Air Conditioning Compressor Basics

Air Conditioning Compressor Basics

This video is the ultimate guide to air conditioning compressor basics. Bryan explains how an A/C compressor works, what an air conditioning and refrigeration compressor does, and what it needs to do its job.

Compressors come in all sorts of types, including reciprocating, scroll, rotary, screw, and centrifugal compressors. All types increase the pressure of vapor refrigerant; they all decrease the volume to increase the pressure, which causes it to move.

Many compressors are powered by electrical plugs (often made of Fusite), which connect to the motor on the inside. Compressors generally have three different designs for varying degrees of accessibility: hermetic (sealed), semi-hermetic (bolted), and open-drive (where the compressor is separate from the motor).

Compressors can only compress vapor, not liquid. We check the superheat to make sure we’re only sending fully vapor refrigerant to the compressor; sending liquid to the compressor can damage it. The suction gas temperature is also important to ensure that the compressor head is being cooled adequately (for refrigerant-cooled compressors) and to make sure the mass flow rate is good.

Mass flow rate also plays into compression ratio, which is the ratio of absolute discharge pressure to absolute suction pressure. The compression ratio is a measure of how efficiently a compressor is pumping; too much compression indicates a lack of efficiency (such as through re-expansion).

Compressors have oil inside their crankcase, and a small amount of oil circulates with the refrigerant. Oil control is very important, as compressors have bearings that need to stay lubricated. If liquid refrigerant gets into the compressor, it can cause foaming and oil loss, which can lead to increased mechanical wear and possible premature failure over time. When liquid refrigerant migrates to the crankcase during the off cycle, it can create a flooded start that causes a lot of oil loss. (Crankcase heaters, liquid line solenoid valves, and hard shutoff TXVs can all help prevent flooded starts.) Overheating can also cause the oil to break down.

When the compressor increases the refrigerant pressure, it also increases the refrigerant pressure because the molecules move more quickly in a smaller space. For the most part, the heat content stays the same (with the exception of some minor contributions, such as from the motor windings) despite the temperature increase.

Comments

Most popular videos

See all +
thumbnail

Tips for Cleaning an Air Conditioning Common Drain

thumbnail

Gas Furnace Overview w/ AC Service Tech

thumbnail

Motor Overload and Safeties – Kalos Meeting

thumbnail

A Common Electrical Mistake

thumbnail

5 Traits of Bad HVAC Leaders

thumbnail

Don’t Overfill Refrigerant Recovery Cylinders The Easy Way

thumbnail

How to Replace an AC Condensing Fan Motor

thumbnail

How to Braze Air Conditioning Copper

thumbnail

How to Leak Test an AC With Nitrogen Pressure

thumbnail

How to Properly Pipe a Drain on a Fan Coil

thumbnail

4 Silly Mistakes of The Green HVAC Tech

thumbnail

How to Install an AC Disconnect

thumbnail

Why a Hard Shut Off TXV Closes

thumbnail

The Importance of SST (Evaporator Temperature) and Using a Scale (Kalos Meeting)

thumbnail

Adjusting Gas Pressure on a Standard and Gemini Furnace Valve

thumbnail

How a Heat Pump Reversing Valve Works

thumbnail

Don’t Confuse TD & Delta T

thumbnail

How to Install a Thermostat

thumbnail

How and When to Use a Schrader Core Removal Tool

thumbnail

Why Does The Evaporator Coil Freeze (And How to Diagnose It)

thumbnail

How to Measure Total External Static Pressure (TESP)

thumbnail

Does a TXV Shut under Vacuum?

thumbnail

Prevent this Common Manometer Mistake

thumbnail

Facts About Fusite (Compressor Electrical Pass Through Connections)

thumbnail

See Inside a Biflow/Heat Pump Filter Drier

thumbnail

Flammable Refrigerant Safety Basics – Kalos Meeting

thumbnail

Stuck Contactor Issue

thumbnail

How is 208 volts different than 230/240 volts?

