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Problem: Will a larger blower motor help my air conditioning? My air conditioner does not seem to be blowing air very hard.

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Problem: Will a larger blower motor help my air conditioning? My air conditioner does not seem to be blowing air very hard.

Answer: I would like to recommend checking your furnace’s blower motor capacitor to make sure the capacitor is not weak. A weak motor capacitor can cause the blower to run slow. Please click here if you would like to see the capacitors that we sell. Some small appliance shops will test capacitors free of charge. I would also recommend that you check to make sure your blower wheel (squirrel cage) and the bottom of your air conditioner evaporator coil is clean before trying a larger motor.  I would recommend checking your refrigerant charge to make sure you AC is charged up properly. If your AC system is low on charge it will cause the coil to freeze up and cause a restriction in the air flow. Rule of thumb is the blower should produce 440 CFM (cubic feet per minute) of air per ton. On a two ton system that is 880 cfm. This usually calculates out to about a 1/4 to 1/3 HP blower motor. If you get too much cfm it is hard on the air conditioner, because it robs the air conditioner of the cool gas going back to the compressor to keep it running cool and you have to over-charge the AC unit to get the cool gas going back to the compressor. I usually need to add refrigerant to a system that has too large of a blower motor. You want to charge your system so that there is cool gas going back to the compressor and the suction line feels like a cold coke can right out of the refrigerator. The air conditioner should make a 15 to 20 degree difference in the ambient air. If you home is 75 degrees inside, the air coming out of the registers should be between 55 to 60. I hope I have answered you question. I have installed oversized blower motors before to get more airflow. I would not recommend going over 1/3 horsepower in your case. You would need to check the charge after you install the new motor to make sure you are getting the needed cool gas back to the compressor. Below we have a real good YouTube video produced by hvacrepairguy which shows how to replace a blower motor. Thanks to hvacrepairguy for making this informative video! Please click here if you would like to see other DIY videos on how to test capacitors and clean AC evaporator coils. If you have any questions please email us anytime at: support@arnoldservice.com or comment in our comments section below. We would love to help you out and have your business!

6 thoughts on “Problem: Will a larger blower motor help my air conditioning? My air conditioner does not seem to be blowing air very hard.

  1. Hi I have twoout of 3 bedrooms 2nd floor and they do not cool or heat very well. The HVAC is in the basement and it is an electric ac and gas furnace. Unit is 18 yrs old and original from the time the townhouse was built. The ac part was replaced about 5 yrs ago. Will a new HVAC system help these rooms? One company said I should put booster fans in the duct work to push the air to those rooms.

    1. Hi Deb! You should get your contractor to do a heat gain, heat loss and duct calculation before installing the new system. Then you will know if the new furnace and air conditioner will do the job or not. More than likely you do not have the right size duct work or number of ducts to heat and cool your upstairs properly. We are required here in Louisville, KY. to submit a heat gain, heat loss calculation to our code enforcement housing department before we can start work on a new installation and get a work start permit approved. Thanks so much for asking this question. Steve

  2. I live in a 45 y/o mobile home with central air (which was installed as an afterthought). Coleman Evcon model BPCH0301BA. The 12″ diameter flexible ducting from the unit has to travel at least 6 feet before it connects with the metal ducting that delivers the conditioned air to the vents. Airflow into the house is minimal. I have to run the unit constantly and block the windows with dark curtains to achieve a modicum of cooling. Could the distance it has to travel account for the loss of pressure? Would a bigger blower help? The motor currently in the unit is 1/2 hp. Thank you.

    1. Hi Ginger! Sorry you are having trouble keeping your home cool. If your home only has one supply duct that is 12″ in diameter then this could be the problem. A 1/2 horsepower blower motor should handle 3 to 3 1/2 tons of air conditioning. Most mobile homes only have 2 to 2 1/2 tons of air conditioning not unless you have a very large mobile home. There are lots of things that can cause poor air flow and poor air conditioning such as: dirty filter, dirty evaporator coil, dirty blower wheel, dirty condensing unit, under or over charge of refrigerant, duct work too small for air conditioner, air conditioner under-sized for the heat gain of your home. The installers should have done a heat gain heat loss calculation to determine the size of the air conditioner and the size of the duct work that should be installed in your home. I am sure they did not do this 45 years ago. You might try to get some of these items checked out. A larger blower motor might help, but if you only have one supply duct it still probably will not do that much good. Sorry that I could not give you a definite answer. Steve

  3. Stumbled upon this while researching a similar issue. I have a 1700 square foot home, with a full unfinished basement that I am in the process of finishing. There are no vents in the basement. The upstairs vents put out decent air, but I’m afraid when I run vents to the two new bedrooms, bathroom and the family room it won’t be enough. Wouldn’t a larger blower solve this IF it becomes an issue? Also, how many returns should the basement have?

    1. Hi Mr. Birkemeier! A larger blower motor could harm your air conditioner since the amount of air that the blower sends out determines what tonnage Air conditioning you should have. The duct size determines the amount of air too. Too much air going through too small of duct work creates noise. Most of the time a 1/3 horsepower blower motor will handle a 2 1/2 to 3 ton AC unit and a 1/2 horse power blower motor handles a 4 ton unit and a 3/4 to 1 horsepower motor will handle 5 tons of air conditioning. The air flow should be 440 cfm per ton. You could try a larger blower motor, but test the cool gas going back to the compressor on a warm day. What usually happens is you have too much air flow and you have to over-charge the unit to get the cool gas back to keep the compressor running cool. When you have to over-charge the AC it you do not get as good cooling because it raises the evaporator temperature and it is harder on the compressor pumping more refrigerant. Just keep a watch on the pressures and super-heat going back to the compressor if you do install a larger blower motor. Rule of thumb in a basement would be one supply in every room. Probably two in the larger family room and one return that is centrally located in the basement near the floor. You probably already know this, but do not install the return in the same room as the water heater and furnace. The return should be in the largest living space if possible. Best of luck on this project. Steve

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