AC Guide · How it works
What is the difference between an inverter and a non-inverter AC?
By the Citi Cool engineering team. Updated 2026-10-17. Sources: Daikin India, each AC's Daikin spec page, the Bureau of Energy Efficiency and our own service team.
The short answer
- The one real difference: How the compressor is run. A non-inverter has one speed: full power or off. An inverter speeds its compressor up or slows it down by changing the frequency of the power it sends it.1
- What "inverter" means: A frequency changer. It is a board inside the AC, not a battery backup. In Daikin's words, "an inverter is a device for converting frequency".2
- What you notice: Steadier, and quieter. A non-inverter comes back on at full blast each time the room warms a degree or two. An inverter holds the setting with smaller swings, and its quietest indoor setting is 32 dBA to the GTQ50's 38.46910
- On your bill: It depends on your room. An inverter uses fewer units only when the AC has power to spare. Flat out on a top floor in peak heat, both draw full power, and the GTKL50 3 Star is rated at 7.17 A to the GTQ50's 5.8 A.15910
Watch both compressors cool the same room
The live explainer on this page puts two 1.5 ton ACs, both set to 24°C, in the same hot room and plays two hours in about 24 seconds, at 35°C, 40°C or 45°C outside.1
- Both start at full power. A hot room needs everything, so both compressors run flat out. Daikin's example of a 1.5 ton inverter runs anywhere from 0.3 to 1.7 ton, so it can briefly run above its size.1
- At 24°C the non-inverter switches off. It has two settings, full power or off.5
- The room warms, so it restarts with a jolt. Its power drops when it stops and goes up sharply at each restart.1
- The inverter slows down instead. It turns its compressor down to what the room needs and holds 24°C without switching off.2
- What it means for you. Steadier comfort and far fewer starts. Fewer units in hours like these, when the AC has power to spare; when it can't keep up, both run flat out.15
What "inverter" actually means
Both ACs take the same supply from your wall: single phase, 230 V, 50 Hz.910
A non-inverter's compressor has one fixed speed, so it can only run or stop. An inverter AC changes the frequency of the power going to its compressor, and with it the compressor's speed.1
A 12 × 12 ft bedroom in Delhi with a west window, set to 24°C, at four moments, worked out by our room model. The live explainer shows the power going to each compressor and how fast it turns.1516
| Moment | Outside | The room needs | GTQ50 (Non-inverter) | GTKL50 (3 Star inverter) |
|---|---|---|---|---|
| 3 am, a cool night | 27.8°C | 0.30 ton | Full speed for 21% of the time, off for the rest. 0.28 units that hour. | At its lowest, 0.4 ton, it still gives more than the room needs, so it switches off and on too. 0.24 units that hour. |
| 10 pm, a warm evening | 34.3°C | 0.54 ton | Full speed for 37% of the time, off for the rest. 0.50 units that hour. | Runs all the time, turned down to about 38% of its cooling. 0.43 units that hour. |
| 4 pm, a hot afternoon | 40.5°C | 0.94 ton | Full speed for 65% of the time, off for the rest. 0.87 units that hour. | Runs all the time, turned down to about 66% of its cooling. 0.79 units that hour. |
| 4 pm, top floor, the hottest day | 45.1°C | 1.35 ton | Full speed all the time, and still not enough. The room drifts up to 25.2°C. 1.33 units that hour. | Full speed all the time, with nothing left to turn down. The room drifts up to 25.4°C. 1.65 units that hour. |
- The wall gives both the same power. Single phase, 230 V, 50 Hz, the supply on both ACs' Daikin spec pages.
- The non-inverter takes it or leaves it. Its compressor has one speed. To cool less, it can only switch off and wait.
- The inverter board changes the frequency. A lower frequency turns the compressor slower: less cooling, less current. A higher one, faster.
