The faults we are called for most
| What you see | What it usually is | On site or workshop? |
|---|---|---|
| Runs but will not reach pressure | Inlet valve not opening, separator blocked, leaking minimum-pressure valve, worn airend, belt slip | Usually on site |
| High temperature trip | Dirty oil cooler, thermostatic valve stuck, low oil level, wrong oil, blocked ventilation, fan failure | On site |
| Oil in the air line | Separator element passing, scavenge line blocked, oil level too high, wrong oil | On site |
| Motor trips or will not start | Overload setting, contactor, star-delta timing, supply voltage, bearing drag | On site |
| Water in the air | Aftercooler or drain not working, dryer fault, undersized dryer for the ambient | On site |
| Noise, vibration, metal in oil | Airend bearings, coupling, piston rings or valves | Workshop, with a hire machine meanwhile |
| Portable diesel: starts cold, loses power hot; black or white smoke | Fuel system, injectors, air filter, turbo, cooling | On site for most; engine work in the workshop |
| Piston compressor pumping slowly | Valve plates, rings, head gasket, intake filter | On site |
What a repair visit looks like
A service engineer arrives with the tools and the common parts for the make and model you have told us about. The first hour goes on finding the cause, not just the symptom: pressures and temperatures are read at the right points, the control is checked, and the machine is run under load. You are told what was found, what it needs, and what it will cost before parts are fitted. After the repair the machine is run and the readings are recorded, so the next visit starts from a known state. The on-site compressor service and repair page explains what can and cannot be done in the field.
When the machine cannot be fixed on site
Airend overhauls, engine rebuilds, machining, balancing and clean assembly are workshop jobs. Two things keep your plant running while that happens: a hire machine from our own fleet, tied in on the day, and a workshop that does this work every week. The compressor overhauling and refurbishment page sets out what an overhaul includes and when it is worth doing rather than replacing the machine.
Parts for the repair
Parts come from the nameplate, not from a guess. For the common makes we hold filters, separators, valves, sensors, belts and coolers, and we source the rest against the serial number. Genuine or compatible is your choice; we explain the difference for each part. The spare parts section and find my part show how we identify what you need.
Preventing the next breakdown
Most repair calls come from machines that missed a service. If a compressor matters to production, an annual maintenance contract – planned visits, parts on the day, breakdown support on agreed terms – costs less than one emergency. The compressor AMC page explains the options.
Where we come to you
Hyderabad and Secunderabad in all directions, the industrial belts around the city, the rest of Telangana and Andhra Pradesh, and districts within about 300 km of Hyderabad. For machines further away we advise on the phone first and travel for work that justifies it.
Before you call: Three things that are safe to check yourself
Some breakdowns are not breakdowns. Before a visit, with the machine isolated and the pressure released, an operator can safely look at three things: the air filter (a choked filter starves the machine and raises the discharge temperature); the oil level in the sight glass with the machine stopped and settled; and the cooler face, which in a dusty plant can pack solid within weeks. If any of these is the cause, the fix is routine and the visit becomes a service rather than a repair. Anything that involves opening the pressure system, the electrical panel or the engine is for the service engineer; the safety, isolation and permit-to-work guide explains why.
How a fault is traced, not just cleared
A compressor that trips on high temperature can be made to run again by cleaning the cooler. If the real cause is a thermostatic valve stuck on bypass, it will trip again on the next hot afternoon, and the second call-out costs more than a proper diagnosis would have. Our repair method follows the air and the oil through the machine in order:
- Read before touching: controller history and fault codes, hour reading, the last service date, and what the operator saw.
- Measure at the right points: inlet vacuum, interstage and discharge pressures, oil injection temperature, discharge temperature, separator differential, motor current per phase, voltage under load. The machine’s own gauges are checked against a reference before they are trusted.
- Run under load: many faults only appear at full load and temperature; a machine that behaves at idle has told you nothing.
- Isolate the cause: a pressure that falls with the machine stopped is a leak or a valve; a temperature that climbs with a clean cooler is oil, thermostat or airend; oil at the tool with a correct level is a separator or scavenge problem.
- Quote before fitting: what was found, the part and labour needed, and whether it can be done now, before any part is fitted.
- Prove the repair: run under load, record the readings, and leave the sheet with the machine.
The breakdown diagnostics and fault triage guide sets out this method in full, with the readings that point to each cause.