thumbnail

Tips for Hiring & Getting Hired

thumbnail

Open vs. Closed Refrigeration

thumbnail

How is a 3-Phase Motor Different than Single Phase

thumbnail

HVAC Class 11/24/2020 – Electrical Review

thumbnail

How to Measure Gas Pressure – Kalos Meeting

thumbnail

What is Common, Start and Run?

thumbnail

Perfect Flares Every Time w/ NAVAC NEF6LM

thumbnail

Ask Bryan Anything Live Call-in from 11/21/2020

thumbnail

How to Build a Sheet Metal Coil Case From Scratch

thumbnail

What Air Filter is The Best?

thumbnail

Basic Electrical Circuit Terms

thumbnail

The #1 Key to Service Success?

thumbnail

How To Keep Motors Running Cool And Efficient

thumbnail

Talk Through The Refrigerant Circuit Using The “Glass Tube” trainer

thumbnail

Top 10 HVAC Tech Tips for 100K

thumbnail

Installing a Rectangle to Round Transition into an Existing Metal Duct

thumbnail

How Humidity Impacts The Weight of Air

thumbnail

Testing Home Pressure Imbalance w/ Genry Garcia (Spanish)

thumbnail

Some of Bryan’s Favorite New Tools Giveaway Meeting

thumbnail

Bert Teaches The Basic Refrigerant Circuit + Safety

thumbnail

Heat Rise Airflow Calculation

thumbnail

LIVE Apprentice Q&A

thumbnail

Setting a Refrigerant Charge by Subcool

thumbnail

The Toxic SUPER TECH Mindset

thumbnail

Soft Skills Can Be Hard (Disciplines of Growth)

thumbnail

Double Crimp Connection

thumbnail

How to Fabricate a Metal Supply Plenum From Scratch

thumbnail

Delivered Capacity Basics – Kalos Meeting

thumbnail

Sequencer Facts – They Aren’t All The Same

thumbnail

Wire Routing & Float Switch Positioning

thumbnail

Dual Voltage and Part Start 3-Phase Motors

thumbnail

Apprentice Program Day 1 – Using Your Resources w/ Jason Obrzut

thumbnail

Bert Cleans Out His DIRTY Work Van (And You Should Too!) #BERTLIFE

thumbnail

Liquid Line VS. Discharge Line

thumbnail

Tips for Proper AC System Cleaning – Kalos Meeting

thumbnail

EPA 608 Prep – Type 3

thumbnail

Motor Replacement Tips & Tricks – Kalos Meeting

thumbnail

EPA 608 Prep – Type 2

thumbnail

Better Duct Installation Practices – Kalos Meeting

thumbnail

THIS Is How My FIRST WEEK As An HVAC Apprentice Went (I’m Being Trained By WHO?!)

thumbnail

EPA 608 Prep – Type 1

thumbnail

How to Find Refrigerant Leaks – Kalos Meeting

thumbnail

Advanced Ventilation w/ CERV2

thumbnail

Critical System Diagnosis for Residential HVAC

thumbnail

Diagnosing Open & Short Circuits

thumbnail

Installing a Mitsubishi One-Way Ceiling Cassette In An Unfinished Room (You Can See EVERYTHING!)

thumbnail

How to Use a Blower Door (Como usar el Blower Door)

thumbnail

How to Stop Drain Snot (Bacterial Zoogloea)

