Kaeser air compressors are industrial, rotary screw compressors. Like all compressors though, they can malfunction, and one of the most common problems is low air pressure. When an air compressor is not building up enough air pressure there could be one or more reasons why it won’t build up enough pressure. 

A Kaeser air compressor that doesn’t build up enough pressure could be due to faulty hoses or connections, internal reed valves malfunctioning or going bad, or even mechanical failure. Some fixes can be relatively simple, while others will require the expertise of trained professionals.

Low Pressure On Kaeser Air Compressor

There can be many different reasons a Kaeser air compressor doesn’t build up or hold enough air pressure. The first thing to do is check for the simplest solutions, and work down to more complicated possibilities. It could be something as simple as air demand is too high and the system needs to be recalibrated. 

Below are common issues that can be associated with low pressure on a Kaeser air compressor and common fixes. 

Air Leaks in Hoses or Connections

The first thing to do is check all the hoses and connectors to see if there are faulty connections or pinhole leaks that constantly lose air pressure. Run through every hose to make sure there are no problems there. Then check each connection; sometimes O-rings wear out and need to be replaced. 

Inspect Filters

Dirty or clogged filters can cause significant airflow issues. It’s a simple inspection and easy fix if there are dirty filters. 

Check inlet filters and compressed air filters if there are any. These can easily be overlooked and forgotten over time as they are such innocuous parts, but clogged filters can really restrict airflow. 

Clean them out if they are reusable filters, or replace them if they are disposable. 

Check The Pressure Relief Valve

Assuming all the hoses and connectors check out but the machine is still not holding pressure, check the pressure relief valve. These valves can get a lot of use and even with compressed air dryers, moisture can still condense inside. The moisture could cause rust problems with the pressure relief valve, or it may simply malfunction.

The simple fix is to replace the valve as necessary. 

Examine The Pressure Gauge

While a faulty pressure gauge is uncommon, this can still happen at times. The machine may be running perfectly, but the gauge is showing low pressure. 

When compressed air tools are working properly but the gauge still shows a low pressure reading, chances are the pressure gauge is malfunctioning. There could be a clog in the port or a problem with the mechanics inside. Simply replace the gauge and see if that fixed the problem. 

Check the Inlet Valve

The inlet valve on a rotary screw air compressor regulates how much air is pulled into the compressor. These valves almost always are open or closed. When closed, even if the compressor is still running, air will not be allowed in until it opens back up. 

The inlet valve could freeze in the open or closed position and cause problems with pressure in the air compressor. If the valve is stuck closed, the compressor will not be able to compress air, no matter how much the air compressor runs, there will be no pressure in the tank. 

If the machine is running but there is no air pressure, there could be a problem with the inlet valve. When inlet valve malfunction is suspected, it needs to be replaced. 

Compressor Belt Problems

The belts run from motor to pulley and help to turn the parts that actually compress the air. Over time belts can stretch causing them to slip or become less effective, or they can break completely. 

While the machine is turned off, check the belts on the Kaeser air compressor to see if they are still working properly. If the belts are loose, can be wiggled easily or broken, replace them as needed. 

compressor belt

Dryer Heat Exchange Problems

The dryer heat exchange is a part of the air compressor that alters the temperature of the compressed air. When air is compressed, a byproduct is heat. To prevent hot air from flowing to the tools attached to the air compressor, a heat exchange is implemented to help cool the air down. 

Sometimes the heat exchange can get clogged with dirt, dust, and debris. When this happens it can cause low pressure because the motor has to run harder, and the air can’t be compressed as much. 

Check the thin foils occasionally for dirt and dust buildup and gently clean as needed. A clean heat exchange, as well as clean filters, can help equipment run smoothly.

Air Demands Could Outpace Output

Low air pressure on a Kaeser air compressor could be as simple as supply and demand. There could be an excessive amount of use on one machine and it’s not able to keep up. 

Are there a lot of tools working on one machine at the same time? Check the usage of the machine. It could be that one or two tools need to be set up on a different compressor, or used at another time. 

In some instances, simply increasing the air pressure on the compressor would be enough to fix the problem. 

air dryer with pressure gauge

Check the Pressure Switch

Is the pressure switch set too low? Is the pressure differential too wide or narrow to keep up with demand? These may need to be adjusted. 

On Kaeser compressors, the pressure settings can be set at the display. Once you gain access to the menu, go to CONFIGURATION, from there go to PRESSURE CONTROL, then to PRESSURE SETTINGS. 

This will open up the SET POINT PRESSURE menu. Now simply set the cut-in, cut-out, and pressure differential. 

There Could be a Solenoid Malfunction

Several problems can go wrong with a solenoid valve. When this part malfunctions pressure can be lost, or the compressor won’t hold pressure. Sometimes a solenoid can be easily fixed or cleaned, but other times it may have to be replaced. 

