| 3d Heating And Air LLC | C20 | 2022 | Active |
| 4 Winds Mechanical Inc | C20 | 2019 | Active |
| 7 Days Heating And A/C Inc | C20 | 2006 | Active |
| A A A Electrical Services Inc | C20 + C10 | 1992 | Active |
| A C P Mechanical | C20 | 2013 | Active |
| Aaa AC & Heating Inc | C20 | 2023 | Active |
| Abc Plumbing Heating And Air Conditioning | C20 + C16, C36, C42 | 1981 | Active |
| Abc Quality HVAC Inc | C20 | 2024 | Active |
| Abel Air Inc | C20 | 2026 | Active |
| Abm Building Solutions LLC | C4, C20, C38 + B, C7, C10 +4 | 2012 | Active |
| AC Heating And Air Conditioning LLC | C20 | 2020 | Renew by Dec 31, 2026 |
| Ace Plumbing Heating & Air | C20 + C36, C42 | 1975 | Active |
| Acr Heating & Air | C20 | 2024 | Active |
| Advanced Comfort Air Solutions LLC | C20 | 2021 | Active |
| Affordable Plumbing Heating & Air Inc | C20 + C36 | 2022 | Active |
| Ag Air Conditioning & Heating Inc | C20 | 2026 | Active |
| Air Attack Heating And Cooling LLC | C20 | 2024 | Active |
| Air Cool Heating & Cooling Inc | C20 + B, C10 | 2007 | Active |
| Air Plus Inc | C20 | 2023 | Active |
| Airco Mechanical Inc | C4, C20, C38 + A, B, C2 +6 | 1975 | Active |
| Airsmiths Home Performance | C20 + C2 | 2010 | Active |
| All Year Inc | C20 + B, C2, C10 +1 | 1981 | Active |
| Alt AC | C20 | 2024 | Active |
| Ambient Air Solutions Inc | C20 | 2024 | Active |
| American Home Energy Savers Inc | C20 + B | 2017 | Active |
| American Nest HVAC | C20 | 2026 | Active |
| Antelope Heating & Air Inc | C20 | 2021 | Active |
| Arctic HVAC Solutions | C20 + B, C10, C36 | 2024 | Active |
| Atticman Heating & Air Conditioning Insulation Inc | C20 + C2, C10, C36 | 2018 | Active |
| Barraza Heating & Air LLC | C20 | 2023 | Active |
| Bates Construction Company | C20 + A, B, C10 +1 | 1990 | Active |
| Best Built Inc | C20 + A, B | 2011 | Active |
| Big ""o"" Mechanical LLC | C20 | 2025 | Active |
| Big Mountain Heating And Air Inc | C20 + B, C17, C36 +1 | 2006 | Active |
| Blue Forge Climate Solutions Inc | C20 | 2025 | Active |
| Blueman Air Inc | C20 | 2026 | Active |
| Bos Sheet Metal Inc | C20 + C43 | 1968 | Active |
| Brocchini Enterprises Inc | C20 + B, C10 | 2011 | Active |
| Brown's Heating And Air Inc | C20 + C36 | 2008 | Active |
| Buffalo Mechanical | C4, C20 + B, C2, C34 +2 | 2025 | Active |
| Building Maintenance Innovations Incorporated | C20 + B, C27 | 2010 | Renew by Dec 31, 2026 |
| Cabrerascooling LLC | C20 | 2026 | Active |
| Cal Oaks HVAC Inc | C20 | 2023 | Active |
| California Sheet Metal Inc | C38 + C43 | 2010 | Active |
| Capital City Comfort Inc | C20 | 2020 | Renew by Dec 31, 2026 |
| Capital Sheet Metal LLC | C20 + C43, D16 | 1951 | Active |
| Comfort Chilling Solutions Inc | C20, C38 | 2020 | Active |
| Comfort Systems Construction Inc | C20 + B, C10, C46 | 1988 | Active |
| Commercial Appliance Service LLC | C20, C38 | 2019 | Active |
| Community Resource Project Inc | C20 + B, C17, C36 | 1991 | Active |
