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How Many Amps Does a 3 Ton Air Conditioner Use? (Answered)

Written by Edwin Jones / Fact checked by Andrew Wright

how many amps does a 3 ton air conditioner use

Central air conditioners are vital equipment to maintain a comfortable ambient temperature in large spaces or entire homes. The most common variant found at homes is the 3-ton air conditioner.

To properly install this high-powered equipment, we need to know how many amps does a 3 ton air conditioner use. We estimate that the current draw will be around 12 amps based on a SEER2 of 13.4.

Understanding Power Efficiency of 3-ton Air Conditioners


A 3-ton central air conditioner is given an efficiency rating based on its ability to remove energy from the room using its electrical input. An air conditioner with a higher rating means it can remove more energy.

Air conditioners are traditionally rated with an energy efficiency rating or EER. It is a ratio between the amount of heat it can remove for a given power consumption from 80⁰F to 95⁰F at 50% humidity. It is expressed as:

\[ \text{Efficiency rating} = \frac{\text{Capacity in BTU/hr}}{\text{Input power in watts}} \]

While EER is a standard way of expressing energy efficiency, it does not reflect seasonal temperature changes during summer. A more practical rating is the seasonal energy efficiency ratio or SEER. SEER is measured from 65⁰F up to 104⁰F.

A more robust rating to simulate real-world conditions is SEER2. SEER2 is introduced in 2023 and will supersede SEER in the future. What’s different about SEER2 is the higher static pressure than SEER which is claimed to represent real-world applications better than the older rating.

SEER and SEER2 are also ratios, just like EER. The testing conditions for SEER and SEER2, though, are broader than EER. Thus, SEER and SEER2 are more commonly used in central air conditioners.

Calculating the Estimated Amp Draw for 3 Ton Air Conditioner


We may estimate the current draw of a 3-ton AC unit using the SEER2. We can re-arrange the previous equation to get the power and extract current:

\[ \text{SEER2} = \frac{\text{Capacity in BTU/hr}}{\text{Input power in watts}} \]

\[ \text{SEER2} = \frac{\text{Capacity in BTU/hr}}{\text{voltage in volts} \times \text{current in amps}} \]

\[ \text{Current in amps} = \frac{\text{Capacity in BTU/hr}}{\text{voltage in volts} \times \text{SEER2}} \]

The minimum SEER2 rating for a 3-ton air conditioner in a lot of US states in the North is 13.4. If 3 tons is equivalent to 36,000 BTU/hr and runs mostly on 220 volts, then the estimated AC amps will be:

\[ \text{Current in amps} = \frac{\text{Capacity in BTU/hr}}{\text{voltage in volts} \times \text{SEER2}} = \frac{36,000 \text{ BTU/hr}}{220 \text{ volts} \times 13.4} = 12.21 \text{ amps} \]

Here is a simple amperage chart based on the minimum SEER2 ratings required by some parts of the US:

US location Minimum SEER2 Rating for 3 ton AC units Amps for air conditioner based on SEER2
North 13.4 12.21 amps
Southeast and Southwest 14.3 11.44 amps

Here is an amperage chart of some central air conditioner brands. Most of the published data show ranges of SEER2 values and BTU/hr, so identifying the expected amp draw from a 3-ton air conditioner is not readily available. We made a range instead.

Brand Series Tonnage BTU/hr Minimum SEER2 Rating Estimated current of minimum BTU based on SEER2 (amps) Estimated current of max BTU based on SEER2 (amps)
Lennox SL28XCV SERIES 1.7 to 4.6 20800 to 55000 20.2 4.68 12.38
Amana ASXV9 1.8 to 4.3 21600 to 52000 19 5.17 12.44
Daikin DX9VC 1.8 to 4.3 21600 to 52000 19 5.17 12.44
GE NS23A Series 2.9 to 4.9 35000 to 58500 18.6 8.55 14.30
Royalton 4AC17L 1.4 to 3.8 17300 to 46000 15.2 5.17 13.76
Carrier COMFORT 15 SEER2 AC 1.5 to 4 17600 to 48500 15.2 5.26 14.50
Arcoaire PERFORMANCE 16 SEER2 AC 1.5 to 4.6 17600 to 55500 15.2 5.26 16.60

Take note that what we’ve estimated is the running amps of the air conditioner, not the starting amps. The AC starting amps can be 3 to 8 times the running current but only lasts for a short time.

