| JS Mechanical & Construction Inc | C20 + B, C33 | 2025 | Active |
| JW Heating And Air Inc | C20 + B | 2008 | Active |
| Kasnet Builders Inc | C20, C38 + B, C10 | 2023 | Active |
| Ko-Am Refrigeration & Air - Con Co Inc | C20, C38 | 1992 | Active |
| Kuzbass Corporation | C20 | 2022 | Active |
| L A Seismic Construction Co | C20 + B, D12 | 2019 | Active |
| L.C Heating And Air Inc | C20 | 2021 | Active |
| La Brea Heating And Air Conditioning Co Inc | C4, C20, C38 + B, C10, C36 +1 | 1991 | Active |
| Lai's Lo - Temp Refrigeration Co Inc | C20, C38 + B, C10 | 2013 | Active |
| Lenco Air Conditioning Service Incorporated | C20 | 1973 | Active |
| Lighthart Corporation The | C4, C20 + A, B, C10 +5 | 1990 | Active |
| Lipson Plumbing & Heating Inc | C20 + C16, C36 | 1985 | Active |
| LK Air-Cooling Inc | C20 | 2022 | Active |
| LM Heating & Cooling Inc | C20 | 2025 | Active |
| Lucky Air Construction Inc | C20 + B, C10 | 2025 | Active |
| M & D Contractors Inc | C20 + B | 2009 | Active |
| M And M Cellar Systems LLC | C38 | 2011 | Active |
| Maintenance Concierge Inc The | C20 + B, C10, C33 | 2008 | Active |
| Mammoth Air Company | C20, C38 | 2022 | Renew by Dec 31, 2026 |
| Mantis Construction Corporation | C20 + B, C39, C51 +1 | 2024 | Active |
| Mectec Inc | C20 + A, B, C10 +1 | 2004 | Active |
| Mister Freze H V A C | C20 | 2019 | Active |
| Moore Air Inc | C20 | 2012 | Active |
| Muir-Chase Plumbing Co Inc | C20 + A, B, C36 | 1988 | Active |
| Myd HVAC Inc | C20 | 2023 | Active |
| Namu Group Construction Inc | C20 + B, C10, C36 | 2018 | Active |
| New Evolution A / C & Heating Inc | C20 | 2024 | Active |
| Nexus Construction & Design Inc | C20 + B, C10, C36 +1 | 2024 | Active |
| Nice And Cool Inc | C20 | 2011 | Active |
| Nordstrom Air Inc | C20 | 2018 | Active |
| Nuair Solutions LLC | C20 | 2026 | Active |
| One Stop Refrigeration Inc | C38 | 2009 | Active |
| P & S Mechanical | C20 + B, C33 | 2017 | Active |
| Pacific Asian Consortium In Employment | C20 + B, D65 | 2011 | Active |
| Pacific Climate Group LLC | C20 + B, C12 | 2026 | Active |
| Pardess Air Inc | C20 + B | 1999 | Active |
| Parker Boiler Co | C4 | 1979 | Active |
| Philmont Management Inc | C20 + A, B, C10 +2 | 2002 | Active |
| Precise Air Systems Inc | C20 + C10, C46 | 1982 | Active |
| Premair HVAC Inc | C20 | 2024 | Active |
| Pro Tech Air Inc | C20 | 2001 | Active |
| Professional Duct Cleaning Co | C20, C38 + B, D64 | 2013 | Active |
| Professional Technicians Heating & Air Conditioning Inc | C20 | 2018 | Active |
| Psychro Air Techs | C20 | 2025 | Active |
| R & I Heating And Cooling Inc | C20 | 2023 | Active |
| Reairco Air Conditioning Service | C20 + C10 | 2015 | Active |
| Red Lilly Plumbing Inc | C20 + A, C36 | 1963 | Active |
| Renkow Mechanical Inc | C20 | 2000 | Active |
| Royal Heating And Air | C20 | 2026 | Active |
| Ryan Mechanical Inc | C20 + B | 2010 | Active |
| S A HVAC & Appliance Repair | C20 | 2021 | Active |
| S K Cooling Inc | C20 + B, C10, C36 | 2016 | Renew by Nov 30, 2026 |
| Samwon Construction | C20 + A, B, C10 +4 | 2005 | Active |
| Sanic AC Multi Service | C20 | 2024 | Active |
| Sautman Steve Electric Inc | C20 + B, C10 | 1977 | Active |
| Sea Pac Engineering Inc | C20 + A, B, C10 +2 | 1993 | Active |
| Service Masters | C20 + C36 | 2015 | Active |
| Shepherd Construction | C20 + B | 2023 | Active |
| Sids Air Conditioning Heating And Refrigeration Inc | C20, C38 | 1996 | Active |
| Smith Roy E Plumbing Co Inc | C20 + C16, C36, C42 | 1958 | Active |
| Sol Air Conditioning & Heating Inc | C20 + B, C36 | 2006 | Renew by Dec 31, 2026 |
| Soroush & Associates General Engineering Contractors Inc | C20, C38 + A, B | 1991 | Active |
| Southwest Heating & Air Conditioning Inc | C20 | 2015 | Active |
| Stay Cool Inc | C20 + B, C2 | 2014 | Active |
| Steam Equipment Co | C4 + C10, C36 | 1995 | Active |
| Stewart R O Plumbing & Heating Co | C20 + C36 | 1959 | Active |
| Style Build | C20 + B | 2015 | Active |
| Surfas Incorporated | C20, C38 | 1979 | Active |
| Swift Hvac's Corporation | C20 | 2026 | Active |
| Tim Stivers Inc | C20 + B | 2001 | Active |
| Tim's Heating & Air Conditioning Inc | C20 | 1991 | Active |
| Toucan Home Solutions LLC | C20 + B | 2022 | Active |
| True Balance Heating And Air Conditioning | C20 | 2023 | Active |
| Ultimate Mechanical | C20 | 2021 | Active |
| Universal Roofing | C20 | 2020 | Active |
| US AC Power Inc | C20 + C10 | 2022 | Active |
| W T S Construction | C20 + A, B, C10 +1 | 2017 | Active |
| Walt Air Heating & Cooling | C20 | 2025 | Active |
| Warner Technologies Inc | C20 + B, B2, C10 | 1999 | Active |
| Wenfeng General Engineering | C20, C38 + A, B, C10 +2 | 2024 | Renew by Dec 31, 2026 |
| White Level Maintenance LLC | C20, C38 + C36 | 2026 | Active |
| Wittler Young Co Inc | C20 | 1960 | Active |
| Wittler-Young Service Co Inc | C4, C20, C38 | 1975 | Active |
| Woolsey H E Corporation | C20 + B, C10, C12 +1 | 1972 | Active |
| Woori Cool | C20, C38 + C36 | 2022 | Active |
| Yboa HVAC Mechanical Inc | C20 | 2023 | Active |
| Yee Phillip & Co Inc | C20, C38 + C10 | 2016 | Active |
| Ys Mechanical Inc | C20 + B | 2024 | Active |