BTU’s listing on the data plate into tons, divide by 12,000. So, for example, a recommendation not to exceed 37,500 BTU would mean not to install larger than a 3-ton a/c system.

   Larger is not necessarily better when selecting an air conditioning system for your mobile home. The air conditioner serves two functions simultaneously: cooling and dehumidification. But when the a/c system is more powerful than the manufacturer recommends, the home is cooled down too quickly, and not enough air volume flows over the system’s cooling coils to remove sufficient moisture from the air to bring the indoor humidity down to a comfortable level. Homeowners with oversize a/c systems often try to solve their high indoor humidity problem by lowering the thermostat setting further, but a very cold thermostat setting can cause condensation to form at the registers (louvered vents that supply air to the rooms), compounding the problem further. The warning label, shown below, is one manufacturer’s attempt to help their home owners avoid installing an oversize system.

Since every degree that you lower the thermostat setting increases your cooling bill from 3 to percent, a system that has a high efficiency rating, but an inadequate dehumidification rating, may cause you to have a higher cooling bill.

    Here’s three questions that the Florida Department of Community Affairs recommends that you ask your air conditioning contractor:

  1. 1)Can you do a load calculation in order to size new equipment properly to my structure?

  2. 2)Does the equipment you are proposing meet Florida’s current efficiency requirements?

  3. 3)Since moisture control is so important for Florida’s climate, can the proposed equipment maintain an indoor relative humidity of 55 percent or below?

    If the data plate is missing or painted over, there is another option. You can download the Manufactured Home Cooling Equipment Sizing Guidelines, which includes a calculator chart produced by the Manufactured Housing Research Alliance in conjunction with the U.S. Department of Energy’s Energy Star program. Click below to download:


   First, measure the exterior of the manufactured home to calculate the square footage, then find the “sizing group number” for the location of the home in the set of attached maps and, finally, look up the recommended tonnage on the chart for the combination of the two variables. There are two recommended tonnages for each combination: the first one is the size for Energy Star rated manufactured homes (with upgraded insulation), and the second is for homes manufactured to HUD standards beginning in October 1994.

   Mobile homes manufactured before October, 1994, met a lower insulation standard and are not included in the chart. For older homes, we recommend consulting a licensed HVAC contractor.

   See our blog “What is the best air conditioner for a mobile home?” for advice on selecting the right type of air conditioner.


Here’s links to more of our blog posts with useful information about buying and owning a mobile home:

  1. Does it make sense to buy an older mobile home and remodel it?

  2. Where do I find the vehicle identification number (VIN) on a mobile home?

  3. How do I find out how old a mobile home is and who manufactured it?

  4. What is the life expectancy of a mobile home?

  5. What are the most common problems with older mobile homes?

  6. What is the right price for a used mobile home?

  7. What does the HUD tag look like and where do I find it on a mobile home?

While we hope you find this series of articles about home inspection helpful, they should not be considered an alternative to an actual home inspection by a local inspector. Also, construction standards vary in different parts of the country and it is possible that important issues related to your area may not be covered here.
© McGarry and Madsen Inspection


More blog posts about mobile homes and air conditioning:

  1. How can I tell if a mobile home is well constructed?

  2. How can I make my mobile home look more like a house?

  3. What do I need to know about buying a foreclosure mobile home?

  4. My air conditioner won’t turn on. What’s wrong?

  5. What is a “ton” of air conditioning?

  6. Why is there mold around the air conditioning ducts?

  7. What is the minimum SEER rating for a new air conditioner?

  8. How hurricane-resistant is my mobile home?

  9. How can I tell the difference between a manufactured home and a modular home?

  10. Can I paint the vinyl covered wallboard in a mobile home?

  11. What is the SEER of my old air conditioner?

  12. Do I need stairs at all exit doors from a mobile home?

  13. What does “AUX HEAT” and “EM HEAT” mean on my thermostat?

  14. Does an addition to a mobile home have to comply with with HUD Code?

  15. What’s the difference between a manufactured and a mobile home?

  16. What is a Park Model mobile home?

  17. How can I know if my mobile home meets HUD Code?

  18. Can I install a mobile home myself?

  19. Where are the load bearing walls in a double-wide mobile home?

  20. Where are Wind Zone 2 and Wind Zone 3 for mobile homes located?

  21. What can I do to prevent moisture problems in my mobile home?

  22. Why are there cracks in the wallboard in a mobile home after its moved?

  23. What year were mobile homes required to become more storm resistant?

  24. What is wrong with an air conditioner when the air flow out of the vents is low?

  25. Can you move a mobile home that is 20 years old in Florida?

  26. What is a pit set mobile home?

  27. Does a single-wide mobile home have interior bearing walls?

  28. Is 7 feet a normal height for a wall/ceiling in a mobile home?

  29. Do you have any tips for buying a used mobile home?

  30. Why is the floor tile cracked in my mobile home?

  31. Why is it important that a mobile home stay level throughout its lifetime?

  32. How much venting is required for mobile home skirting?

  33. What do I need to know about building an addition to a mobile home?

  34. What is the average lifespan of a wood deck?

  35. What is an air conditioning heat recovery system?

  36. What is the average lifespan of an air conditioner?

  37. When should I switch the thermostat to “EMERGENCY HEAT” for my heat pump air conditioner?

  38. Why does the air conditioner condensate drain line need a trap in it?

  39. What is a D-sticker mobile home?

  40. What is the life expectancy of a modular home?

  41. How do I upgrade my old (pre-1976) mobile home to meet HUD standards?

  42. When was the first double-wide mobile home manufactured?

  43. How energy efficient is a mobile home?

  44. What are the most common problems with wall/window air conditioners?

  45. What are the HUD requirements for selling a remodeled or renovated mobile home?

  46. How many mobile/manufactured home manufacturers are licensed to sell their homes in Florida?

  47. Can a mobile/manufactured home get termites?

  48. What are the limitations on homesites where a mobile/manufactured home can be located?

  49. What does a home inspector look for when examining a mobile home crawl space?

  50. How do I look for mold in my mobile home?

  51. What is the difference between the electric service to a mobile home and a site built home?

  52. How can I make my mobile home more energy efficient?

  53. How much is a used mobile home worth?

  54. What would cause half of a double-wide mobile home to lose electric power?

  55. What are the common problems to look for when buying a mobile home that is older than 40 years?

  56. How many manufactured/mobile homes are there in the United States?

  57. Can I convert a shipping container into a HUD-Code manufactured/mobile home?

  58. How do HUD-code mobile/manufactured home standards compare to the IRC building code for site-built homes?

  59. What are the right words for the parts of a mobile/manufactured home?

  60. What is the right humidity level in a mobile home?

  61. Can you do a mobile home inspection with no electric power or water?

  62. What is the difference between a manufactured/mobile home water heater and a regular water heater?

  63. What is an “RP” sticker for a mobile home?

  64. What is a manufactured home?

  65. What is the building code for mobile/manufactured homes in Florida?

  66. Where do I find the VIN/serial number on a very old (pre-1976) mobile home?

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