Uploaded August 2026 | Updated September 2026, 3 weeks ago
Ty Branaman takes a classroom full of techs back to basics, walking through a full refrigeration cycle review before diving into how a TXV actually earns its keep. This one covers the fundamentals every tech should have locked in — from what's happening at the compressor discharge all the way around to superheat at the suction line — with plenty of back-and-forth Q&A along the way.
Ty breaks down subcooling, flash gas, and why a small percentage of liquid refrigerant has to sacrifice itself (turning to vapor) so the rest of the charge can drop from a hot liquid down to a cold saturated mixture almost instantly. From there, the group gets into how a TXV modulates to hold a constant superheat — and why it does NOT control suction pressure, no matter how often that gets blamed for a low-charge or airflow problem.
What's covered in this session:
Refrigeration cycle review — compressor, condenser, subcooling, metering device, evaporator, superheat
Why liquid refrigerant flashes off and absorbs heat at the metering device
How boiling refrigerant absorbs heat from the air (and why boiling is a cooling effect)
TXV operation, constant superheat, and common misdiagnoses
Sensing bulb placement, insulation, and mounting mistakes
Airflow measurement tools — Digital TrueFlow® Grid, DG-8 PRESSURE GAUGE, static pressure, and Measure Quick integrations
How airflow and humidity affect delta T, subcooling, and superheat
Compressor performance, compression ratio, and manufacturer performance data
This is a great refresher whether you're new to the trade or you just want to sharpen how you explain the cycle to an apprentice. Understanding airflow, subcooling, and superheat together — instead of chasing one number in isolation — is what separates a real diagnosis from a guess.
20° ΔT (Delta T), A Lazy Rule of Thumb HVAC school article: hvacrschool.com/20-delta-t-a-lazy-rule-of-thumb
Inverter Mini Split Operation and Service Procedures: acservicetech.com/mini-split-book
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
Ty Branaman takes a classroom full of techs back to basics, walking through a full refrigeration cycle review before diving into how a TXV actually earns its keep. This one covers the fundamentals every tech should have locked in — from what's happening at the compressor discharge all the way around to superheat at the suction line — with plenty of back-and-forth Q&A along the way.
Ty breaks down subcooling, flash gas, and why a small percentage of liquid refrigerant has to sacrifice itself (turning to vapor) so the rest of the charge can drop from a hot liquid down to a cold saturated mixture almost instantly. From there, the group gets into how a TXV modulates to hold a constant superheat — and why it does NOT control suction pressure, no matter how often that gets blamed for a low-charge or airflow problem.
What's covered in this session:
Refrigeration cycle review — compressor, condenser, subcooling, metering device, evaporator, superheat
Why liquid refrigerant flashes off and absorbs heat at the metering device
How boiling refrigerant absorbs heat from the air (and why boiling is a cooling effect)
TXV operation, constant superheat, and common misdiagnoses
Sensing bulb placement, insulation, and mounting mistakes
Airflow measurement tools — Digital TrueFlow® Grid, DG-8 PRESSURE GAUGE, static pressure, and Measure Quick integrations
How airflow and humidity affect delta T, subcooling, and superheat
Compressor performance, compression ratio, and manufacturer performance data
This is a great refresher whether you're new to the trade or you just want to sharpen how you explain the cycle to an apprentice. Understanding airflow, subcooling, and superheat together — instead of chasing one number in isolation — is what separates a real diagnosis from a guess.
20° ΔT (Delta T), A Lazy Rule of Thumb HVAC school article: hvacrschool.com/20-delta-t-a-lazy-rule-of-thumb
Inverter Mini Split Operation and Service Procedures: acservicetech.com/mini-split-book
Read all the tech tips, take the quizzes, and find our handy calculators at hvacrschool.com or the HVAC School Mobile App on the Google Play Store (hvacrschool.com/play-store) or App Store (hvacrschool.com/app-store).