Repairs by machine type
| Machine | Typical on-site repairs | Workshop work |
|---|---|---|
| Oil-injected rotary screw | Inlet and minimum-pressure valve kits, separator element, thermostatic valve, cooler cleaning, sensors, solenoids, belts, contactors, shaft seal on some models | Airend bearing overhaul or exchange; motor rewind; gearbox |
| Oil-free screw and tooth | Filters, sensors, cooler cleaning, drains, control faults | Element overhaul or exchange; gearbox |
| Reciprocating (piston) | Valve plates, head gaskets, rings, intake filter, unloader, pressure switch, belts | Cylinder rebore, crankshaft, full rebuild |
| Portable diesel screw | Engine service items, injectors, fuel system, cooling, belts, unloader and regulator, separator, hoses, lights and towing gear | Engine rebuild; airend overhaul; canopy and chassis repair |
| Dryers and filters | Drains, fan, pressure switches, refrigerant leaks and gas charge, desiccant change, element change | Compressor or heat exchanger replacement |
The faults Hyderabad’s climate causes
Three conditions do most of the damage to compressors in Telangana and Andhra Pradesh. Heat: at 40–45 °C ambient an air-cooled machine has little margin, and a cooler that is 30% blocked, a thermostatic valve that opens late or an oil that has aged all show up as afternoon trips between April and June. Dust: quarries, batching plants, textile units and open sites fill cooler cores and air filters faster than the service interval allows, and dust past a damaged filter scores the airend. Monsoon humidity: a dryer sized for a European ambient cannot hold the dew point in August, condensate drains fail, and water reaches tools and product. The repair for each is straightforward; the prevention – shorter cleaning intervals, a correctly sized dryer, a thermostat checked before summer – is cheaper still, and is what an AMC is for.
What a repair costs, and what we will not do
The call-out and diagnosis are quoted up front. Parts and labour are quoted after the fault is found, before anything is fitted, with the part numbers stated. We will not fit a part to see if it helps, bridge a sensor to keep a machine running past a real fault, or recommend an overhaul where the numbers say replace. When a repair is not worth doing, the service engineer will say so and show you the alternatives – a used, refurbished or new machine, or hire – with the costs side by side, because we sell and hire as well as repair and have no reason to steer you to one answer. The overhaul versus replacement decision tool shows the comparison.
A worked example
A printing unit in Nacharam calls at 2 pm: its 30 hp screw compressor has tripped twice on high temperature and the presses are stopping. On the phone the engineer asks for the controller reading, the hour meter and when the oil was last changed: 11,000 hours, oil changed 3,000 hours ago, a dark sight glass. On site the cooler is half blocked with paper dust, but after cleaning the discharge temperature still climbs above the band at full load, and the oil smells burnt. The cause is aged oil and a thermostatic element that is opening late; the cooler was a contributor, not the cause. The repair is an oil and filter change, a new thermostatic element and a full cooler clean, proved by a 30-minute run at load with the temperature steady. The engineer also notes that the separator differential is close to its limit and schedules its change at the 12,000-hour service, so the next stoppage is planned rather than sudden.
Keeping production running while a machine is in the workshop
When an airend or an engine has to come out, the plant does not have to stop. A hire machine from our fleet, delivered with hoses and a tie-in valve, takes the load for the days or weeks the workshop needs; for plants with a single compressor this is the difference between a repair and a shutdown. The compressor breakdown air page explains how the changeover is done.
How Reddy Compressors helps
Independent multi-brand specialist since 2002; more than 20 service engineers and technicians; own workshop and rental fleet, so a repair never leaves you without air; spares for the common makes on the shelf.
What to send us
- A photo of the nameplate, and what the machine is doing (or not doing)
- Any fault code or lamp on the controller, and your location
- For a portable diesel unit, the hour reading and when it was last serviced
- WhatsApp 99590 60718; open 7 days, 8:30 am to 8:30 pm
Frequently asked questions
Do you repair all makes?
Yes. Rotary screw, piston, portable diesel and oil-free compressors of every major make, and the dryers and filters with them. We are an independent specialist, not tied to one manufacturer.
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Can you come today?
Tell us the fault and the location and the engineer will tell you honestly when he can be there. Breakdowns of production machines are given priority.
Do you repair the motor or the engine too?
Motor faults are diagnosed on site and rewinding is arranged where needed; engine repairs on portable units are done by our technicians, with major rebuilds in the workshop.
What does a repair cost?
The visit and diagnosis are quoted up front; parts and labour are quoted after the fault is found and before they are fitted.
Can you give me a machine while mine is repaired?
Yes, from our own rental fleet, delivered with hoses to tie in.
My compressor is from a make you may not have seen. Can you still repair it?
Almost always. Screw and piston compressors share the same principles whatever the badge; we identify parts from the serial number and source them, and we are honest when a part is unavailable.
Do you repair air dryers and filters as well?
Yes. Refrigerant dryers, desiccant dryers, line filters and drains are part of the same visit.
Can you tell me the fault over the phone?
Often we can narrow it down from the symptoms, the fault code and the readings, which lets the engineer bring the likely parts; the diagnosis is confirmed on site.
Is it worth repairing an old compressor?
Depends on the airend or engine condition and the energy cost. We show the repair cost against replacement so you can decide; sometimes the honest answer is to replace.
Related pages
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer, Reddy Compressors. Last updated 4 November 2026. How our engineering content is reviewed.