History Header Image

History

Hill History 1936 - Present

Image

Hill proudly celebrated its 90th anniversary in 2026. Originally founded in 1936 as L.C. Kohlman, Inc., the company initially specialized in refrigeration maintenance. Less than a year later, James B. Hill, P.E., joined as the firm’s engineer. Shortly  hereafter, the company was selected as the local distributor for DuPont’s new Freon refrigerant, with national distribution rights.

During World War II, the company operated as a large servicing agency and installed major piping systems in defense plants. In 1946, Federal Ventilation Co. was established to provide sheet metal capabilities for the emerging air conditioning market. James B. Hill became president of both firms in 1961 and eventually acquired them.

Over the next fifty plus years, three generations of the Hill family, along with many  loyal and talented associates, guided the organization through significant milestones. Today, Hill stands as one of the largest specialty contractors in Illinois, employing over 1,000 people and generating more than $650 million in annual revenue in 2025.

1936 - 1946

L.C. KOHLMAN INC. FOUNDED IN CHICAGO

  1. 1937 - James B. Hill hired as Engineer at the age of 26.
  2. 1946 - Federal Ventilation Sheet Metal Company founded.
  3. Sheet metal shop established.

1961

JAMES B. HILL NAMED PRESIDENT

  1. James B. Hill became president of both firms (L.C. Kohlman, Inc. and Federal Ventilating Company) and initiated a purchase agreement

1970 - 1979

MOVE TO 4241 RAVENSWOOD, CHICAGO, IL

  1. 1975 - Plumbing group added.

1980 - 1989

GROWTH

  1. Warren Hill, P.E., becomes President.
  2. All firms put under Hill Mechanical Group banner.

1990 - 1999

EXPANSION

  1. Dedicated Pipe / Plumbing Fabrication shop established.
  2. L.C. Kohlman, Inc. and Hill / Wendt Corp. becomes Hill Mechanical Corp.

2000 - 2009

NEW LOCATION - CONTINUED GROWTH

  1. James B. Hill passes away.
  2. Bob Krier becomes President of Hill Mechanical Corp.
  3. 2006 - Moved to 138,000 square foot facility in Franklin Park, IL
  4. Total revenue exceeds $289 million with over 1,000 employees.

2010 - 2019

75 YEARS!

  1. 2010 - Franklin Park campus now a total of 27 acres.
  2. Hill/Ahern Fire Protection is established.
  3. 2011 - The Hill Group celebrates 75 years of growth and success, spanning three generations of the Hill family.
  4. 2012 - Aero Testing & Balancing joins Hill.
  5. 2014 - James B. Hill II named President.
  6. 2016 - Precision Control Systems (Indiana) joins Hill.
  7. 2018 - Hill/Ahern Fire Protection is now Hill Fire Protection.
  8. 2019 - Hill Indy office opened

2020 - PRESENT

CONTINUED GROWTH AND SUCCESS

  1. 2021 - Hill Fire Protection Chesterton Indiana office opened.
  2. 2022 - Hill Fire Protection Indianapolis Office established.
  3. 2022 - Hill Nashville office opened.
  4. Hill Group-Chicago Tribune Top Workplaces 2023 - #24
  5. 2024 - Aero Testing & Balancing rebrands to Aero Performance Group.
  6. 2025 - Aero Performance Group acquires CEPro, Inc.
  7. 2026 - Hill celebrating 90th Anniversary