One of the most common problems for a solenoid malfunction is dirt, particles, or debris buildup preventing proper operation. Some of the most common particles that cause problems with solenoid valves are rust, cuttings, dirt, and even pieces of teflon tape. 

Even a tiny amount can cause a solenoid to work improperly. To fix these issues, carefully open up the solenoid valves and gently clean or rinse the parts free of debris, dry them completely, and put the solenoid valve back together. 

Other problems with a solenoid valve could be damaged or malfunctioning membranes, O-rings, or seals. Check to make sure each of these parts is not damaged, and replace them as needed. Even small imperfections could cause significant pressure loss. 

Coil damage could be a culprit in the solenoid valve as well. If there are any cracks or chips in the housing, replace the coil. Also, if there are no audible clicks when the solenoid is engaged, it will need to be replaced as there could be internal issues.  

Finally, if everything else looks like it’s in good working order on the solenoid valve, check the power connections. Make sure all wiring is correct and undamaged, it’s attached properly, and has an uninterrupted power supply. 

Look For Mechanical Issues

If the air compressor still does not create or hold pressure after checking all the above parts and possible problems, there may be a mechanical issue. There could be a problem with the compressor motor, or it could be damaged rotors. 

If mechanical issues are suspected, a qualified Kaeser air compressor technician should take a look at the air compressor. They have proper personnel that knows these machines inside and out who can diagnose and repair whatever is wrong with the air compressor. 

Kaeser Compressor Fault Codes

There are dozens of possible fault codes that can come up on a Kaeser air compressor during routine operation. Simply check the owner’s manual to see a complete list of all possible codes that can be thrown.

Most of these codes will probably never be encountered in a lifetime, and many others are minor issues that can be fixed relatively easily. Below are some of the more common codes that could be seen during normal operation and maintenance procedures and how to fix them. 

Low Pressure at Point of Use

A low pressure code can happen to the best of machines, even when maintenance is strictly regimented. Sometimes parts simply give out or break. If this code shows up on Kaeser air compressors, go through the above list to find out the cause and how to fix it. 

Low Pressure at Compressor Discharge

This code can be caused by worn or broken valves. Check to see if any valves need to be repaired or replaced. 

Check the air pressure switch setting. Was it adjusted lately, or does it need to be adjusted? The way to fix the Low Pressure At Compressor Discharge code is to adjust the pressure settings back to the manufacturer’s suggested settings.

Water in the Lines

This code is self-explanatory, though the causes could be many. The air coming into the compressor could be too humid, the air dryer could malfunction, or there could be a faulty air/oil separation element. 

First, the tank needs to be drained of all air and water. If the environment where the compressor is drawing in air is too humid, an air dryer may need to be installed, or if the machine already has one, it will need to be serviced, or possibly a larger air dryer may be necessary. 

If the problem has been caused by a faulty air/oil separation system, the element needs to be replaced. 

Dirt or Debris in Lines

Rust inside the air compressor could cause this issue, especially if water in the lines was previously a problem. If this code appears, turn off the air compressor, drain the air and clean out the lines. In extreme cases, the hoses may have to be replaced. 

Normal wear can also cause debris in the lines. If this is a problem, filters should be installed at the point of use. If filters have already been set into place, they should be inspected. The filters could be clogged or damaged. 

Excessive Service to Load/Hour Ratio

When this code shows up on Kaeser air compressors, it means the compressor is sitting in idle mode for too long. It may mean the machine is on but not being used enough, or the idle time needs to be adjusted. 

Minimize the amount of time the air compressor is spending in idle mode by adjusting the idle time according to the manufacturer’s suggestions. 

An improper pressure switch setting could throw this code as well. Again, refer to and follow the owner’s manual or manufacturer’s suggestions. 

Elevated Compressor Temperature

If this code is showing on the display, the unit needs to be shut off immediately before major damage can occur. Causes of elevated temperature include restricted airflow, water flow, or fluid flow, low fluid levels, or excessive ambient temperatures. 

Check filters to make sure they are not clogged, then clean or replace them as needed. Clean the heat exchanger if it has become clogged if water flow is restricted. Remove fluid restrictions if there are any found, and for low fluid levels, check all fluids and add more as needed. 

Check the owner’s manual to find out the max safe operating temperature for the air compressor. If the ambient temperature is suspected to be a cause of the elevated compressor temperature, a fan or air cooler may need to be installed.


Over time and under normal working conditions a Kaeser air compressor is likely to have a few problems during its lifespan. If it’s not building or holding pressure, it could be as simple as a leaking hose or connection, or something as major as broken rotors.

Most times these machines malfunction because of dirt or water buildup. Proper, routine maintenance can help to prevent most issues with these air compressors.