Air Compressor Troubleshooting Guide

Why having troubleshooting knowledge for an air compressor is a good thing

Having an air compressor at home or at a job site is a great way to speed up the laborious tasks in hand. The use of pneumatic tools makes it possible to cut, chisel, hammer, paint, trim, and also undertake certain carpentry works and automotive repairs at a professional level. High quality air compressors such as the ones from reputed manufacturers like Makita, Senco, and Dewalt are built to last many years and provide you commendable service during that period.

However this does not guarantee zero failures or damages. Environmental factors, coupled with overuse, and overloading can result in a drop in the level of performance from the air compressor, eventually culminating in total loss of operations in some circumstances.

Air Compressor Troubleshooting Guide

Having a basic knowledge of the troubleshooting for an air compressor can be of immense help as this will help you rectify some minor faults without having to wait for the intervention of a professional electrician or mechanic. Moreover, if the issue is a major one you will be in a better position to inform the service center what the problem and thus get it rectified in shorter time.

Various common air compressor issues and their solutions

Here we take a look at some of the common issues faced while operating an air compressor, the plausible reasons behind their occurrence and some basic steps to take care of these problems.

Problem: The compressor does not operate

Likely causes and their solutions:

  • There is no electrical power: Switch on the power supply and press the reset button
  • The oil level is low: Check the oil level and if necessary, get a replacement
  • Pressure switch failing to make contact: See the adjustment on the pressure switch
  • Tank pressure is below the specified cut-in pressure: Check the adjustment of the pressure switch and replace with one that has a lower cut-in PSI rating

Problem: Excessive noise during operation

Likely causes and their solutions:

  • Loose fitting of the pulley, clamps, cooler, belt guard, belt, flywheel, or other similar accessories: If you find any loose ends, simply tighten them
  • Low oil level in the crankcase: There could be a possibility of damage to the bearings so check them. In case of low oil levels, get them replenished
  • Piston is making contact with the valve plate: Remove the head of the compressor cylinder and check for the presence of foreign matter on the top of the piston. You could also add in a new gasket before reassembling the head
  • Loose floor mounting of the compressor: Tighten all bolts on the air compressor. Replacing the vibration pads won’t be a bad idea as well
  • Defective crankcase: Either replace it or get it repaired
  • Excessive end play of the crank: The crank should be adjusted and shimming done on it properly

Problem: Knock happens on the same cycle as RPM

Likely causes and their solutions:

  • There is some problem with the main bearings: The main bearings need to be replaced
  • Problem with the connecting rod bearings: Replacing the connecting rod is the only solution
  • The flywheel is loose: Tighten the flywheel

Problem: Knock occurs when the compressor is loading

Likely causes and their solutions:

  • There could be some issue with the connecting rod bearings: The connecting rod needs to be replaced
  • The wrist pins and wrist pin bearings are causing problems: The piston assembly needs to be replaced
  • The nut on the connecting rod is loose: The connecting rod nut has to be tightened

Problem: Presence of milky oil in the oil reservoir

Likely cause: In all likelihood water has been entering the oil reservoir because the compressor is being operated in a highly humid environment.


  • Connect the intake air pipe to a less humid air source
  • Undertake servicing of the unit. This could include cleaning or replacing the air cleaner element, or changing the oil. If you do change the compressor oil, the frequency may have to be increased with every 500 operating hours or 45 days being the recommended frequency
  • Drain the reservoir tank of the compressor daily

Problem: The compressor is consuming excessive oil

Likely causes and their solutions:

  • Air intake has been restricted: The air filter has to be cleaned or replaced
  • There are oil leaks in the compressor: The gasket may have to be replaced if tightening the bolts does not yield positive results
  • The piston rings have worn out: The piston rings have to be replaced
  • Oil of inappropriate viscosity is being used: Drain out the oil and replace it with compressor oil of appropriate viscosity
  • The compressor is tilted too far at an angle: Align the compressor to the same level. Use of vibration pads will help you out in this case

Problem: Oil is entering the discharged air

Likely causes and their solutions:

  • Air intake of the compressor is restricted: The air filters should be cleaned or replaced
  • The piston rings have worn out: The piston rings have to be replaced
  • There is an excess of oil in the compressor: Drain out the oil to the full mark on the sight gauge
  • Oil with wrong viscosity is being used: Check the viscosity of the oil being used as replace it if necessary
  • The piston rings have been installed upside down: The crankshaft should be replaced

Problem: Vibrations occur on the compressor

Likely causes and their solutions:

  • The mounting bolts are loose: You need to tighten the mounting bolts
  • The compressor has not been mounted properly: Level the compressor such that all its feet are touching the ground before tightening them in
  • Misalignment of the pulley and flywheel: There needs to be a realignment of the pulley and flywheel
  • The compressor belts are loose: The belts have to be tightened
  • The crankshaft is bent: The crankshaft needs to be replaced

Problem: Air blows out from the inlet

Likely cause: The first stage inlet valve is broken.

Solution: The valve plate assembly needs to be replaced.

Problem: Fuses blow out repeatedly

Likely cause: The wrong fuse size is being used.

Solution: Ensure that the fuses are of a proper ampere rating. If not, they have to be replaced.


Air compressors represent modern workhorses as they are capable of driving numerous mechanical equipments across places. So to face an extended downtime due to technical glitches is not something any owner would love to be faced with. Fortunately, a number of these issues are minor ones and can be rectified easily by referring a troubleshooting guide. However, for more complex problems consulting and seeking the help of a qualified professional is always advisable and recommended.

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