| 3 - D Enterprises Incorporated | C20 + A, B, C8 +3 | 1991 | Active |
| 4 M Mechanical Inc | C20 | 2026 | Active |
| A / C Mechanical Sol Inc | C20 | 2008 | Active |
| A B M Building Services LLC | C20 + B | 2014 | Active |
| A C & H Mechanical Corp | C20 | 2017 | Active |
| A O Reed & Co LLC | C4, C20 + A, B, C16 +5 | 1931 | Active |
| A T S Heating And Air Corp | C20 | 2015 | Active |
| Abc Heating & Air | C20 | 2025 | Active |
| AC Sure Plan | C20 | 2022 | Active |
| Ace Contractors | C20 | 2017 | Active |
| Ace Coolers Inc | C38 | 2003 | Active |
| Ace Group Ki LLC | C20 + B | 2023 | Active |
| Aerco Systems LLC | C4, C20 | 2021 | Active |
| Aeris Mechanical Inc | C20 | 2013 | Active |
| Affordable Service Appliance Inc | C20 | 2007 | Active |
| Agair Enterprises Inc | C20 | 2022 | Active |
| Ahrens Mechanical | C4, C20 + A, B, C10 +6 | 2011 | Active |
| Air Plus Heating & Cooling | C20 | 1991 | Active |
| Airmaxx Inc | C20 + C10 | 2008 | Active |
| Akae Builder | C20 + B, C36, C42 | 2015 | Active |
| Alltech Solar Inc | C20 + B, C10, C46 | 1995 | Active |
| American Construction | C20 + B, C10, C36 | 2017 | Active |
| Andrade Cooling And Heating | C20 | 2025 | Active |
| Apex Mechanical Systems Inc | C20 + C36 | 2004 | Active |
| Arctic Airflow Heating & Air Conditioning Inc | C20 | 2023 | Active |
| Arenas Inc | C20 | 2024 | Active |
| Argo Performance LTD | C20 + C7, C10, D62 | 2015 | Active |
| Ascend Plumbing Inc | C20 + C36 | 2020 | Active |
| Atlas HVAC Inc | C20 + C36 | 2010 | Renew by Dec 31, 2026 |
| Atlas Mechanical Inc | C20 + C36 | 1991 | Active |
| Automatic Ice Makers | C38 | 1991 | Active |
| B S D Builders Inc | C4, C20 + A, B, C2 +3 | 2006 | Active |
| Becerra's HVAC LLC | C20 + B | 2003 | Active |
| Biosources Inc | C20 + B, C10 | 1997 | Active |
| Blue Mountain Heating And Cooling | C20 + C10 | 2020 | Active |
| Bluebay Mechanical | C20 | 2026 | Active |
| Blues Electric | C20 + C10 | 2020 | Renew by Dec 31, 2026 |
| Bob Jenson Air Conditioning Inc | C20 + C36 | 1977 | Active |
| Buckland Refrigeration Inc | C20, C38 | 2016 | Active |
| Build Brothers Inc | C20 + B, C10, C39 | 2014 | Active |
| Burtek Energy LLC | C20 + A, B, C10 +1 | 2016 | Active |
| By The Book Plumbing Heating Air Conditioning | C20 + C36 | 2021 | Active |
| C & S D Construction Inc | C20 + B | 2003 | Active |
| Cal - Cool Mechanical | C20, C38 + C55 | 1997 | Active |
| Cali Ice Inc | C38 | 2021 | Active |
| Casablanca Heating & Air Conditioning Inc | C20 | 1988 | Active |
| Caspian Glory Inc | C20 | 2023 | Active |
| Cass Plumbing & Heating | C20 + C8, C16, C36 | 1953 | Active |
| Castle Comfort | C20 + C36 | 2018 | Active |
| Chill Factor Mechanical | C20 | 2011 | Active |
| Classic Plumbing Heating & Air | C20 + C36 | 2025 | Active |
| Climate Heating And Air Conditioning Inc | C20, C38 | 2018 | Active |
