Senior HVAC Mechanic - Washington, DC

M.C. Dean is Building Intelligence®. We design, build, operate, and maintain cyber-physical solutions for the nation’s most recognizable mission critical facilities, secure environments, complex infrastructure, and global enterprises. The company’s capabilities include electrical, electronic security, telecommunications, life safety, automation and controls, audio visual, and IT systems. M.C. Dean is headquartered in Tysons, Virginia, and employs more than 7,000 professionals who engineer and deploy automated, secure, and resilient power and technology systems;

and deliver the management platforms essential for long-term system sustainability.

Our people are inspired by the way engineering and innovation enhance customer outcomes, improve lives, and change the world for the better. We are driven by our core values of agility, expertise, and trust.

Applicants selected will be subject to a government security investigation and must meet eligibility requirements, including U.S. Citizenship, for access to classified information; ability to obtain & maintain HSPD & Secret, preferred HSPD-12 & Secret Active.

• Hold a current Journeyman License from a U.S. state or territory OR
• Possess a VMET certification with equivalent experience OR
• Have equivalent training and certifications, along with a verifiable minimum of 5 years of experience in a commercial or industrial environment where a license was not required (e.g., a Department of Defense)

M.C. Dean seeks a Senior HVAC Mechanic to troubleshoot, maintain, and repair commercial HVAC and central plant systems in a mission-critical environment. This role requires independent diagnosis of complex failures and technical guidance for junior technicians.

• Refrigeration and DX: Diagnose faults using pressures, temperatures, superheat, and subcooling; perform leak detection, recovery, nitrogen pressure testing, micron evacuation/decay testing, charging, component replacement, and nitrogen-purged brazing.
• Chillers and cooling towers: Troubleshoot air- and water-cooled chillers, flow deficiencies, safeties, and interlocks; interpret differential pressures, temperature differences, approach/range, and alarms. Service tower components and coordinate water treatment.
• Hydronics and pumps: Diagnose air binding, cavitation, flow and heat-transfer problems; service seals, bearings, couplings, strainers, and valves; verify alignment, rotation, vibration, expansion tanks, and system pressures.
• Boilers and steam: Troubleshoot heating equipment, heat exchangers, steam traps, pressure-reducing stations, and condensate returns; understand burner sequences, flame safeguards, low-water cutoffs, and interlocks.
• Air distribution: Service AHUs, fan coils, VAVs, reheat, exhaust, and CRAC/CRAH equipment; diagnose airflow, static pressure, humidity, coil freezing, and condensate problems; understand economizers and building pressure.
• Electrical and BAS: Troubleshoot motors, contractors, relays, overloads, control circuits, and VFDs using electrical meters. Interpret BAS trends, alarms, sensors, actuators, staging, lead/lag, resets, and commanded versus actual operation.

• Perform preventive/corrective maintenance and emergency repairs; identify recurring failure causes, recommend corrective work and spares, and verify safeties, operating sequences, and post-repair readings before return to service.
• Coordinate approved shutdowns, restoration, vendors, and BAS changes with leadership and Work Control; guide technicians and record findings, labor, materials, and follow-up in Infra Link/CMMS.
• Follow lockout/tagout, electrical safety,…