Disclaimer: Remember, this is only a rough approximation. Others use amps per ton estimation, but the best way to know the current draw is to check the amp draw directly using a power meter or amp clamp or to read the nameplate of the appliance.

Factors Affecting Power Consumption or Energy Efficiency

1. SEER2 rating


The higher the SEER2 rating, the more efficient the air conditioner. This also means lower energy consumption for the same output.

2. Thermostat temperature


The difference between the outside temperature and the thermostat temperature also impacts power consumption. If the thermostat temperature is set too low, the air conditioner will need to work harder to meet the desired temperature.

3. Maintenance


A well-maintained air conditioner will function better than a poorly maintained one. Maintenance ensures that the ducts are clear, the air conditioner’s coils are clean, and the filters are free from buildup. Any of these factors may affect the efficiency of the air conditioner.

Tips for Reducing Air Conditioner Power Consumption


1. Set the thermostat comfortably high instead of low

Setting your thermostat low will consume more electricity. Set the thermostat to a higher comfortable temperature so that the air conditioner will not work hard as much.

2. Use a fan while using the air conditioner

A separate fan will help distribute the cold air the air conditioner releases. A fan’s electricity consumption is significantly lower than the air conditioner.

3. Warm or hot appliances should be far from the thermostat

The thermostat senses the ambient temperature and keeps the air conditioner running until the ambient temperature matches what you’ve set. Warm appliances like TVs or incandescent lamps can release heat that can be detected by the thermostat, extending the air conditioner’s running time.

How to Maintain the Efficiency of Air Conditioners


The following measures can be taken to maintain the air conditioner’s efficiency. If you are in doubt, you can ask a professional HVAC technician to do the maintenance regularly.

  1. Clean the AC filters.
  2. Clean the outdoor coils.
  3. Comb the coil fins.
  4. Unclog the condenser drains using a stiff wire.
  5. Check the window seals.

Frequently Asked Questions


How do I calculate the electricity cost for my 3-ton air conditioner?

We will modify our equation to calculate the estimated cost of running your 3-ton air conditioner. First, we’ll get the input wattage in kilowatts:

\[ \text{Input power in kW} = \frac{\text{Input power in watts}}{1000} = \frac{\text{Capacity in BTU/hr}}{\text{Efficiency rating} \times 1000} \]

Then, we solve for the cost using:

\[ \text{cost} = \text{power (kilowatts)} \times \text{operating time (hours)} \times \text{electricity rate} \]

For example, if we want to estimate the cost of running our 3 ton AC unit with SEER2 of 13.4 at constant high setting for 8 hours at the US average electricity rate of $0.17 per kWh, then our estimate may be:

\[ \text{Input power in kW} = \frac{\text{Capacity in BTU/hr}}{\text{Efficiency rating} \times 1000} = \frac{36000 \text{ BTU/hr}}{13.4 \times 1000} = 2.69 \text{ kW} \]

\[ \text{cost} = \text{power (kilowatts)} \times \text{operating time (hours)} \times \text{electricity rate} \]

\[ \text{cost} = (2.69 \, \text{kW}) \times (8 \, \text{hr}) \times (\$0.17 \, \text{per kWh}) = \$3.66 \]

An online amps calculator can also help you compute for your convenience. It can give you daily, monthly or yearly costs quickly.

Of course, this may depend on the previously discussed factors that affect how much is the AC unit drawing. Actual costs may be higher or lower depending on these factors.

How do I determine the right air conditioner size for my home?

A common rule of thumb is that you need around 25 BTU/hr for every square foot. Thus, a 3-ton air conditioner at 36,000 BTU/hr can cool a 1440 sq. ft. home.

However, several factors can impact the right size. These include the climate, the amount of sunshine, the number and age of the windows at home, and the number of people. A professional HVAC technician can accurately give you how many BTUs per hour you need for your home.

How will I know the amperage requirements for my 3-ton air conditioner?

The best way to know the amperage requirements is to check the nameplate of the appliance. The nameplate shows the total current, the minimum circuit ampacity, and the maximum breaker size. You can ask a professional HVAC technician or an electrician for the right installation requirements.


How many amps does a 3 ton air conditioner use? Based on the minimum SEER2 of 13.4, we estimated the amp draw to be around 12 amps. You can use this value to get a rough estimate of how much it would cost to run a 3-ton air conditioner.

However, a professional HVAC technician can give you a better estimate of power consumption, especially since power consumption depends on several factors. We suggest you contact them if you have your central air conditioning unit installed.

Read more: Amp usage of other devices such as a washing machine, an electric oven and etc.

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