About Hitachi
Hitachi is a company of Japanese origin; its HVAC range includes VRF, chiller and heat pump products. Screw and scroll compressors are used in Hitachi chillers.
In chillers with Hitachi compressors, inverter and control board compatibility is also checked together when replacing a compressor.
Note: The corporate information is general and for information purposes only; for current and detailed information, please refer to the manufacturer's official website. The brand name belongs to the relevant company.
Compressor product groups
The table below shows the brand's compressor groups in general terms and our service approach. For model and serial information, check the nameplate.
| Type | Typical use | Service approach |
|---|---|---|
| Screw (semi-hermetic) | Medium and large chillers, refrigeration units | Bearing and gasket overhaul; replacement depending on damage |
| Scroll | Rooftop, small and medium chillers, VRF, precision air conditioning | Usually replacement |
Common faults in Hitachi compressors
| Symptom | Likely cause | Solution |
|---|---|---|
| Abnormal noise, increased vibration | Bearing wear, widening rotor clearance | Vibration and oil analysis; overhaul if needed |
| Low capacity, high discharge temperature | Internal leakage, rotor-housing clearance, capacity slide sticking | Slide and internal parts check, overhaul |
| Oil level dropping, poor oil return | Clogged oil separator, dirty oil filter, oil line problem | Separator and filter replacement, oil circuit check |
| High current, thermal overload tripping | Weak winding insulation, mechanical friction, voltage imbalance | Megger and winding resistance measurement, mechanical check |
| Does not load or unload | Solenoid or slide hydraulic circuit fault | Solenoid and slide piston service |
| Acidic oil, burnt smell | Burnt windings, moisture ingress | Compressor replacement, system cleaning, filter drier and oil change |
| Running but not cooling, rapid pressure equalization | Scroll wear or breakage | Usually compressor replacement |
| Reverse rotation, unusual noise | Phase sequence error | Correcting the phase sequence, phase protection relay |
A significant share of compressor failures stem not from the compressor itself but from the system: liquid return, oil return, low refrigerant or electrical imbalance. That is why we perform a root cause analysis along with the replacement. For details, see the pages on compressor overhaul and when a screw compressor overhaul is needed.
Our overhaul and replacement approach
- Alarm history, current, pressure and temperature records
- Oil analysis and winding (megger) measurement
- A written quote comparing overhaul and replacement costs side by side
- Renewal of bearing, gasket and valve parts
- Equivalence check for replacement: refrigerant, capacity, electrical, connections and oil
- Filter drier, oil and, if needed, system cleaning
- Commissioning and performance test
- Follow-up and report during the first hours
User manual and technical documentation
User and service manuals are copyrighted documents belonging to the manufacturers, so we do not host them on our site. We suggest the following routes:
- Note the model and serial number on the compressor nameplate
- Check the document or download section of the manufacturer's official website
- The manual of the equipment (chiller, refrigeration unit) often includes the compressor information as well
- Request it from the company or dealer you bought the equipment from
- If you cannot find it, send us a photo of the nameplate; we verify the measurements and values on site
You can find the manufacturer's current official website and documentation section by searching the model name in a search engine; we do not provide an unverified link.
What should you send us for service?
- A clear photo of the compressor and equipment nameplate
- The panel alarm screen or alarm history
- A photo of the oil sight glass or oil level
- When and how the fault started
- Information on the last maintenance and refrigerant charge
- City and access information (facility address)
Related pages
Compressor overhaul and replacement · All compressor brands · Hitachi chiller service · Spare parts · Material information
Frequently asked questions
What should I do first when a Hitachi compressor fails?
Stop the system and record the alarm history; take photos of the compressor nameplate, the panel alarms and, if there is one, the oil sight glass, and send them to us. Restarting it repeatedly can make the damage worse.
How do I get the manual for a Hitachi compressor?
Manuals are copyrighted documents belonging to the manufacturer; we do not host them on our site. You can get one from the manufacturer's official website or from the equipment dealer, using the model and serial number. If you want us to assist, we compare the values in the manual with on-site measurements.
Overhaul or replacement for a Hitachi compressor?
The decision is made based on current, megger, oil analysis and mechanical inspection. Overhaul comes to the fore for mechanical wear; replacement for burnt windings or severe internal damage.
Is YOİ Mühendislik an authorized service for Hitachi?
No. YOİ Mühendislik works as an independent technical service for this brand and does not claim to be an authorized service. The brand name is used only to indicate which compressors we work on.