Air Compressor Will Not Build Pressure

Air Compressor Will Not Build Pressure

Don’t be quick to open the pump if your air compressor will not build pressure. In worse cases, the equipment might not work when there’s air in the compressor tank. I have seen many compression systems with pressure build-up problems. Most times, it’s interesting that these problems don’t share a similar cause. However, this guide will expand your technical skills and explain more ways of resolving pressure issues.

When The Air Compressor Will Not Build Pressure – Troubleshoot!

It’s different when an air compressor runs, but there’s no record of pressure build-up. Operators understand that compressors need pressure adjustment for specific applications.

Also, pressure adjustments might be necessary to improve the energy efficiency of machines.

Normally, an increase of 2 PSI in industrial air compressors consumes one percent of total input power. So, pressure adjustments and buildups affect the efficiency of air compressors.

When the air compressor will not build pressure, what will the operator do?

Problems Due To Air Intake – Check Compressor Intake Valves

The air-intake valve could fail without prior signs. It’s a common experience with mechanical equipment, even when they are new installations.

In technical operations, troubleshooting is the first step in resolving faults. The air compression system uses pressure valves.

Air leaks from drain valves (at the bottom air compression tanks) can cause loss of pressure. Also, an air compressor will not build pressure when the inlet valve doesn’t open completely.

The compressor pump has intake valves and valve plates. Every of its component helps to attain the compression cycle.

Cylinders can’t receive air from intake filters in reciprocating air compressors with defective intake valves. This fault occurs because pistons can’t create any vacuum for a complete compression cycle.

Consequently, the air compressor will not build pressure for the cylinder to close the intake valve.

If there’s a blowback of air, it means your compressor’s intake port is defective. Depending on the design of your compressor machine, uninstall the intake filter and start the ignition. You will feel streams of air coming out of the intake port with your hands.

Problems Due To Defective Valves – Check Compressor Pressure Valve (Flapper)

When pressure valves (flappers) fail, there’ll be an unavoidable loss of torque and pressure. Normally, compressor pistons make upward and downward strokes. When there’s pressure build-up in the cylinder, it forces the pressure valve to open.

This action leads to compression of atmospheric air. Without the pressure valves, air will lose the pressure to flow through air lines into the compression tanks.

It might be a bit technical to diagnose this fault with pressure valves. When pressure valves fail, air will continue its flow from the intake valve with the compression stroke. The only challenge will be when the piston returns to the intake cycle.

There will be a steady loss of air from the compression tank and through the defective pressure valve. Also, there will be back and forth air flows between the piston and intake valves. It’s this unsteadiness that limits pressure build in compression tanks.

When pump valves fail to build-up pressure in tanks, it might not stop the air compressor from running continuously. From the gauge, you’ll notice when there’s no consistent buildup of air pressure.

Air Compressor Won’t Reach Pressure? – Check The Pressure Switch

Is the air compressor slow to build pressure? It might be a failure of the pressure switch. A defective air compressor’s cut-off switch can trigger a fault. When pressure switches fail, air compressors run erratically.

Normally, the pressure switch prevents an air compressor from going past its cut-out (optimum) pressure.  It’s an automatic sensor that protects the air compressor. Air compressors like California Air Tools models start and stop continuously when their pressure differential gets to a slim margin of 1 bar (14 psi).

The differential pressure of compression systems is the variation between the cut-in and the cut-out pressure. If your air compressor won’t reach pressure, the faulty switch needs a replacement.

When air compressors pass their cut-out pressure points, it could lead to overheating of the motor. The air compressor motor should shut down automatically. However, a continuous overheating of the motor might burn your air compressor’s capacitors too.

A typical example is when pressure switches are defective. I had a faulty thermal cut-off switch when my portable Bostitch air compressor will not build pressure. The leakage prevented pressure build-up beyond a certain level. Regardless of how long I ran the air compressor, the problem continued until a pressure switch replacement.

Compressor Not Building Pressure? – Check Pump Piston Rings

It’s the compressor pump that sucks atmospheric air through its intake valve. This unit also has a filter that restricts dust particles from entering into the compressor tank. The rings of a compressor’s pump act as seals. They prevent excess oil from flowing into the compressor’s cylinders.

However, the air compressor not building enough pressure might be from its pump’s defective rings. When rings are defective, pumps will lose pressure and compression strength. This condition often reduces the pump’s efficiency to optimize the production of compressed air.

Usually, technicians either rebuild or replace the pumps with worn seals. Except they can confirm that both pumps and rings are operating very well, the valve plate seal might be the source of the leak.

Another way of detecting loss of pressure from piston rings is when air or oil comes out from the oil fill tube. With regular inspections of air tube fittings, operators can attach them firmly to their rightful positions. However, a piston ring failure might affect other components inside of the cylinder.

