Experiencing issues with your industrial chillers? Most chiller problems follow recognizable patterns, but it can still be difficult to determine what is going on. Since industrial process chillers run around the clock, the cost of downtime or cooling issues can add up fast.
Below is a guide to the most common issues we see across industrial chillers, along with practical troubleshooting steps to help you get back online.
Running a glycol-based system and dealing with concentration, flow, or fluid-quality issues instead? See our guide, Troubleshooting Common Problems with Glycol Chillers.
1. Chiller Won’t Start
Potential Causes:
- Blown fuse or tripped circuit breaker
- Loose or damaged wiring at the control panel or contactors
- Refrigerant pressure too low, tripping a built-in safety lockout
- Faulty control board, relay, or sensor preventing startup
Troubleshooting Steps/Tips:
- Check the power source: confirm incoming voltage and verify the disconnect and breaker are on.
- Review the controller: check for active fault codes before attempting a restart.
- Check refrigerant pressure: low charge can trigger a low-pressure lockout before the compressor ever engages.
- Inspect wiring: look for loose terminals, corrosion, or burnt connections at the control panel.
2. Chiller Not Reaching Setpoint or Cooling Requirements
Potential Causes:
- Heat load exceeds the chiller’s rated capacity
- Low refrigerant charge from a slow leak
- Dirty or blocked condenser coils (air-cooled) or fouled condenser tubes (water-cooled)
- Degraded process fluid reducing heat transfer efficiency
- Incorrect setpoint or controller configuration
Troubleshooting Steps/Tips:
- Confirm the setpoint: verify the controller is programmed correctly and hasn’t drifted from the intended value.
- Compare load to capacity: verify the process heat load hasn’t grown beyond what the unit was sized for. If it has, it may be time for a new process chiller.
- Inspect and clean the condenser: dirty coils or tubes are one of the most common causes of reduced cooling capacity.
- Check refrigerant pressures: readings outside the expected range can point to a leak.
- Evaluate the process fluid: contaminated or degraded fluid loses its ability to transfer heat effectively.
3. High-Pressure or High-Temperature Alarms Keep Triggering
Potential Causes:
- Dirty condenser coils restricting heat rejection
- Failed or underperforming condenser fan motor (air-cooled units)
- Restricted condenser water flow (water-cooled units)
- Refrigerant overcharge or non-condensables trapped in the circuit
- Faulty pressure or temperature sensor giving a false reading
- Poor condenser airflow due to inadequate ducting or an undersized mechanical room results in heat recirculation, causing high-pressure faults or high-pressure safety switch trips.
Troubleshooting Steps/Tips:
- Verify condenser water flow: for water-cooled units, confirm the flow rate and check for scale that may restrict the tubes.
- Validate sensor readings: cross-check with a secondary probe before condemning a component based on a single reading.
- Clean the condenser: dirty coils are a leading cause of high-pressure trips — clear debris and confirm airflow is unobstructed.
- Check fan operation: confirm all condenser fans are spinning and drawing proper airflow.
- Reset and reprogram: reset the power cycle the unit and confirm setpoints are correct if the alarm doesn’t correspond to an actual condition. You may need to reprogram setpoints if you find issues.
- Note: correct any ventilation or ducting deficiencies and maintain the required clearances around the unit.
4. Low Flow Alarms or Flow Switch Trips Are Happening
Potential Causes:
- Clogged strainer or filter restricting pump inlet flow
- Partially closed or stuck isolation valve
- Pump wear, cavitation, or impeller damage
- Air trapped in the process loop
Troubleshooting Steps/Tips:
- Check the strainer first: a clogged evap or Y-strainer is the single most common cause of low-flow trips and the easiest to fix.
- Verify valves are open: confirm all isolation valves in the loop are fully open.
- Listen to the pump: cavitation noise, vibration, or inconsistent flow often points to impeller wear.
- Bleed the system: if this is a closed-loop system, find the highest point in the piping and bleed from an air vent valve. If the system is open to the atmosphere (has a tank), keep trying to run until air is purged out through the tank.
