Scope of service
- Evaporator fault diagnosis and written report
- Water-side chemical cleaning and backflushing
- Tube brushing, plugging and replacement in shell-and-tube evaporators
- Brazed plate evaporator replacement
- Cross-leak (water-gas) pressure test
- Air cooler and coil cleaning, defrost parts
- Expansion valve, filter drier and oil check
- Commissioning, performance measurement and report
Evaporator fault symptoms
| Symptom | Likely cause | What is done |
|---|---|---|
| Chilled water outlet temperature rises, compressor runs for a long time | Scale or sludge on the water side, oil buildup, low refrigerant | Measure approach temperature and superheat; chemical cleaning or refrigerant check |
| Freeze alarm, low-pressure trip | Low water flow, dirty strainer, low setpoint temperature, insufficient glycol | Check flow and strainer, measure glycol, check protection settings |
| Water-side pressure drop is increasing | Plate channels or tubes are clogging | Backflushing, chemical cleaning |
| Bubbles in the expansion tank, water pressure fluctuating | Leak from the refrigerant side into the water (tube or plate crack) | Pressure test and locating the leak |
| Moisture and acid in the refrigerant circuit, filter drier saturates quickly | Water leaking into the refrigerant circuit | Leak detection, repair or replacement, system dehydration and cleaning |
| Oil return problem, low oil in the compressor | Oil buildup in the evaporator, insufficient refrigerant velocity | Check oil return, clean if necessary |
| Excessive ice on the air cooler | Defrost fault, blocked fins, fan fault | Check defrost element, sensor, drain pan heater and fan |
| Water overflowing from the drain pan, odor | Clogged drain, dirty pan | Cleaning, drain slope and disinfection |
How is an evaporator fault diagnosed?
- Data and alarm history. Operating hours, alarm records, current, pressures and temperatures are recorded.
- Thermodynamic measurement. Approach temperature, superheat and water inlet and outlet temperatures (ΔT) are measured.
- Water-side measurement. Flow and water-side pressure drop are checked; the strainer and water quality are inspected.
- Cross-leak test. The refrigerant is recovered, one side is pressurized with nitrogen and the pressure on the other side is monitored.
- Written report. Measurement values, the recommended action, and the repair and replacement costs are written as separate items.
Repair options
| Method | When | Note |
|---|---|---|
| Chemical cleaning (CIP) | Scale, sludge, fouling | The chemical is chosen according to the evaporator material; neutralization and rinsing are carried out |
| Mechanical cleaning (brushing) | Inside the tubes on flooded and shell-and-tube types | Cannot be applied to brazed plate types |
| Tube plugging | If a few tubes leak on a shell-and-tube type | Capacity drops somewhat; as the number of tubes grows, replacement becomes the better option |
| Tube replacement / retubing | Widespread tube damage on shell-and-tube types | Based on manufacturer dimensions and tube material |
| Brazing or welding repair | Leaks at connections and copper pipes | Verified by a pressure test |
| Coil washing and fin combing | Air cooler, indoor unit | Bent and blocked fins are corrected |
| Defrost and sensor parts | Cold room air cooler | Heating element, sensor, solenoid, drain pan heater |
| Insulation renewal | Sweating and heat loss | Vapor barrier continuity is important |
When is evaporator replacement needed?
| Situation | Recommendation |
|---|---|
| Frozen and cracked brazed plate evaporator | Usually replacement; a brazed joint cannot be repaired |
| Leaks in many tubes or widespread corrosion (shell-and-tube) | Replacement or retubing, depending on measurement |
| Repeated clogging, capacity not restored by cleaning | Replacement; should be considered together with water treatment |
| Refrigerant change or capacity increase | An evaporator suited to the new pressure class and capacity |
| The manufacturer's model is discontinued and parts cannot be found | Equivalent evaporator |
| The root cause of the damage has not been eliminated | The cause is fixed first; otherwise the new evaporator will be damaged too |
What is checked when choosing an equivalent evaporator
| Check | Why it matters |
|---|---|
| Capacity and water temperatures | Capacity is verified under actual operating conditions |
| Refrigerant and pressure class | Material and strength suited to the refrigerant |
| Water and refrigerant connection type and dimensions | Risk of pipe changes and extra cost |
| Number of circuits and expansion valve compatibility | Superheat control and capacity staging |
| Water-side pressure drop | The pump and flow balance should not be disturbed |
| Plate and shell material | Resistance to water quality |
| Insulation and layout | Installation and service access |
What is done after replacement
- Vacuum and nitrogen pressure test
- Oil and filter drier replacement (if needed)
- Strainer cleaning or renewal
- Expansion valve and superheat adjustment
- Glycol ratio and freeze protection check
- Flow switch and low-temperature protection test
- Performance measurement and records
- Written report
How does an evaporator replacement proceed?
- Diagnosis and report. It is verified by measurement that the fault comes from the evaporator.
- Quote. Repair and replacement options are written side by side with their cost items.
- Supply and preparation. An equivalent evaporator is supplied; shutdown and refrigerant recovery are planned.
- Removal and installation. The water side is drained, the old evaporator is removed, and the new one is connected and insulated.
- Testing and charging. Pressure test, vacuum, oil and refrigerant charging are carried out.
- Commissioning. Protection settings are tested, performance is measured and a report is provided.
So the same damage does not recur
A significant share of evaporator damage is system-related: reduced flow from a closed valve or dirty strainer, a bypassed protection, a setpoint that is too low, insufficient glycol, or uncontrolled water quality. For this reason, along with the replacement we carry out a root cause analysis and test the protection settings. For compressor-side consequences see our compressor overhaul page, and for the refrigerant side see refrigerant leaks and refrigerant charging.
Note: This page is for general technical information. For a unit-specific decision, the manufacturer's manual and on-site measurement apply. YOİ Mühendislik is an independent technical service for these brands; it does not claim to be an authorized service except for LG.
Facilities we serve
Our headquarters is in Etimesgut, Ankara. We provide this service daily in Ankara, and on a project and contract basis in all 81 provinces of Türkiye, including İstanbul, İzmir, Bursa, Antalya, Konya, Kayseri, Eskişehir, Kocaeli, Adana, Gaziantep, Samsun and Trabzon. See the areas we serve.
Frequently asked questions
Can a brazed plate evaporator be repaired?
Generally no. A brazed joint cannot be disassembled and a cracked plate cannot be repaired, so replacement is needed. Fouling, however, can be removed by chemical cleaning.
What should I do if the evaporator freezes?
Do not restart the unit and call for service. Water and refrigerant may be mixing through a cracked plate; restarting can increase compressor damage.
How can I tell if refrigerant is leaking into the water?
Bubbles in the expansion tank, fluctuating water pressure, and oil or odor in a water analysis can be signs. A definitive diagnosis is made with a pressure test.
How long does evaporator replacement take?
It depends on the unit and the evaporator's lead time; the duration is stated in writing in the quote.
Why does ice form on a cold room air cooler?
The most common causes are a defrost element or sensor fault, incorrect defrost duration, a fan fault or blocked fins.
Do you work on every brand?
As an independent technical service, we work on all brands. Parts and equivalent evaporator supply are stated in writing in the quote according to the unit.