A commercial chiller rarely fails without warning. The seven patterns described here show up weeks or months before shutdown, and every one of them is something a plant engineer or facility manager can identify without waiting for a service call. Samco Facilities Maintenance has serviced centrifugal, screw, and scroll chillers across Southeast Michigan since 1997. If your chiller is showing any of these signs, call (734) 838-6300.
Why Chiller Failures Start Weeks Before the Shutdown
A chiller that fails without warning is almost always a chiller that was giving warnings nobody acted on. The indicators are rarely dramatic. Approach temperature creeps up two degrees. Compressor discharge pressure reads a few PSI higher than last month. A vibration sounds slightly different than March. On its own, each reading looks minor. Together they tell a story about a system losing its ability to transfer heat and compensating by working harder, accelerating wear on every mechanical component in the circuit.
The cost of ignoring early warnings is severe. A centrifugal chiller overhaul in 2026 runs $30,000 to $80,000 depending on size and condition. Full replacement for a 200 to 400-ton water-cooled unit runs $150,000 to $400,000 installed. Compare that to a tube brush and eddy current test totaling $3,000 to $6,000 that would have extended equipment life by three to five years.
Michigan buildings that rely on central plant chillers have very little tolerance for unplanned downtime. A manufacturing facility in Auburn Hills running injection molding cannot substitute window units when the chiller fails. The financial exposure from a chiller failure is rarely limited to the repair bill alone.
The Seven Warning Signs Plant Engineers Should Act On
Treat any one of these indicators as a reason to schedule an inspection, not a reason to keep monitoring:
- Rising approach temperature. Approach temperature is the difference between the leaving chilled water temperature and the refrigerant evaporating temperature. Normal approach is 1 to 3 degrees Fahrenheit. When approach starts climbing above 4 to 5 degrees and no load change explains it, the evaporator tubes are fouled. Every degree of additional approach adds roughly 1 to 2 percent to compressor energy draw and accelerates wear.
- Condenser pressure trending higher over successive logs. Condenser pressure that climbs across weekly data with no change in ambient conditions or load points to fouled condenser tubes or non-condensables in the refrigerant circuit. Both are fixable early. Neither fixes itself.
- Compressor motor drawing higher amperage at the same load point. Pull the amp log from the BAS and compare the current week to three months ago at the same load. An increase of 5 percent or more at matched conditions is a red flag. The compressor is working harder for the same result, which means efficiency is down and something mechanical is degrading.
- Unusual vibration or noise during start or steady state operation. Centrifugal chillers run smooth. Any new knock, rattle, or grinding that was not there last season belongs on a service report immediately. Bearing wear and impeller clearance issues are inexpensive early and very expensive after a catastrophic failure.
- Refrigerant charge loss between service visits. A chiller that needed refrigerant at the last PM visit and needs it again at the next one has a leak. Adding refrigerant without detecting and repairing the leak is not maintenance. It is also a regulatory violation under Section 608 for systems above the applicable threshold.
- Oil analysis showing metal contamination or elevated acid number. Annual oil analysis is cheap insurance on large chillers. Metal particles mean bearing or rotor wear. An elevated acid number means moisture or refrigerant contamination in the oil circuit. Either finding warrants immediate follow-up service.
- Chiller cycling on safety trips more frequently than baseline. Modern chiller controls log every safety trip with a timestamp and cause code. Pull that log. A chiller tripping on high pressure, low pressure, or motor overload more often than its historical baseline means operating conditions have moved outside normal range. The answer is not always obvious from the trip code alone.
The Michigan Angle: Great Lakes Water Chemistry and Tube Fouling
Hard water across Wayne County and Oakland County fouls chiller tubes faster than national averages. Detroit municipal water and well sources across Washtenaw and Macomb counties deliver calcium and magnesium hardness that builds scale on heat transfer surfaces faster than a facility in Atlanta or Phoenix would see.
Scale on chiller tubes acts as an insulating layer. A 1/32-inch scale deposit reduces tube heat transfer efficiency by roughly 10 percent. A 1/16-inch deposit reduces it by 30 percent or more. That loss shows up as a rising approach temperature, which then drives up compressor work, which drives up energy cost and mechanical wear. The fix is chemical treatment of the condenser water loop plus mechanical tube brushing at defined intervals. The frequency depends on your water chemistry, not a national service interval table.
A Novi office campus with a 300-ton water-cooled chiller on untreated city water will foul tubes noticeably within 18 months. A building on a proper water treatment program can extend tube cleaning intervals to 24 to 36 months. The treatment program costs less per year than one cleaning visit. Skipping water treatment to save a line item almost always increases total annual spend.