Daikin puts it simply: "An inverter is a device for converting frequency." Its inverter ACs vary their cooling by adjusting the frequency of the power to their compressors. A slower compressor moves less refrigerant and draws less current.21
A non-inverter can only start or stop its compressor to hold the room. When it stops, its power drops right down. When it restarts, Daikin says, the current "goes up sharply".1
An inverter can only turn down so far. Daikin rates the GTKL50's lowest cooling at 1.4 kW, about 0.4 ton. At 3 am our room model has this bedroom needing 0.30 ton, less than that, so the inverter also switches off and on, at its lowest speed.1015
What's different inside
From outside the two look alike: Daikin's GTQ50 and GTKL50 outdoor units are both 595 × 845 × 300 mm. What differs is the compressor and the electronics that drive it.910
Non-inverter (GTQ50)
- Compressor: one speed. Runs at full power until the room reaches the setting, then stops. When the room warms, it kicks in again at full power.5
- Capacitor and simple controls. On or off, nothing in between. Daikin says its parts are standard and straightforward to repair. The usual repair our team sees is a capacitor, about ₹1,500.517
- Power in. The GTQ50 runs on 160 to 264 V.9
Inverter (GTKL50)
- Swing compressor: variable speed. Its speed rises and falls with the room. Daikin's patented swing compressor turns smoothly, with less friction and vibration, and keeps refrigerant from leaking during compression. Daikin's inverter compressors use a reluctance DC motor, which Daikin says gets more power from less current and works best at the low speeds an AC runs at most.110
- Inverter board (PCB). Changes the frequency of the power sent to the compressor, and so its speed. Daikin covers it for 5 years and calls it one of an AC's most expensive parts. After the warranty, a repair costs about ₹3,500; a new board costs much more.18717
- Power in, stabiliser inside. The GTKL50 runs on 130 to 285 V, with the stabiliser built in.10
What you notice in the room
Room temperature
Non-inverter: Cools at full power, switches off at the setting, and comes back on at full blast once the room warms a degree or two.4
Inverter: Slows down as it nears the setting and holds it with minimal fluctuations.62
Sound
Non-inverter: Quietest indoor setting: 38 dBA for the GTQ50.9
Inverter: Quietest indoor setting: 32 dBA for the GTKL50, 31 dBA for the FTKU50. Daikin also says its inverters run quieter.10114
Daikin's lab figures. A real room is a little louder.
Starting up
Non-inverter: Starts at full power every time it switches on, and runs that way until the room is cool.5
Inverter: Starts at maximum capacity to cool the room fast, then slows down. The GTKL50 can run up to 5.3 kW, above its rated 5 kW.210
Hot days
Non-inverter: Full cooling up to 43°C outside. The GTQ50 works from 19.4 to 50°C.9
Inverter: Full cooling up to 43°C for the GTKL50 and 46°C for the FTKU50. The GTKL50 works from 16 to 52°C.1011
In Delhi heat the series matters as much as the type.
What happens to the electricity
A non-inverter draws its full power whenever its compressor runs, and almost nothing when it stops. In Daikin's words, "the power drawn is always at max when the compressor is running".4
An inverter that is turned down draws less: a slower compressor moves less refrigerant, for less current.1
Flat out, that advantage is gone. Daikin rates the GTKL50 3 Star at 7.17 A at full power and the GTQ50 non-inverter at 5.8 A; the FTKU50 5 Star at 5.51 A. So in a room a 1.5 ton can't keep up with, the 3 Star can use more than the non-inverter.9101115
Two Delhi rooms, 12 × 12 ft, set to 24°C, from our room model:15
| Air conditioner | Middle-floor bedroom, at night (10 pm–6 am) | Top-floor room, afternoons, hottest day (12–6 pm) |
|---|---|---|
| GTQ50 (Non-inverter) | 2.8 units, keeps up every hour | 7.4 units, flat out 2 of 6 hours |
| GTKL50 (3 Star inverter) | 2.4 units, keeps up every hour | 8.4 units, flat out 3 of 6 hours |
| FTKU50 (5 Star inverter) | 1.8 units, keeps up every hour | 5.9 units, keeps up every hour |
On their BEE labels, over a 1,600-hour year: the GTQ50 1,002 units, the GTKL50 880 units, the FTKU50 679 units.12
Set up your own room, floor and city in the inverter vs non-inverter buying guide, or see units by the hour in how many units a 1.5 ton AC uses.
