High Pressure Alarm on Your Chiller? Common Causes and Quick Fixes

Industrial chillers are designed to operate within a defined pressure range. When a high-pressure alarm is triggered, it indicates that heat is not being discharged efficiently or that control components are not functioning correctly. If left unresolved, repeated high-pressure trips may result in compressor failure, reduced cooling capacity, or unplanned downtime.

If you are dealing with multiple fault symptoms or want a broader troubleshooting reference, this guide may also be helpful:

What Are the Common Chiller Faults and How to Troubleshoot Them?

For compressor-specific fault analysis, you can also refer to:

Common Faults And Solutions For Chiller Compressors

Common Causes of High Pressure Alarms in Chillers

1. Dirty Condenser or Poor Heat Dissipation

A contaminated condenser is one of the most common reasons for high-pressure alarms. When dust, scale, or debris blocks heat exchange surfaces, condensing pressure rises rapidly.

Quick Fix:

• Clean condenser coils or condenser tubes thoroughly
• For air-cooled chillers, ensure ambient air temperature remains below 40°C
• For water-cooled chillers, maintain cooling water temperature below 35°C

2. High-Pressure Switch Trip or Reset Required

In many cases, the high-pressure alarm is caused by a high-pressure switch trip, which acts as a safety protection to prevent compressor damage.

Quick Fix:

• Identify and eliminate the root cause of pressure rise
• Press the high-pressure reset switch
• Restart the compressor after confirming normal operating conditions

3. High-Pressure Switch Malfunction

A faulty or aging high-pressure switch may trigger false alarms even when system pressure is within the normal range.

Quick Fix:

• Inspect the high-pressure switch for wiring issues or mechanical failure
• Replace the high-pressure switch if abnormal readings persist

4. Excessive Refrigerant Charge

Overcharged refrigerant increases condensing pressure and reduces heat transfer efficiency. This condition is often overlooked during maintenance or refrigerant replenishment.

Quick Fix:

• Check refrigerant charge quantity against manufacturer specifications
• Recover excess refrigerant to restore normal pressure levels

5. Cooling Water Pump or Cooling Water System Failure

For water-cooled chillers, insufficient cooling water flow due to pump failure, clogged pipelines, or system blockage can cause rapid pressure escalation.

Quick Fix:

• Inspect the cooling water pump operation
• Repair or replace the pump if flow is insufficient
• Check filters, valves, and piping for blockages

Preventive Measures to Avoid High-Pressure Alarms

1. Perform regular condenser cleaning and inspection
2. Monitor ambient temperature and ventilation conditions
3. Maintain proper refrigerant charge levels
4. Inspect pressure switches during routine maintenance
5. Ensure stable and sufficient cooling water circulation

Preventive maintenance significantly reduces the risk of repeated alarms and extends chiller service life.

Frequently Asked Questions (FAQs)

Q1: Is it safe to keep running a chiller after a high-pressure alarm?

No. Repeated operation under high pressure can damage the compressor and internal components.

Q2: Can a faulty high-pressure switch cause nuisance trips?

Yes. A malfunctioning switch may trigger alarms even under normal operating pressure.

Q3: How do I know if refrigerant overcharge is the issue?

Abnormally high condensing pressure combined with reduced cooling efficiency often indicates overcharging.

If the refrigerant is overcharged, please refer to this article: How to Safely Remove Excess Refrigerant in Chillers Step by Step

Q4: Should I reset the alarm without checking the cause?

No. Always identify and resolve the underlying issue before resetting the system.

If you are unsure how to diagnose a high-pressure alarm—or whether it is related to cooling conditions, refrigerant charge, or control components—feel free to contact Nanjing Hengde.

By providing details such as your application, cooling capacity, operating temperature, voltage, and any special requirements, our engineers can help you identify the cause and offer a suitable industrial chiller solution with a clear quotation.