Video · HVAC Installation Craft
AC Startup Procedure: Weighing In Refrigerant on a New Trane System
The AC startup procedure is where a new install gets proven: refrigerant weighed in on a scale, pressures and temperatures read on digital gauges. This clip shows those steps on a new Trane condenser.
Job footageSwiftPro
- Topic
- HVAC Installation Craft
- Length
- 0:17
- Posted
- May 27, 2025
- Shot by
- The SwiftPro crew, Northern Virginia
What you’re seeing in this video
A new Trane condenser sits against a brick wall, freshly installed. On the ground beside it, a refrigerant cylinder rests on a digital scale, with hoses running to the unit's service valves.
The scale tracks exactly how much refrigerant leaves the cylinder, so the tech can add a measured amount instead of guessing. A digital manifold, the gauge set, shows live system pressures and line temperatures. Those numbers tell the tech whether the charge is right before the job is signed off.
Why it matters in your house
- Checking refrigerant charge is about more than pressure. A good tech compares line temperatures to calculate superheat or subcooling, which shows whether the system is charged correctly.
- A proper startup follows a deep vacuum. Before refrigerant is released, an HVAC vacuum pump pulls moisture and air out of the new lines.
- Ask for the startup readings. A company that records them gives you a baseline future techs can compare against.
What happens during a new AC startup?
After the lines are pressure tested and vacuumed down, the tech opens the service valves, adjusts the refrigerant charge by weight for the line set length, then runs the system and reads pressures, temperatures and amp draw. Superheat or subcooling confirms the charge. They'll also check airflow, the thermostat and the condensate drain.
Want it done at your place? See HVAC Installation Craft at SwiftPro or call (703) 997-9757.
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