How BEE rates each kind
Every AC sold in India carries a BEE star label. Behind the stars is the ISEER: the cooling an AC gives over a year divided by the electricity it uses in that year. Higher is better.13
BEE works it out over a 1,600-hour cooling year at outside temperatures from 24°C to 43°C, from weather data for 54 Indian cities. It tests a fixed-speed AC at full capacity, and an inverter at full and at half capacity.1314
Today's 1.5 ton picks: the GTQ50 at ISEER 3.9 (2 Star), the GTKL50 at ISEER 4.4 (3 Star), the FTKU50 at ISEER 5.7 (5 Star).12
Star bands change from time to time, and each label says how long it is valid. To compare ACs from different years, compare the ISEER.14
Side by side
| Non-inverter | Inverter | |
|---|---|---|
| Compressor speed | One: full power or off | Varies with the room1 |
| How it holds the setting | Switches off, then restarts at full power | Slows down and keeps running52 |
| What changes the speed | Nothing: it has one speed | The inverter board (PCB), by changing the frequency117 |
| Cooling, 1.5 ton | 5.05 kW, fixed | GTKL50: 1.4 to 5.3 kW · FTKU50: 1.58 to 5.9 kW91011 |
| Power supply | Single phase, 230 V, 50 Hz | Single phase, 230 V, 50 Hz91011 |
| Current at full power | 5.8 A | GTKL50: 7.17 A · FTKU50: 5.51 A91011 |
| Runs on | 160 to 264 V | GTKL50: 130 to 285 V, stabiliser inside · FTKU50: 130 to 285 V, stabiliser inside91011 |
| Works in outside temperatures | 19.4 to 50°C | GTKL50: 16 to 52°C · FTKU50: 10 to 55°C91011 |
| Full cooling up to | 43°C | GTKL50: 43°C · FTKU50: 46°C91011 |
| Quietest indoor setting | 38 dBA | GTKL50: 32 dBA · FTKU50: 31 dBA91011 |
| Daikin swing compressor | No | GTKL50: Yes · FTKU50: Yes91011 |
| BEE tests it at | Full capacity | Full and half capacity14 |
| Units a year, BEE label | 1,002 | GTKL50: 880 · FTKU50: 67912 |
| Daikin warranty | 1 year on the AC, 5 years on the compressor | 1 year on the AC, 5 years on the PCB, 10 years on the compressor8 |
| Repairs after warranty | Rare. A capacitor costs about ₹1,500 | PCB repair about ₹3,500; a new PCB much more17 |
| Price today | ₹36,100 (GTQ50, 24-hour delivery) | ₹38,000 (GTKL50, ordered in, 5 to 7 days) · ₹46,400 (FTKU50, 24-hour delivery)18 |
Which lasts longer, and what repairs cost
Daikin says an inverter's compressor wears less, because it does not keep switching on and off.3
Our service team sees it from the other side. Non-inverters are very sturdy and rarely break down, and the usual repair, a capacitor, costs about ₹1,500. An inverter's PCB costs about ₹3,500 to repair after the warranty, and a new one much more.17
Daikin's warranty follows the parts. A non-inverter split gets 1 year on the AC and 5 years on the compressor. An inverter split gets 1 year on the AC, 5 years on the PCB and 10 years on the compressor. The PCB cover does not include handling and fixing charges.8
From our service team. Cooling Delhi since 1990. Authorized Daikin dealer since 2003.
- Our own team installs and services every AC we sell, so we see both kinds years after they go in.
- Sales and service under one roof: the team that sells you the AC is the team you call when it needs a repair.
Service & repairs: 95990 83770
Things people get wrong
Myth: An inverter AC runs on my home inverter.
Fact: The word has nothing to do with power backup. The inverter is the board inside the AC that changes the frequency of the power going to the compressor, and so its speed.21
Myth: An inverter AC never switches off.
Fact: It turns down only so far: the GTKL50's lowest is 1.4 kW, about 0.4 ton. A cool night can need less, 0.30 ton at 3 am in our middle-floor bedroom, and then it switches off and on at its lowest.1015
Myth: An inverter always uses less electricity.
Fact: Only when it has power to spare. Flat out it draws its full power, and the GTKL50 3 Star is rated at 7.17 A against the GTQ50's 5.8 A.91015
Myth: A non-inverter is old and unreliable.
Fact: Daikin still makes them, with standard parts that are straightforward to repair. Our service team finds them very sturdy, with few breakdowns.517
Myth: Inverter ACs cool slowly.
Fact: Daikin's inverters run at maximum capacity as soon as they start, then slow down once the room is cool.2
Questions people ask
What is the difference between an inverter and a non-inverter AC?
How the compressor is controlled. A non-inverter's compressor has one speed: it runs at full power until the room reaches the setting, stops, and restarts at full power when the room warms. An inverter changes the frequency of the power to its compressor, so it can speed up or slow down to match the room and keep running.15
What does "inverter" mean in an AC?
A device that converts frequency. In an inverter AC it changes the frequency of the power the compressor gets, which sets the compressor's speed. It has nothing to do with a home inverter or battery backup.21
Does an inverter AC switch off when the room is cool?
Usually it slows down instead. It can only go down to its lowest speed: 1.4 kW, about 0.4 ton, for the GTKL50. If the room needs less, as at 3 am in a middle-floor Delhi bedroom (0.30 ton in our room model), it switches off and on at that lowest speed.10215
Which is quieter, an inverter or a non-inverter AC?