When pistons cycle with worn rings, the chance of metal-to-metal contact is inevitable. There are common causes of pressure loss with the air compressor piston stuck inside the combustion engine. During this fault, it’s easy for operators to notice that pressure isn’t building up from the gauge.

Compressor Not Building Pressure
Compressor Not Building Pressure

How To Rebuild An Air Compressor’s Pump

How can you rebuild air compressor pumps? You’ll need high-level technical skills or just hire a technician. Defective seals and other parts of pumps can prevent the system from compressing air.

If the pump won’t compress air, rebuilding the pump with replacement kits (parts and seals) is a surefire way of resolving this issue. Since this process involves a replacement kit, check for products with piston rings, seals, and complete accessories.

What To Do During Air Tank Leaks

Is your Campbell Hausfeld air compressor not building pressure? Normally, the right way of using an air compressor is to drain the tank after each operation. However, operators might forget to shut the drain cover of the compressor tank.

This mistake causes air to drain out of the compression tank and lose pressure. Early discovery and regular inspections with the checklist can ensure that your air tank’s cover is intact. Also, air leaks from compressor tanks can be excessive with corrosion.

Apart from weather effects, the common cause of an air tank’s corrosion is the residual water from condensate. Manufacturers often advise operators to open the tank’s drain valve after using the compressor. The failure to carry out this process regularly will cause accumulations of water and corrosive elements.

Leaks from any part of your tank can cause about a 50% loss of its total compressed air production. It’s easier to fix this chamber when its drain valve has leaks. Otherwise, a hole in the metallic air tank will require a replacement. Don’t forget to check that air tube fittings have tight connections too.

If your air tank has a defective check valve, there will be air leaks from the unloader. Try to confirm if the air leaks continue when the pump is inactive, and replace the check valve. The check valve is an important component that restricts compressed air from back-flowing into the pump.

When this component is defective, the discharge head of the pump will receive a high pressure of air. It will affect the pump’s motor might and stop it from restarting anytime the tank is full. However, the motor will start when the air tank is empty. To resolve this fault, replace the check valve immediately.

Other factors that support air tank leaks include the lifespan, low-quality material, and loose hose fittings.

Central Pneumatic Air Compressor Not Building Pressure?

Valves of compression systems are important. The safety valve protects the system when it reaches a level of excess pressure. It triggers the release of excess air and depressurizes the tank when pressure switches fail.

So, the safety (relief) valve of pneumatic systems is the last resort during threats of excess pressure build-ups. My experience with a Porter Cable compressor not building pressure was quite revealing. The fault from a defective reed valve prevented the system from getting sufficient pressure.

Air passed through the intercooler safety valve instead of going through its second-stage piston. Fluctuating between 40 to 80 PSI wasn’t a good sign of a functional air compressor. However, reed valve replacements at the top of each cylinder were the solution.

If your air compressor has this fault, unscrew the cylinder’s cap, and disassemble the unit. Replace the reed valves, gaskets, and fix the head plates on the cylinder firmly.

Craftsman Air Compressor Not Building Pressure Because Of A Belt Malfunction?

A Craftsman 3 Gallon air compressor won’t build pressure, and the fault was from its belt. It was very easy to detect because of my previous experience when a Husky air compressor won’t build pressure. However, this loss of pressure build-up is common with belt-driven compressors.

Don’t check the belt without switching off the equipment. Loosen the belt guard’s rear section, and dismantle the motor’s mounting bolts. It might need some adjustments or a replacement of the belt.

To Install A New Belt(s):​​​​​

  • Slide the motor towards the pump
  • Detach the old belt from its pulley
  • Attach a new belt(s)
  • Return the motor to its original position and tighten its mounting bolts
  • You might need to adjust the belt and get a proper tension level
  • Don’t forget to reinstall the compressor’s belt guard.

Do A Pump-Up Test:

The pump test is an air compressor maintenance process that detects leaks. Follow these steps to do a general pump test:

  • Open the drain valve (at the bottom of your air tank); release the residual condensate and air.
  • Close the drain valve and the tank’s outlet valve to allow only air intakes
  • Pre-set the recommended cut-in and cut-out pressures with the switch.
  • Run the air compressor and track the time it takes the tank to reach a full state.
  • When it gets to the cut-out pressure, we expect the air compressor to stop automatically.
  • As you have learned from this guide, check every part of the air compressor to detect a leak and oily residues. 


Every operator has to be careful when an air compressor will not build pressure. Modern compressor brands like Makita and Dewalt have sensors that activate safe shut down modes. However, operators can rely on built-in systems in air compressors to prevent costly damages. Instead, our air compressor troubleshooting techniques in this guide can help to detect loss of pressure.

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