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About Us

At A&GS Contractor Inc, our mission is to provide exceptional HVAC and refrigeration solutions. We aim to expand our services, empower our team members, and foster long-lasting relationships with our clients, guided by our core principles of integrity, quality, and family values.

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At [Company Name], we're not just here to provide a service - we're your committed partner

Our Story

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A&GS Contractor Inc traces its roots back to the humble beginnings of its founder, Tomas, who embarked on his entrepreneurial journey from a small town in the Dominican Republic. Armed with an engineering degree from Santo Domingo, Tomas ventured to Puerto Rico, where he would marry his wife, Marlie Bello.

Tomas epitomizes the American dream through his relentless work ethic and commitment to delivering top-tier services in the HVAC and refrigeration industry. His trajectory from an entry-level project engineer to the President of a prominent Puerto Rican division of a stateside-owned company speaks volumes about his dedication and prowess in the field.

Named after his sons, Alex and Gabriel Sierra, A&GS Contractor Inc is a testament to familial dedication and entrepreneurial spirit. The dream of a family business materialized when Alex joined the company in 2022, alongside Tomas' wife and daughter-in-law.

Fueled by a collective vision, Tomas, alongside his family, remains steadfast in their pursuit of expansion. Continuously adding new certifications, skilled laborers, and embracing emerging technologies, A&GS Contractor Inc stands as a beacon of excellence in service provision and industry support.

Meet the Team


 Founder and President

Tomas Sierra Lugo

Tomas has over 25 years of experience in the refrigeration and HVAC engineering industry. He holds a BSME in Mechanical Engineering from Instituto Tecnológico de Santo Domingo, and earned an additional certification from Kansas State University in HVAC & Refrigeration Engineering Technology. At A&GS Contractor Inc, Tomas has cultivated a reputation for the highest quality on the island and maintains meaningful relationships with suppliers and customers.


 Lead Engineer

Alex Sierra Bello, PE

Alex holds a master’s degree in Mechanical Engineering from the University of Illinois- Champaign-Urbana, with an emphasis in Thermodynamics. During his tenure at The Boeing Company in St Louis, he worked in structures on the F-15 defense program, before returning to Puerto Rico in 2022 to bring his expertise to A&GS Contractor Inc. Alex maintains a Professional Engineering license in Missouri and Puerto Rico with a specialization in HVAC and Refrigeration. 



Marlie Bello Obijo

Marlie has spent the last decade serving as the primary payroll specialist, accounts receivable, accounts payable, and secretary for A&GS Contractor Inc. Her dedication to customer satisfaction and her mastery of internal business operations has been the backbone of the company for many years. Marlie holds a bachelor's degree in Business Administration from the University of Puerto Rico - Bayamon, with an emphasis in Accounting. 


Government Contracts Specialist

Kendra Kelch

Kendra holds a master’s degree in Government Contracting and Procurement from the University of Dayton – School of Law. She maintains expert knowledge of the Federal Acquisition Regulations, and facilitates courses on contract management through the National Contract Management Association. She has over 10 years of stateside business experience, bringing a myriad of process improvement and operations skills to steer the company into a globalized future. 

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