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Minnesota Department of Labor and Industry

Field installed air conditioning

Manufactured Structures Bulletin 24


Manufactured Home Dealers and Installers


Richard A. Brooks


January 1990  


Field Installed Air Conditioning 

Recent questions about air conditioning units installed in the field have prompted us to again express our concerns about the mixing of components. You need to be aware of the following requirements and cautions.


Do not mix components from different equipment manufacturers. There is no valid reason for doing it. Mixing components (controllers, cooling coils, condensors, and A/C Blowers) can bring the entire heating and A/C unit out of compliance with its listing when the combination of components, together, may not have been tested for safety as well as for their rated efficiency. When the equipment is out of compliance with its listing, the home is brought out of compliance with the Federal Standard and the Dealer and/or Installer are subject to penalties under MN. Stat. 327.35, not to exceed $1000.00 per violation or imprisoned not more than one year, or both.


Components can be mixed only when they have been tested together with the furnace for safety and rated efficiency. Written proof of such a test must be retained by the installer, and be part of the furnace listing. We have not seen any such test reports.


A permit and inspection for the air conditioning installation must be obtained when working in municipalities enforcing the State Building Code. The Dealer must verify this if the work is subcontracted and paid for by the Dealer.


A Minnesota Licensed Electrical Contractor must wire the air conditioner to the home. The Electrical Contractor must obtain permits and inspection. The Dealer must verify this if the air conditioning is included in the sale of the home to the consumer. MSBC 1350.3800.


All equipment and components installed in the field must be installed in conformance with their installation instructions. In most all known cases, when air conditioning is added to a furnace that is not "air conditioning ready", a larger blower is required. It is required because the air must be moved through the cooling coil and because cold air is heavier than warm air and harder to move. If a larger blower is not installed the system will not function properly. Reduced air flow will cause heating and cooling inefficiency and may be a safety hazard by not moving enough cool air across the heat exchanger. Raising the furnace temperature, causing the furnace to cycle on its high limit switch.


Warranties. Mixing of components may void the equipment manufacturers warranty. At the least it will cause the consumer problems should the installed equipment fail, such as failure of a furnace blower not manufactured by the furnace manufacturer. Who provides replacement during the warranty period? Most likely the consumer will not know who to contact.


Summary. This Division does not want or need another consumer complaint and we firmly believe the dealer and manufacturers feel the same way. That's why we are encouraging the use of original equipment manufacturers parts for air conditioning installations, or repairs to furnaces, especially those units still under warranty by the furnace manufacturer.

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