You switch on the fan. Nothing. Or worse, the blades move so slowly you can count each turn. Most people panic here and either call a technician or start shopping for a new fan. Both are expensive. Half the time, the fix takes ten minutes and costs nothing.

Short answer: Check these seven things in order: power supply, switch, capacitor, blade jam, grease buildup, bearing wear, and duct blockage. Most slow or dead fans fail on the first three. A weak capacitor is the number one cause of a fan that hums but won't spin.

Last updated: September 2026. Repair costs and part availability can change. Check with a licensed electrician before opening any wiring.

What's in this post

• Safety first, read this line
• The 7 faults, in order
• Quick diagnosis table
• When to repair and when to replace
• What Indian homes face most
• Common questions

Safety First

Before you touch anything, switch off the power at the main board. Not just the wall switch. The main board. If you are not comfortable opening a switch box, stop and call a licensed electrician. Electrical work is not a DIY job, and no blog post changes that.

The 7 Faults to Check

1. No power reaching the fan

Start at the wall switch. Flip it a few times. Sometimes the switch itself is dead, not the fan. Test the same socket with another appliance. If that works, power is fine and the problem is inside the fan or its wiring. If nothing works, the fault is in your board or wiring, and that needs an electrician.

2. A burnt or loose switch

Switches wear out. A loose connection inside the switch box causes the fan to run slow or stop randomly. If the fan works sometimes and not other times, this is your likely culprit. Tighten the connections or replace the switch. Again, with power off.

3. Weak capacitor

This is the most common reason a fan hums but does not spin. The capacitor gives the motor its starting push. When it weakens, the motor struggles. Symptoms: humming sound, blades barely moving, or the fan starts only if you nudge the blades by hand. A replacement capacitor usually costs somewhere between Rs 100 and Rs 300 [VERIFY local pricing]. If you hear a hum and see no spin, check this first.

4. Blade jam or obstruction

Switch off power. Try turning the blades by hand. They should move freely. If they feel stuck or scrape against something, look for a bent blade, a loose screw, or a foreign object. Insect nests are common in fans that sit unused for months. Clear the obstruction and test again.

5. Grease and dust buildup

Indian kitchens produce heavy grease. That grease catches dust and forms a thick film on the blades and the motor shaft. A greasy blade becomes heavy and unbalanced, so the fan spins slow and wobbles. Clean the blades and the shutter every 4 to 6 weeks if you fry daily. Warm water with a little dish soap works. Dry fully before refitting.

6. Worn bearings

Listen carefully. A grinding or rumbling sound that gets worse over time usually means worn bearings. The shaft no longer spins smoothly, so the motor works harder and the fan slows down. Bearings can be replaced, but on budget fans the repair cost often comes close to a new fan. Ask the technician for a quote first.

7. Blocked or crushed duct

If your fan is a ducted model, check the duct. Birds nest inside. Bends get crushed. Dust builds up on the inner walls. All of this blocks airflow. The fan may spin fine but feel useless because the air has nowhere to go. Disconnect the duct and test the fan in free air. If it spins fast, the duct is your problem.

Quick Diagnosis Table

Save this table. It saves a service call.

When to Repair and When to Replace

Repair makes sense if the fan is under 3 to 4 years old and the fault is a capacitor, a switch, or dirt. These are cheap fixes.

Replace makes sense if:

• The motor winding has burnt out. You will usually smell a burnt plastic odour.
• The fan is over 6 to 7 years old and this is the second or third fault.
• The body has rusted through, which happens faster in humid coastal areas.
• Repair quotes cross about half the price of a new fan. At that point, a new fan with a warranty is the smarter buy.

Rule of thumb: if the repair costs more than 40 to 50 percent of a new fan, replace it.

What Indian Homes Face Most

Three problems come up again and again across India.

First, grease. Indian cooking produces more oil vapour than most cooking styles. That vapour settles on the blades and motor shaft. In dusty regions, it turns into a sticky paste that slows the fan within months. Cleaning is not optional here. It is maintenance.

Second, voltage fluctuation. In many areas, voltage drops during peak hours. A fan running on low voltage overheats and the winding weakens over time. If your lights dim when the fan starts, that is a warning sign. A voltage stabiliser for the fan can help in areas with frequent fluctuation.

Third, long idle periods. Fans in guest rooms or second bathrooms sit unused for months. Dust settles, grease hardens, and insects move in. Run every fan in the house for ten minutes once a month. It takes ten minutes and prevents most of these faults.

If you want the bigger picture on home airflow and ventilation, read our home ventilation systems guide for India.

When a New Fan Makes More Sense

If your fan is old, noisy, and rusted, and this is the third breakdown, stop repairing it. A new fan with a warranty will cost less over the next two years than repeated repairs.

For kitchens between 8 x 8 and 10 x 8 feet, the Wadbros Tornado exhaust fan is a solid middle range pick. It suits closed kitchens with a nearby external wall. It does not suit open layouts or very long duct runs, where you need higher static pressure instead. You can see the range on the MR Homes exhaust fan collection.

If power bills and noise matter to you, look at BLDC models like the Wadbros Storm BLDC. BLDC stands for brushless direct current. These motors use less electricity and run quieter than standard motors.

Not sure whether to fit it yourself? Read our guide on DIY vs professional exhaust fan installation. Wiring always goes to a licensed electrician.

Common Questions

Why is my exhaust fan humming but not spinning?

A weak capacitor is the most likely cause. The motor gets power but not enough starting torque. Replace the capacitor. It is usually a cheap part. If the hum continues after replacement, the motor winding may be damaged and the fan needs replacing.

Can I fix a slow exhaust fan myself?

For cleaning, blade checks and obstruction removal, yes, with the power off. For capacitor replacement, switch repair or any wiring, call a licensed electrician. Do not open the motor housing yourself.

How much does exhaust fan repair cost in India?

A capacitor replacement is usually the cheapest fix, often under Rs 500 including labour [VERIFY local rates]. Bearing replacement costs more. If the motor winding has burnt, repair is rarely worth it.

Why does my exhaust fan spin slowly only sometimes?

Intermittent slow spinning usually points to a loose switch connection or fluctuating voltage. Check the switch first. If your lights also dim when appliances start, get the voltage checked.

Should I replace an exhaust fan that is 8 years old?

If it has had two or more repairs, yes. Old motors lose efficiency, draw more power, and run louder. A new fan with a warranty is usually the better long term call.

Your Next Step

Switch off the main power. Run through the seven checks in order. Most faults show up in the first three. If it is a capacitor or a cleaning issue, you have your answer today. If the motor is burnt or the fan is very old, compare repair cost against a new fan before deciding. The MR Homes team is available 24/7 if you want help choosing a replacement.