thumbnail

EPA 608 Core Prep – Part 2

thumbnail

EPA 608 Core Prep – Part 1

thumbnail

A Strange Contactor Issue

thumbnail

GreenSpeed Extreme Install

thumbnail

Symptoms of Low Evaporator Airflow

thumbnail

Preventing Flooding On a Walk-In Call

thumbnail

Symptoms of Overcharge

thumbnail

Diagnosing and Replacing a Run Capacitor

thumbnail

Symptoms of Low Refrigerant Charge

thumbnail

Preventing, Finding & Repairing Refrigerant Leaks

thumbnail

Proper Use of Manometers for HVAC Technicians

thumbnail

UV light and Petri Dish Demo

thumbnail

Tool Talk Live – Probes, Bags, Hand Tools, Power Tools & More

thumbnail

Cleaning BARD units with Venom Packs

thumbnail

Electrical Basic Concepts – RSES NATE Prep

thumbnail

Selling, Upselling, IAQ , Hardstart Kits and More

thumbnail

Cutting & Installing a Rectangle Duct Connection

thumbnail

How to Make a Leak Free Canvas Duct Connector

thumbnail

Cooling Commissioning Measurements Walk Through w/ MeasureQuick

thumbnail

How to Checkout Blower Settings Using a Manometer

thumbnail

Recovery Best Practices & Giveaway

thumbnail

Introduction to the Fieldpiece Joblink Manometer Set

thumbnail

HVAC SCHOOL MONEY TALK – Don’t Make This Common Mistake

thumbnail

Testing out a High Performance HVAC Installation

thumbnail

Commercial Refrigerant Retrofit Options in a Crisis Economy #LIVE

thumbnail

HVAC Myth Busting #2 – Volts Go Down, Amps Go Up

thumbnail

Rectorseal RSH 50 Installation

thumbnail

Setting Up Residential Demand Ventilation with Laser Egg

thumbnail

Residential Zoning Talk #LIVE

thumbnail

DUCTLESS Control and Humidity Hack with Cielo Breez

thumbnail

HVAC Myths and Controversy #1

thumbnail

Rectorseal Surge Protector Installation

thumbnail

HVAC Contractors Guide to COVID-19

thumbnail

Commercial Install Review

thumbnail

DIY Cloth Mask with HEPA Pocket

thumbnail

How to Make an Indoor Air Cleaner the Cheap and Easy Way

thumbnail

Electrical Diagnostic Thinking

thumbnail

Human Comfort Basics – RSES NATE Prep

thumbnail

Introducing Venom Packs

thumbnail

5 Install Mistakes that Kill Systems

thumbnail

UV Part 2 – Honest UV Facts from a Manufacturer

thumbnail

UVC Air Purification – Live Podcast Part #1

thumbnail

How to Make a Metal Duct Transition in the Field

thumbnail

Reversing Valves (RSES NATE Prep)

thumbnail

Sunday Coil Cleaning #BERTLIFE

thumbnail

Liquid Line Solenoid on Long Refrigerant Lines

thumbnail

Condensing Unit Install Practices (RSES NATE Prep)

thumbnail

HVAC Motor Types (RSES NATE Prep)

thumbnail

Relative Humidity in the Supply Air Stream

thumbnail

Advanced Combustion Analysis (HVAC) w/ Jim Bergmann

thumbnail

Advanced MeasureQuick Diagnosis w/ Jim Bergmann

thumbnail

How to Flow Nitrogen While Brazing

thumbnail

Compressor Tear Down (Don Gillis / Trevor Matthews)

thumbnail

Compressor Facts and Troubleshooting (Don Gillis / Trevor Matthews)

thumbnail

CO2 101 (with Don Gillis)

thumbnail

Nikki Krueger – The Dripping Point

thumbnail

Inside a Scroll Compressor

thumbnail

Troubleshoot a Grounded (Shorted to Ground) Compressor

thumbnail

Using Power Factor to Check Capacitors Under Load

thumbnail

Straight Cool Air Conditioning Schematic (Carrier)

thumbnail

Charging During Low Outdoor Ambient w/ Charging Jacket

thumbnail

Recovery Machine Speed Race 🏁NAVAC NRDD Digital vs. Appion G5 Twin

thumbnail

Is There Mold in my Ducks! 🦆(Ducts)

thumbnail

Inside a Sequencer

thumbnail

A thermostat miswire and distracted diagnosis #BERTLIFE

thumbnail

Cleaning large coils with CoilPro

thumbnail

Smelly Ductless #SOLVED

thumbnail

Inductive Reactance in Real Life

thumbnail

50K Subscriber Special & Behind the Scenes Tour

thumbnail

Compressor Won’t Run Diagnosis

thumbnail

A Blower and Heat Strip Dangerous Mistake

thumbnail

How to adjust a TXV, TEV or TX Valve

thumbnail

5 HVAC/R Terms That Sound Worse Than They Are

thumbnail

Fieldpiece Joblink Firmware Update Demo

loading

To continue you need to agree to our terms.

The HVAC School site, podcast and tech tips
made possible by generous support from