5. Chiller is Short-Cycling
A quick note on why this matters more for some chillers than others: fixed-speed compressors only run fully on or fully off, so an oversized or slightly-off system is forced into frequent cycling, which is one of the fastest ways to wear out a compressor.
Delta T Systems’ variable speed compressors modulate output to match real-time demand instead of cycling on and off, which reduces this specific failure mode by design.
Potential Causes:
- Chiller is oversized for the actual process load
- Refrigerant undercharge causing the compressor to trip on protection
- Dirty condenser triggering repeated high-pressure trips
- Faulty pressure or temperature sensor causing erratic on/off behavior
Troubleshooting Steps/Tips:
- Confirm sizing: verify the chiller is properly sized for the application. Chiller capacity exceeds the process load, causing the unit to reach minimum compressor speed before the load can absorb the available cooling.
- Test sensors: a failing pressure or temperature sensor can cause the controller to cycle the compressor unnecessarily.
- Check refrigerant charge: undercharged systems often trip on low-pressure/freeze point protection during normal operation.
- Inspect the condenser: clear any buildup that could be triggering repeated high-pressure faults.
6. Chiller is Making Unusual Noise or Vibration
Potential Causes:
- Worn pump or compressor bearings are rattling
- Loose or unbalanced condenser fan blades making noise
- Equipment not properly isolated from the mounting surface is causing vibrations
- Cavitation from restricted flow or air in the loop
Troubleshooting Steps/Tips:
- Isolate the source: determine whether the noise is coming from the pump, compressor, or fans before assuming the worst.
- Rule out cavitation: noise that correlates with a flow alarm often points back to a restriction rather than a mechanical fault.
- Check fan balance and mounting: loose fan blades or hardware are a common and inexpensive fix.
- Verify vibration isolation: confirm the unit is mounted on proper isolators, especially on upper floors or near occupied space.
7. Control Board, Sensor, or Fault Code Issues
Potential Causes:
- Failed temperature or pressure sensor
- Loose or corroded wiring connections
- Controller or PLC malfunction
- Intermittent, hard-to-reproduce fault codes with no clear mechanical cause
Troubleshooting Steps/Tips:
- Cross-check readings: use a secondary probe or gauge to confirm whether a fault reflects a real condition or a sensor failure.
- Inspect wiring: loose or corroded connections at the sensor or terminal block are a frequent source of erratic readings.
- Log the fault pattern: note when and under what conditions the fault occurs — this speeds up diagnosis significantly, whether in-house or over the phone with a technician.
- Call before you swap parts: our team can often help interpret a fault code and narrow down the cause remotely before a part is replaced unnecessarily.
This is why Delta T Systems chillers include remote diagnostics, so our team can review real-time system data over the phone and help you diagnose a fault code before scheduling a technician visit. This saves everyone time, travel, and money.
Oftentimes, chiller downtime is happening because there are no regular preventive maintenance steps in place. Below is what we recommend for minimizing chiller downtime.
Proactive Tips to Minimize Chiller Downtime
Most of the issues above are preventable with routine attention. We recommend a tiered schedule:
- Weekly: Check fluid levels, inspect for leaks, and monitor for active alarms.
- Monthly: Clean or inspect strainers, check electrical connections, and listen for abnormal pump or fan noise.
- Quarterly: Clean condenser coils or tubes, verify refrigerant pressures.
- Annually: Schedule a comprehensive inspection by a certified technician, including refrigerant charge verification and sensor calibration.
For a deeper walkthrough of maintenance schedules and cleaning frequency, see our full guide: Preventive Maintenance Tips for Long-Lasting Chiller Performance.
Need Chiller Service Support? We’re Happy to Assist!
At Delta T Systems, our mission is reliable and responsive service. If you use our process chillers and encounter an issue you can’t resolve on-site, our experienced technical support team is just a phone call away — real support, no robots.
Explore our full line of air-cooled, water-cooled, portable, and packaged process chillers, or see how our chillers compare to the competition. For plant-wide cooling infrastructure, also see our Industrial Central Chillers.