1. Compressor does not start

Possible causes

• No power / blown fuse

• Faulty pressure switch

• Tank pressure too high

• Faulty motor or worn brushes

• Defective start capacitor

• Low voltage

• Motor protection tripped

Check

• Verify power supply

• Release pressure from tank

• Listen for click from pressure switch

• Measure voltage

• Check capacitor

Solution

• Replace capacitor

• Replace pressure switch

• Check power supply

• Motor service/repair

---

2. Compressor hums but does not start

Causes

• Faulty start capacitor

• Low mains voltage

• Extension cable too long/thin

• Motor seized

• High back pressure

Check

• Connect directly to outlet

• Test capacitor

• Empty tank pressure

Solution

• Replace capacitor

• Use correct cable

• Check motor

---

3. Compressor starts and stops quickly

Causes

• Faulty pressure switch

• Air leak

• Faulty check valve

• Overheating

• Overload

Check

• Listen for leaks

• Use soap water on fittings

• Check pressure switch

Solution

• Repair leaks

• Replace check valve

• Adjust pressure switch

---

4. Compressor runs continuously

Causes

• Air leak in system

• Air consumption too high

• Worn piston rings/valves

• Faulty pressure switch

• Clogged air filter

Check

• Check air tool consumption

• Check pressure build-up

• Listen for leaks

Solution

• Clean filter

• Fix leaks

• Pump service

• Replace valves

---

5. Compressor does not build pressure

Causes

• Air leak

• Faulty check valve

• Worn piston rings

• Valve plate failure

• Blocked intake filter

Solution

• Repair leak

• Replace valve plate

• Replace rings

• Clean filter

---

6. Safety valve releases air

Causes

• Pressure too high

• Faulty pressure switch

• Faulty safety valve

Solution

• Adjust pressure switch

• Replace valve

⚠️ Never ignore this fault.

---

7. Compressor overheating

Causes

• Poor ventilation

• Dirty cooling fins

• Long runtime

• High load

• High ambient temperature

Solution

• Ensure airflow around unit

• Clean cooling fins

• Allow cooling breaks

---

8. Water in air system

Causes

• Condensation in tank

• Tank not drained

Solution

• Drain tank regularly

• Use water separator

---

9. Compressor shuts off during operation

Causes

• Motor overload protection

• Overheating

• Voltage drop

Solution

• Let unit cool

• Check power supply

• Reduce load

---

10. Unstable operation / vibration

Causes

• Loose bolts

• Worn bearings

• Uneven surface

Solution

• Tighten bolts

• Replace bearings

• Place on stable surface

---

Typical spare parts

• Pressure switch

• Start capacitor

• Check valve

• Safety valve

• Air filter

• Motor

• Valve plate

• Piston rings

• Pressure gauge

• Hoses/fittings

---

Quick check (before service)

1. Check power supply

2. Drain tank

3. Check air filter

4. Listen for leaks

5. Check pressure build-up

6. Check temperature

This resolves approx. 60% of faults.

---

When to contact service

• Burnt motor

• No pressure build-up

• Electrical failure

• Inverter compressor fault

• Damaged pump unit

---

Quick rule of thumb

No start → power/capacitor
Humming → capacitor
Runs constantly → leak
Overheats → ventilation
No pressure → valves/piston
Safety valve blows → pressure switch