Eddy current testing is the right tool for tube inspection. A borescope shows surface condition. Eddy current reports wall thickness and early-stage pitting. For chillers over 15 years old in Michigan municipal water areas, annual eddy current testing is the Samco standard regardless of visible scale conditions.
A Pre-Shutdown Inspection Checklist
If your chiller is showing one or more of the warning signs above, run this checklist before calling for emergency service. It does not substitute for a professional inspection, but it organizes the information a technician will need and may identify additional contributing factors:
- Pull and log the last 30 days of BAS trend data for leaving chilled water temp, entering condenser water temp, compressor discharge and suction pressure, and motor amps at matched load points.
- Check the chiller controller fault log for any logged safeouts, trip codes, and timestamps within the last 90 days.
- Verify condenser water flow rate at the pump. Low flow is a common cause of rising condenser pressure that is sometimes as simple as a partially closed valve or a clogged Y-strainer.
- Inspect the cooling tower or fluid cooler for basin fouling, scale on fill media, and fan operation. A degraded tower will push entering condenser water temperature up and stress the chiller even when the chiller itself is in good condition.
- Check refrigerant sight glass for bubbles at steady-state operation, which indicates low charge, and for moisture indicator color if your sight glass includes one.
- Review the oil level and color via the sight glass or oil level indicator. Dark or milky oil in a chiller is an immediate service call trigger.
- Listen at the compressor section during a normal start cycle and note any sounds that differ from the unit’s normal profile.
How Samco Services Centrifugal and Screw Chillers
Samco Facilities Maintenance runs chiller maintenance programs for commercial and industrial customers across Southeast Michigan. Our EPA 608 Universal certified and NATE certified technicians work on centrifugal, screw, and scroll chillers from Carrier, Trane, York, and McQuay across Wayne, Oakland, Macomb, and Washtenaw counties.
A Troy Class A office building we have serviced since 2007 called us in after their 250-ton Carrier centrifugal showed rising approach temperature on two consecutive quarterly visits. Our eddy current test found early-stage pitting on 12 condenser tubes. We retubed those sections, adjusted the water treatment program, and documented the work. That chiller is now in its 18th year of service and still operating within original design parameters. Acting at the first warning prevented a $60,000 compressor repair.
Our chiller service scope includes full operating parameter trending, refrigerant circuit inspection, oil analysis, tube inspection and cleaning, condenser water flow verification, and a written report with capital planning notes. To schedule a chiller inspection, call (734) 838-6300 or visit our commercial HVAC services page. Learn more about our preventive maintenance programs and manufacturing facility service capabilities.
Frequently Asked Questions
What are the warning signs a commercial chiller is about to fail?
The seven most reliable indicators are: rising approach temperature, condenser pressure trending higher at matched load, compressor motor drawing elevated amperage, unusual vibration or noise, refrigerant charge loss between visits, oil analysis showing metal or acid contamination, and increased safety trip frequency in the controller log. Each one warrants an immediate service call rather than continued monitoring.
How often should a centrifugal chiller be serviced?
Annual full service is the baseline for centrifugal chillers, including refrigerant circuit inspection, oil analysis, tube inspection, and full operating parameter logging. Buildings in Michigan municipal water service areas should include condenser tube brushing annually and eddy current testing every two years due to hard water fouling rates. Chillers over 15 years old benefit from semi-annual inspection visits.
What is a normal chiller approach temperature?
Normal approach temperature on a well-maintained water-cooled chiller is 1 to 3 degrees Fahrenheit. Approach above 4 to 5 degrees with no load change explanation indicates evaporator tube fouling. Approach above 6 to 8 degrees is an urgent service condition. Air-cooled chillers have different approach profiles, typically 8 to 15 degrees at design conditions, but the trend direction matters more than the absolute number.
Can you service both air cooled and water cooled chillers in Metro Detroit?
Yes. Samco services both air-cooled and water-cooled centrifugal, screw, and scroll chillers across Metro Detroit, including Wayne, Oakland, Macomb, and Washtenaw counties. Our technicians are EPA 608 Universal certified and trained on major chiller brands including Carrier, Trane, York, and McQuay. We handle routine PM, refrigerant circuit service, tube inspection, and capital planning assessments for both chiller types.
Ready to Schedule a Chiller Inspection?
If your chiller is showing rising approach temperatures, trending higher amp draw, or any of the seven warning signs in this guide, schedule service now. Samco Facilities Maintenance serves commercial and industrial facilities across Southeast Michigan, including Livonia, MI and surrounding Wayne and Oakland county areas. We are EPA 608 Universal certified, NATE certified, and BBB A+ rated, with chiller service experience since 1997. Call (734) 838-6300 or visit our contact page to book an inspection. Review our commercial HVAC service capabilities and preventive maintenance programs.