Daikin says its inverters are quieter. Its lab figures for the quietest indoor setting: 38 dBA for the GTQ50 non-inverter and 32 dBA for the GTKL50 3 Star, 31 dBA for the FTKU50 5 Star. A real room is a little louder than a lab.491011
Do inverter and non-inverter ACs need a stabiliser?
Daikin builds the stabiliser into the GTKL50: it runs on 130 to 285 V. The GTQ50 non-inverter runs on 160 to 264 V. If the voltage swings more than an AC can take, Daikin says it stops to protect itself and starts again on its own about 3 minutes after the supply is back to normal.1096
Do inverter and non-inverter ACs look different?
Hardly. The GTQ50 and GTKL50 outdoor units are both 595 × 845 × 300 mm, and the indoor units 298 × 885 × 229 mm and 298 × 885 × 239 mm. The difference is the compressor and the board inside the outdoor unit.910
Which lasts longer?
Daikin says an inverter's compressor wears less because it doesn't keep switching on and off. Our service team finds non-inverters very sturdy, and their usual repair, a capacitor, costs about ₹1,500, against about ₹3,500 for an inverter PCB repair after the warranty. Daikin covers an inverter's compressor for 10 years and a non-inverter's for 5.3178
What is a swing compressor?
Daikin's patented compressor for its inverter ACs. Daikin says its smooth rotation cuts friction and vibration and stops refrigerant gas leaking during compression. The GTKL50 and the FTKU50 have one; the GTQ50 non-inverter does not.110119
Does an inverter AC use less electricity?
On the BEE labels, yes: the GTQ50 1,002 units, the GTKL50 880 units, the FTKU50 679 units over a 1,600-hour year. In your room, it depends on whether the AC has power to spare. In a middle-floor Delhi bedroom at night, our room model has the inverters using 14 to 34% less. In a top-floor room on the hottest afternoon, the GTKL50 uses 8.4 units to the GTQ50's 7.4, because both run flat out.1215
Sources
- Inverter Technology: how inverter and non-inverter ACs control the compressor, the swing compressor and the DC motor (Daikin India)
- Daikin Inverter Technology: "An inverter is a device for converting frequency" (Daikin India)
- How Inverter AC Technology Works (Daikin India)
- Inverter Technology Demystified: How Variable Speed Compressors Save You Money (Daikin India)
- Choosing the Right Cooling Solution: Comparing Inverter and Non-Inverter 1.5 Ton Split ACs (Daikin India)
- FAQs: what an inverter AC is, and what happens when the voltage swings (Daikin India)
- Top 10 Reasons to Buy Daikin 5 Star Inverter AC (Daikin India)
- Product Warranty (Daikin India)
- The GTQ50's spec page: power supply, voltage range, cooling range, operating current, outside temperatures, sound level and compressor (Daikin India)
- The GTKL50's spec page: power supply, voltage range, cooling range, operating current, outside temperatures, sound level and compressor (Daikin India)
- The FTKU50's spec page: power supply, voltage range, cooling range, operating current, outside temperatures, sound level and compressor (Daikin India)
- BEE star label figures from the Daikin RA Master Catalogue 2026, shown on each product page (Daikin)
- Indian Seasonal Energy Efficiency Ratio (Vikaspedia, Government of India)
- Star labelling schedule: the ISEER method, test points and label validity (Bureau of Energy Efficiency)
- Our room model: Daikin's heat-load method for a room, hour by hour, as in our AC calculator (Citi Cool engineering)
- Climate normals for Palam, New Delhi, as used in our AC calculator (India Meteorological Department)
- Repair costs and breakdowns seen by our own service team, October 2026 (Citi Cool)
- Daikin 1.5 ton AC prices and stock today (citicool.in)
More AC questions, answered
- Which ton AC does my room need?: Sized for your city's hottest day, with the right AC from stock.
- Inverter vs non-inverter AC: which one should you buy?: Check whether an inverter saves anything in your own room, work out your 5-year cost, and check cooling in Delhi heat.
- How many units does a 1.5 ton AC use?: Your room hour by hour, the label averages by size, and what an AC adds to a Delhi bill.
- Coming next: 3 Star or 5 Star: is 5 Star worth it?
- Coming next: What temperature should I set my AC to?
- Coming next: VRV or split ACs for a whole home?
- Coming next: How often should an AC be serviced?
Still not sure which one fits your room? Call sales on 77039 00307, or book a ₹99 video call with an engineer, adjusted against your order.