Freezing in HVAC Systems 3D

Freezing in HVAC Systems 3D

In this 3D video, we look at the causes and effects of freezing in HVAC systems (buildup of frost or ice on the equipment).

Water freezes at 32°F or 0°F. When a surface, such as an evaporator coil, is below water’s freezing point and contains moisture, frost or ice may form on that surface. In many cases, freezing in HVAC systems starts at the evaporator coil and works its way out; freezing can happen when the suction saturation temperature stays below 32°F for an extended period of time.

Some HVAC/R applications, such as commercial freezers and heat pumps in heating mode, need to operate under below-freezing conditions; the formation of frost or ice will hinder heat transfer over time, and periodic defrosting will be required. Evaporator coils in cooling mode should NOT freeze; when freezing happens, it will block system airflow. In general, evaporator coils will be about 35°F below the return air temperature.

The rate at which freezing occurs will depend on the amount of moisture in the air, the length of time at which the evaporator coil temperature is below freezing, the temperature of the return air, the air velocity, and the overall coil design.

When you encounter a frozen system, allow it to defrost completely before troubleshooting. You may allow the system to defrost by leaving it off with (or sometimes without) the blower running. In some cases, you may be able to use a heat gun or run the heat pump in heating mode for a short period. Be mindful of the water as the ice melts and take steps to prevent water damage.

A low evaporator coil temperature may be caused by low load (low airflow and/or low indoor temperature), refrigerant undercharge, low outdoor ambient temperatures, blower issues, and refrigerant side restrictions. We can prevent low load by advising customers not to set their thermostats below 72°F in cooling mode on standard equipment. We can also prevent low airflow from being a factor by making sure we replace dirty filters and clean the evaporator coil and blower wheels as necessary. When freezing happens due to a low refrigerant charge or a restriction, we may also notice high superheat; in humid climates, freezing of this nature can cause the entire system to freeze up.

Comments

8/12/23 at 04:26 PM

Slightly off topic, I apologize.  However, I've been reviewing all your videos and podcasts for discussion of EEV's.   I'd like to see a tutorial/lecture/video (any of the above…:-) ) that discusses the consequences on gauge (pressures hi-lo side/temperatures hi-lo side) measurements when an EEV and an inverter driven compressor are present in a system.   In other words: I understand how to diagnose problems when the system uses a fixed orifice, I'm pretty comfortable with diagnosis activities when the system uses a TXV….. but the emergence of EEV's and throttling compressors is making the interpretation of gauge readings a bit more confusing to me…. I suspect other techs are having difficulty here too.   Any pointers ?   Are you thinking of preparing a "back to basics" video for these modern Air Conditioning Systems?  (Think Mitsubishi/Trane for example….)?    Thanks for all you do, it is absolutely amazing!!!!…. I look forward to your response…. Thanks -Skip- tfsbj7@gmail.com

    9/7/23 at 11:27 PM

    Hi Skip,

    I can completely relate to feeling confused about how to interpret refrigerant pressures on systems with EEVs and Inverters. I can’t say that I have all the answers but I have two pieces of advice. If the equipment is one of the major US brands (trane, lennox, carrier, goodman) and it has an inverter, there is typically a check charge mode that you can access through the thermostat. At that point you can diagnose it like a traditional system. if there is a problem with the EEV, you’re going to have to dig into the manufacturer’s literature to follow their diagnostic procedure.

    If you’re working on a mini split, I recommend getting a copy of Craig Migliaccio’s “Inverter Mini Split Operation and Service.” It’s the only book I know of that handles mini splits as a whole, vs. a brand specific approach. This book may help you understand how mini splits ramp up and down, and how they behave when they are running with low charge, high charge, etc.

    I hope that helps

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