| Cool Air Inc A | C20 + C10 | 2007 | Active |
| Cool Breeze Heating & Air | C20 | 2024 | Active |
| Cooper Oates Air Conditioning Inc | C20, C38 + C10, C36, C43 | 1991 | Active |
| D D K Mechanical Inc | C20 + B, C36, C43 | 2005 | Active |
| Delta Breeze Air Conditioning And Heating Inc | C20 | 2004 | Active |
| Di Cicco's Mechanical Inc | C20 | 2000 | Renew by Dec 31, 2026 |
| DRD Mechanical Inc | C20 | 2024 | Active |
| Ducks Plumbing Heating Air | C20 + C36 | 2017 | Active |
| E & L Builders LLC | C20 + B | 2026 | Active |
| Efficient Energy Solutions Inc | C20 + B, C2, C10 +5 | 1978 | Active |
| Elite Hvacr Solutions Corp | C20 | 2025 | Active |
| Ellis Heating & Air | C20 + C36 | 2004 | Active |
| Ellis L G Plumbing Inc | C4, C20 + A, C16, C34 +2 | 1979 | Active |
| Everbreeze Heating And Air | C20 | 2023 | Active |
| F A F Heating & Air | C20 | 2024 | Active |
| Fanman Inc | C20 + B, C10 | 2003 | Active |
| Foundation Four Construction LLC | C20 + B, C36 | 2026 | Active |
| Fox Family Heating And Air Conditioning | C20 | 2023 | Active |
| Freelance HVAC Inc | C20 | 2023 | Active |
| G5 Construction LLC | C20 | 2020 | Renew by Dec 31, 2026 |
| Gold Standard Heating & Air Inc | C20 | 2022 | Active |
| Green Home Heating And Air LLC | C20 | 2024 | Active |
| Greenhill Technologies | C20 | 2025 | Active |
| H L Mechanical Inc | C20 | 2020 | Active |
| Handy Heating And Air | C20 + B2 | 2021 | Active |
| Heim Boys Heating And Air | C20 + B2 | 2021 | Active |
| Hua Electric & HVAC | C20 + B, C10 | 2017 | Active |
| Iec Services | C20, C38 + A, B, C10 +4 | 2020 | Active |
| Indoor Environmental Services | C4, C20, C38 + C36, C43 | 1992 | Active |
| Indrieri Inc | C20 + B, C10 | 2023 | Active |
| Iron Mechanical Inc | C4, C20 + B, C2, C34 +2 | 2009 | Active |
| Ivy Heating And Air Inc | C20 | 2021 | Active |
| J C Mac Heating & Air Inc | C20, C38 | 1992 | Active |
| Jaecin Heating And Cooling Inc | C20 | 2019 | Active |
| Jaguar Heating & Air Inc | C20 | 2014 | Active |
| James Long Construction Services Inc | C4, C20 + B, C7, C36 +1 | 2003 | Active |
| Jerico Mechanical | C20, C38 + C10 | 1990 | Active |
| Kang Construction Inc | C20 + B, C10 | 2022 | Active |
| Kings Heating And Air | C20 | 2024 | Active |
| Kitchell / Cem Inc | C20 + B, C10, C36 | 2010 | Active |
| Kodiak Mechanical Heating & Air | C20 | 2026 | Active |
| Kvach Heating And Cooling Inc | C20 | 2016 | Active |
| Laris Heating & Air Inc | C20 | 2021 | Active |
| Lawson Mechanical Contractors | C4, C20, C38 + A, ASB, B +5 | 1958 | Active |
| Lawson Mechanical Contractors LLC | C4, C20, C38 + A, ASB, B +5 | 2023 | Active |
| Lawson SSP Group LLC | C4, C20, C38 + A, ASB, B +5 | 2023 | Active |
| Legend 72 Heating And Air | C20 | 2022 | Active |
| Legend Heating And AC Inc | C20 | 2026 | Active |
| M & Brothers HVAC Inc | C20 | 2026 | Active |
| M3 Mep LLC | C4, C20 + A, B, C7 +3 | 2022 | Renew by Nov 30, 2026 |