| Climate Paradise | C20 | 2025 | Active |
| Colepepper Plumbing Inc | C20 + C36 | 2015 | Active |
| Collins Pacific Plumbing Inc | C20 + C36 | 1989 | Active |
| Comfort Air Conditioning And Heating | C20 | 2021 | Active |
| Comfort City Mechanical Inc | C20 + C36 | 2018 | Active |
| Communication Wiring Specialists Inc | C20 + C7, C10, C36 | 1991 | Active |
| Continental Construction & Development | C20 + B, C10, C16 +1 | 2005 | Active |
| Cool Guys | C20 | 2026 | Active |
| Coolfix Pro Inc | C20 | 2025 | Active |
| Cooper Mechanical Inc | C20 + B | 2011 | Renew by Nov 30, 2026 |
| County Burner And Machinery Corp | C4, C20 + D21 | 1976 | Active |
| Courtesy Plumbing Inc | C20 + B, C36 | 2008 | Active |
| Cross Breeze Heating & Air | C20 | 2019 | Active |
| Custom Heating And Air Inc | C20 | 2003 | Active |
| D C A C Air Conditioning | C20 | 2016 | Active |
| Dispatch Heating, Air Conditioning & Refrigeration | C20 | 2024 | Renew by Dec 31, 2026 |
| Dma Mechanical Inc | C20 | 2020 | Active |
| DMC Contractors | C20 + B | 2024 | Active |
| Duwright Construction Inc | C4, C20 + A, B, C10 | 2010 | Active |
| E T S Air Inc | C20 + C10 | 2016 | Active |
| E Z Breezy Contractors | C20 + B, C10, C36 | 2019 | Active |
| Eb Mechanical Services Inc | C20 | 2025 | Active |
| Eco Services | C20 + B, C2, C10 +5 | 1973 | Active |
| Ecotech Pro Inc | C20 + B, C17 | 2025 | Active |
| Empire Specialties | C20 + B, C2, C9 +3 | 2014 | Active |
| Envirotech Inc | C4, C20 + B, C7, C43 | 1994 | Renew by Nov 30, 2026 |
| Essential Plumbing | C20 + C36 | 2008 | Active |
| Everlast HVAC Corp Heating Cooling And Air Conditioning | C20 | 2026 | Active |
| Evo Air | C20 + C36 | 2017 | Active |
| Express Plumbing Heating And Air Inc | C20 + C36, D35 | 2010 | Renew by Nov 30, 2026 |
| Fahrenheit Design Inc | C20 | 2003 | Active |
| Final Touch Restoration | C20 + B, C10, C36 | 2025 | Active |
| Friars Heating And Air Conditioning Inc | C20 + C36 | 2019 | Active |
| G/K Plumbing & Heating Inc | C20 + C36 | 1981 | Active |
| Greater San Diego Air Conditioning Co Inc | C20 | 1983 | Active |
| Guthrie And Sons | C20 + B | 2006 | Active |
| Held Heating And Air Conditioning Specialists | C20 | 2013 | Active |
| Howe Bill Heating & Air Conditioning Inc | C20 | 2007 | Active |
| Husser Heating And Air LLC | C20 | 2025 | Active |
| HVAC Experts Inc | C20 | 2023 | Active |
| HVAC Service & Design | C20 | 2024 | Active |
| I2b Networks Inc | C20 + C7, C10 | 2008 | Active |
| Ideal Plumbing Heating Air Electrical Inc | C20 + B, C10, C36 | 1977 | Active |
| III In I Construction Inc | C20 + B, C10, C36 | 1996 | Active |
| Innovative Construction Services | C20 + B | 2007 | Active |
| J Metro Refrigeration Inc | C38 | 1983 | Active |
| Jackson & Blanc | C4, C20, C38 + B, C7, C36 +1 | 1960 | Active |
| JK Morgan Company | C4, C20 + C7, C10, D62 | 2008 | Renew by Nov 30, 2026 |