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Q&A – Vacuum Questions Answered

By Bryan Orr

In this episode of the HVAC School podcast, host Bryan dives deep into the topic of vacuum in HVAC and refrigeration systems. He addresses two questions from social media about vacuum, expanding them into a comprehensive discussion of best practices, common issues, and techniques for effective vacuum procedures.

Bryan starts by explaining where to ideally locate a vacuum pump when working on a refrigeration system. He emphasizes the importance of pulling from the largest volume locations possible, often at multi-position service valves on the compressor or wherever accessible ports are available. He notes that systems that have been in operation pose unique challenges due to refrigerant dissolved in the oil, which can significantly increase vacuum time.

The podcast then covers the “one hose method” for pulling vacuum, detailing the process of using a single large hose connected to the suction side with the core removed, while placing the micron gauge on the liquid side. Bryan explains how this method can be highly effective for new systems but may take longer for systems that have been in operation. He also discusses the importance of valve quality.

Key topics covered in the podcast include:

Ideal vacuum pump location in refrigeration systems
The “one hose method” for pulling vacuum
Challenges of vacuuming systems that have been in operation
Using heat and nitrogen to improve vacuum efficiency
Importance of quality valves and tools in vacuum procedures
Proper maintenance of vacuum pumps and micron gauges
Dealing with refrigerant dissolved in oil during vacuum
The science behind evaporation at the oil-vapor interface
Tips for speeding up vacuum in difficult conditions
Recommended resources for further learning about vacuum techniques

Get your copy of Review of Vacuum for Service Engineers at TruTech Tools HERE.

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Author:

Bryan Orr

Company: HVAC School

Position: Founder

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Topics Covered

Jim’s cancer diagnosis: non-Hodgkin’s B-cell lymphoma and the progression from standard chemo to aggressive relapse
CAR-T cell immunotherapy explained: how T cells are extracted, genetically modified, and reintroduced to fight cancer permanently
Jim’s recovery at the Cleveland Clinic and surpassing the critical six-month remission milestone
Neurotoxicity as a side effect of CAR-T therapy and what that experience was like
The pivot away from measureQuick’s per-use pricing model and the dramatic improvement in retention after switching
The “time to value” philosophy driving measureQuick’s new hybrid workflow interface
How measureQuick is integrating AI — and where AI falls short in real-world HVAC diagnostics
Label identification as the most practical current AI application in field diagnostics
Why AI is highly sycophantic and the danger of relying on subjective, internet-sourced training data for HVAC decisions
The power of measureQuick’s proprietary measurement data and target zones as a foundation for AI summaries
First-principle modeling and non-dimensional mathematics: why brand-agnostic diagnostics work
The importance of deploying all nine probes on every air conditioning service call
Benchmarking vs. commissioning vs. retro-commissioning: the three layers of equipment assessment
Design temperature difference: measuring evaporator and condenser delta-T as engineering benchmarks
How ECM motors mask airflow problems — and why that leads to premature motor failure and higher energy costs
The two “elephants in the room”: incomplete probe deployment and clearing faults without fixing them
Why clearing a fault in measureQuick without addressing the root cause is like putting duct tape over a check engine light
How poor installation practices in high-growth markets (Florida, Texas, Arizona, Las Vegas) have created widespread system deficiencies
The role of private equity in HVAC consolidation and why many PE firms add cost without adding value
Why implementing field measurement systems like measureQuick is the missing link for PE-owned and independent shops alike
The legacy mode vs. new mode toggle in the upcoming measureQuick update — no forced UI changes for existing users
How measureQuick helps newer technicians become productive faster and helps seasoned technicians be more consistent
The importance of presenting diagnostic findings to homeowners and helping them understand what the numbers actually mean