| John Padilla Plumbing | C20 + C36 | 2021 | Active |
| Johndow Air | C20 | 2026 | Active |
| Johnnys Hvac-Sd Inc | C20 | 2016 | Active |
| Jy Mechanical LLC | C20 | 2023 | Active |
| KGS Electric Inc | C20 + C10 | 2020 | Active |
| Landmark Mechanical | C20 | 2021 | Active |
| Lighter Living Co | C20 + C36 | 2014 | Active |
| Lobo Heating & Air Inc | C20 | 2026 | Active |
| M&M Controls Inc | C20 + C7 | 2006 | Active |
| Mechanical System Contractors Inc | C20 | 2006 | Active |
| Merrick & Associates Inc | C20 | 1984 | Active |
| Merz Construction Inc | C20 + B, C8, C10 +5 | 1985 | Active |
| Morey Plumbing | C20 + C36 | 2011 | Active |
| National Air & Energy | C4, C20 | 1995 | Active |
| North West Alarms Inc | C20 + C10 | 2020 | Renew by Dec 31, 2026 |
| North Wind Heating & Cooling Inc | C20 | 2025 | Active |
| Novix Mechanical Inc | C20 | 2016 | Active |
| Omega Air | C20 | 2026 | Active |
| One Hour Heating & Air Conditioning | C20 | 2023 | Active |
| One Stop Comfort Center Inc | C20 + B, C10, C36 | 2022 | Active |
| P C I General Construction | C20 + B, C36 | 2007 | Active |
| Pacific Coast Air Inc | C20 | 2014 | Active |
| Pacific Rim Mechanical Contractors Inc | C4, C20 + B, C2, C36 | 2002 | Active |
| Patriot Air Air Conditioning & Heating LLC | C20 | 2016 | Active |
| Peak Air Heating And Cooling | C20 | 2025 | Active |
| Performance Automation Solutions Inc | C20 + B, C7, C10 +2 | 2010 | Active |
| Permon Contractors Inc | C20 + B | 2006 | Active |
| Pipe Trades | C20 + C36 | 2014 | Renew by Nov 30, 2026 |
| Plumbing & Air Star Heating | C20 + A, B, C36 | 2019 | Active |
| Point Loma Electric, Plumbing, Heating & Air | C20 + B, C10, C36 | 2009 | Active |
| Powers Plumbing | C20 + A, B, C10 +1 | 2006 | Active |
| Preferred Pros Heating And Cooling | C20 | 2020 | Active |
| Prime Air Solutions | C20 | 2022 | Active |
| Pro2call Commercial Refrigeration Inc | C38 | 2018 | Active |
| Proper Appliance Repair Inc | C20 | 2022 | Active |
| Protemp Solutions LLC | C20 | 2026 | Active |
| Q E Construction Inc | C20 + B, C10 | 2002 | Active |
| R W Smith & Co | C38 | 1984 | Active |
| Rally Air LLC | C20 | 2025 | Active |
| Refrigertion Engineering Inc | C38 | 1996 | Active |
| Reliable Standard Group LLC | C20 | 2023 | Active |
| Reliable Temperature Control LLC | C20 | 2026 | Active |
| Right Way Air & Heating | C20 | 2025 | Active |
| Robertson Mechanical Inc | C20 + B, C36 | 2010 | Active |
| Rockstar Plumbing Heating And Air Inc | C20 + B, C36 | 2013 | Active |
| RR HVAC Inc | C20 | 2016 | Renew by Nov 30, 2026 |
| Rsi HVAC LLC | C20 | 2026 | Active |
| RSM Mechanical | C20 | 2024 | Renew by Nov 30, 2026 |
| Saffa Contracting Co | C20 + B, C36 | 2025 | Active |
| Sam's Heating And Air Conditioning Inc | C20 | 1994 | Active |
| Same Day Heating Cooling & Plumbing | C20 + C10, C36 | 2025 | Active |
| Same Day Heating Cooling Plumbing | C20 + C10, C36 | 2019 | Active |
| San Diego AC Man LLC | C20 | 2026 | Active |
| San Diego Air Comfort Heating & Air Conditioning Incorporated | C20 + B | 2021 | Active |
| San Diego Air Conditioning | C20 | 2018 | Active |
| San Diego Backflow Testing | C4 + C12, C34, C36 +1 | 2019 | Active |
| San Diego Boiler | C4 | 2025 | Active |
| San Diego Cool Air Inc | C20 | 2021 | Active |
| San Diego Heating And Air Inc | C20 | 2026 | Active |
| San Diego Mechanical Energy | C20 + B | 2014 | Active |
| Schaeffer & Son's HVAC Services | C20 | 2012 | Active |
| Sdair | C20, C38 + B | 2010 | Active |
| Sharpe Refrigeration Inc | C38 | 2008 | Active |
| Siberian Side Inc | C20 | 2025 | Active |
| Skilled Mechanical Solutions LLC | C20 | 2025 | Active |
| Sky Clean Air Inc | C20 | 2018 | Active |
| Stable Temp HVAC | C20 | 2026 | Active |
| State Mechanical Systems Inc | C20 | 2023 | Active |
| Strong Construction Co Inc | C20 + B, C8, C9 +7 | 1974 | Active |
| Sunline Heating & Air | C20 + B | 2026 | Active |
| Superior Air Inc | C20 + C10 | 1993 | Active |
| Supreme Air Services Inc | C20 | 2005 | Active |
| Surefit Heating & Air Inc | C20 | 2019 | Active |
| Surf Bros HVAC | C20 | 2023 | Active |
| T L Services Inc | C20 | 2004 | Active |
| Tam Mechanical Inc | C20, C38 | 2017 | Active |
| Tech Air | C20 | 2014 | Active |
| Tha Heating Air & Plumbing | C20, C38 + A, B, C36 | 1997 | Active |
| The White Glove Guys, Plumbing Drains Heating Air Conditioning | C20 + B, C10, C36 +1 | 1987 | Active |
| Thermodynamic Heating & Air Conditioning Inc | C20 + C10 | 1993 | Active |
| Thorough AC | C20 | 2019 | Active |
| Top Rated Home Remodel And Design | C20 + B, C36 | 2022 | Active |
| Unimaster Inc | C20 + C10, C36 | 2002 | Active |
| United Electric Plumbing Heating & Air | C20 + B, C10, C36 | 1976 | Active |
| West County Mechanical | C4, C20 + B, C36 | 2008 | Active |
| Western Environmental Systems Company | C20, C38 | 1930 | Active |
| Wrights Heating And Air | C20 | 1999 | Active |
| Zed Electric | C20 + B, C10 | 2025 | Active |