St. Marys and Calvert County Maryland HVAC Services   ♦   We Make Your Air Flow!

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Great Mills Heating and Air Conditioning, Inc. is a Southern MD, locally owned, HVAC contractor specializing in the repair, installation and servicing of Carrier home, residential, commercial, heat pumps, gas furnaces, propane furnaces, oil furnaces, water heaters, humidifiers and radiant heating. We also repair any make or model of heating and cooling comfort control system, heat pump or furnace.

About Us

Great Mills Heating and Air Conditioning was founded in June of 1972 by Charles E. Aud, Sr. We now have three owners: Charles E. Aud, Sr. (President), Kirk E. Kuginskie (Vice President) and Lisa M. Aud (Secretary/Treasurer). We are a Factory Authorized Carrier Dealer. Since 1972, we have been installing and servicing Carrier heating and cooling equipment, and improving indoor air quality in the St. Mary’s County and Southern Calvert County, Southern Maryland areas.

Our Technicians

Great Mills Heating and Air employs NATE-certified technicians who have proven their knowledge in the HVAC/R industry by passing specialized NATE certification tests. Choose Great Mills for superior installation and maintenance or service of your heating, ventilation, air conditioning or refrigeration system to get the job done right the first time. SMECO Recommends Great Mills Heating and Air as a heating and air conditioning contractor with Nationally Certified Technicians with proper insurance and licensing.

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Ask us about Geothermal Heating and Cooling Systems

Great Mills Heating and Air also installs geothermal systems for homes.

Geothermal vs. Ground Water vs. Water Furnace Geothermal energy has been used to heat and air condition buildings for several decades. Other terms for these geothermal systems include geo-thermal, geoexchange, ground-water, ground-water assisted, ground-water-source, water-to-water, and even water furnace heating and cooling. 

Geothermal heat pump technology taps the energy in the earth's surface and drive a heating and air conditioning system for both residential and commercial uses. The result is a green or natural heat pump that saves energy and benefits the environment.

Great Mills Air Conditioning

Phone: 301-994-0522 

Emergency Service after 4:30pm:


Financing for Heating & Cooling Heat Pump Systems Great Mills Heating and Air offers financing through Wells Fargo and also accepts all credit cards.

Free Estimate

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Google Reviews

J. Petrosillo
These guys were great! Honest and to the point. They didn’t try to pressure you into buying things like the other guys.

M. Periman
Fast, professional, kind.

Mark W
Excellent experience! Furnace not working and 20 degrees outside... Great Mills H&AC answered my call at 7:15 am. Setup the appointment for 8:00 am. Arrived at 7:50 am. 2.5 hours later problem fixed and heat back on. Technicians did an EXCELLENT job. Very professional. Total bill... Less than $200 including parts and labor for two technicians! AWESOME!!

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