drain valve defective - Inspect drain valve. Repair or replace as required.
  5. Piston rings damaged or worn (broken, rough, scratched, excessive end gap or side clearance) - Replace piston rings.
  6. Piston rings not seated, stuck in grooves, or end gaps not staggered. - Clean and adjust piston rings. Replace as required.
  7. Cylinder scratched, worn or scored. - Replace or repair as required.
  8. Piston scratched, worn or scored. - Repair or replace as required.
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    Relief valve vents pressure
  1. Clogged or dirty inlet and/or discharge filter - replace filter element.
  2. Valves leaking, broken, carbonized or loose. - Check valves. Clean and replace as required.
  3. Automatic condensate drain valve defective. - Repair or replace as required.
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    Motor overload trips or draws excessive current
  1. Oil viscosity too high - Drain existing lubricant from frame. Refill with proper lubricant.
  2. Improper line voltage - Improper line voltage - Check line voltage, change lines as required.
  3. Poor contact on motor terminals or starter connections - Ensure good contact on motor terminals and starter connections.
  4. Improper starter heaters - Install proper starter heaters.
  5. Poor power regulation (unbalanced line) - Consult local power company.
  6. V-belt is pulled too tight - Adjust belt tension.
  7. Valves leaking, broken, carbonized or loose. - Check valves. Clean and replace as required.
  8. Automatic condensate drain valve defective. - Repair or replace as required.
  9. Cylinder scratched, worn or scored. - Replace or repair as required.
  10. Piston scratched, worn or scored. - Repair or replace as required.
  11. Connecting rod, piston pin or crankpin bearings worn or scored. - Inspect all. Repair or replace as required.
  12. Defective ball bearings on crankshaft or motor shaft. - Check ball bearings. Replace as required.
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    Moisture in frame or rusting in cylinders
  1. Detergent type lubricant being used - Drain existing lubricant from frame. Refill with specified lubricant.
  2. Extremely light duty cycles - Run compressor for longer duty cycles.
  3. Extremely wet gas - Install dryer.
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    Excessive starting and stopping
  1. Gas leaks in piping (on compressor or external piping/system). - Check tubing and connections. Repair or replace as required.
  2. Pressure switch differential is too narrow Adjust pressure switch to increase differential.
  3. Automatic condensate drain valve defective. - Repair or replace as required.
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    Compressor runs excessively hot
  1. Inadequate ventilation around belt wheel - Relocate compressor or add ventilation.
  2. V-belt pulled too tight - Adjust belt tension.
  3. Wrong belt wheel direction of rotation. - Check motor wiring for proper connections.
  4. Valves leaking, broken, carbonized or loose. - Check valves. Clean and replace as required.
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    Compressor does not come up to speed
  1. Loose belt wheel or motor pulley. Excessive end play in motor shaft. - Check belt wheel, motor pulley and shaft. Repair or replace as required.
  2. Improper line voltage - Improper line voltage - Check line voltage, change lines as required.
  3. Poor contact on motor terminals or starter connections - Ensure good contact on motor terminals and starter connections.
  4. Improper starter heaters - Install proper starter heaters.
  5. Defective ball bearings on crankshaft or motor shaft. - Check ball bearings. Replace as required.
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    Lights flicker and dim when compressor is running
  1. Improper line voltage - Improper line voltage - Check line voltage, change lines as required.
  2. Poor contact on motor terminals or starter connections - Ensure good contact on motor terminals and starter connections.
  3. Improper starter heaters - Install proper starter heaters.
  4. Poor power regulation (unbalanced line) - Consult local power company.
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    Abnormal piston, ring and cylinder wear
  1. Clogged or dirty inlet and/or discharge filter - replace filter element.
  2. Oil viscosity too low - Drain existing lubricant from frame. Refill with proper lubricant.
  3. Oil viscosity too high - Drain existing lubricant from frame. Refill with proper lubricant.
  4. Oil level too low - Add lubricant to frame to bring level up to an acceptable point.
  5. Detergent type lubricant being used - Drain existing lubricant from frame. Refill with specified lubricant.
  6. Extremely wet gas - Install dryer.
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    Gas and/or oil leaking from shaft seal
  1. Shaft seal leaking, broken or improperly seated - Repair or replace as required.
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    Gas and/or condensate leaking through condensate drain system
  1. Automatic Condensate drain valve defective.
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    Excessive noise when compressor is operated
  1. Loose belt wheel or motor pulley. Excessive end play in motor shaft - Check belt wheel, motor pulley and shaft. Repair or replace as required.
  2. Gas leaks in piping (on compressor or external piping/system) - Check tubing and connections. Repair or replace as required.
  3. Valves leaking, broken, carbonized or loose - Check valves. Clean or replace as required.
  4. Automatic condensate drain valve defective - Inspect drain valve. Repair or replace as required.
  5. Connecting rod, piston pin or crankpin bearings worn or scored - Inspect all. Repair or replace as required.
  6. Defective ball bearings on crankshaft or motor shaft - Check ball bearings. Replace as required.
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    Excessive lubricant consumption
  1. Piston rings damaged or worn (broken, rough, scratched, excessive end gap or side clearance).
  2. Piston rings not seated, stuck in grooves, or end gaps not staggered - Clean and adjust piston rings. Replace as required.
  3. Cylinder scratched, worn or scored - Repair or replace as required.
  4. Piston scratched, worn or scored - Repair or replace as required.
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    Compressor is not starting or is very slow to start (motor is humming)
  1. Excess pressure build up in discharge pipe because check valve is plugged or damaged. So check valve becomes a 2-way valve and air comes back into discharge pipe. Pressure switch will release air until it gets to 95psi, then close the release. Next time compressor starts, it will have 95psi back pressure. Replace check valve.
  2. Pressure switch is malfunctioning and not releasing air from compressor properly - Replace pressure switch.
  3. Pressure switch release valve is not working - Replace release valve.
  4. No oil, compressor is seized - Replace compressor.
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    Low air - tools won't work; used to work fine
  1. Element inside the water trap may be plugged - Replace element.
  2. Air filter plugged up - Blow off or replace filter element.
  3. V-Belt too loose and cannot keep up - Replace belt.
  4. Air line leaking - Repair or replace as required.
  5. Pressure switch is malfunctioning and shutting off prematurely - Replace as pressure switch.
  6. If there is a dryer after the compressor, the dryer may be frozen and air is not going through; open air dryer and turn regulator clockwise 1/2 turn at a time to decrease temperature; if water passing through the dryer turn clockwise to cool down.
  7. Filter element in water drain (inside dryer) may be clogged - Replace filter element.
  8. Autodrain plastic float (inside dryer) may not be working due to oil/dirt contentt in air line - Replace float.
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