#cooler

Tech Tips:

Why Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or just parts of the […]

Walk-In Cooler Defrost

This article is a quick, real-life diagnosis/find by Kalos Services senior commercial HVAC/R tech Eric Mele. Improper Defrost Timer installation While servicing this display cooler for an unrelated problem, I noticed the defrost timer installed in a way that will almost certainly cause early compressor failure. Because this is a cooler (not a freezer), it […]

Elton Harman
#cold control #cooler #Defrost #freezer #paragon #refrigeration #timer

Check out our most recent video

How to Evacuate an AC system, Full Vacuum Procedure

Our latest Podcast

HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this short Q&A podcast episode, Bryan answers a listener-submitted question about circuit board troubleshooting: is there a quick way to learn how to check circuit boards, and if so, where are those resources?

A circuit board is a bunch of components put together on a printed circuit board (PCB). There isn’t a lot of helpful universal information about circuit boards available, as they vary quite a bit by model and manufacturer. However, many of the basic components will be the same across circuit boards: microprocessors, diodes, relays, capacitors, and transformers. If you understand what these are on their own, that will help you understand what they do in circuit boards.

You mostly need to know the inputs, outputs, and sequence of operation of a circuit board to diagnose it. The sequence of operation tells you when certain things are supposed to happen, such as in an integrated furnace control (IFC); the flame rectification process is a classic example. If the flame can be proven, the operation continues; if it can’t be proven, then that will cause a lockout (possibly due to improper grounding or poor placement and NOT necessarily because of the board).

A lot of issues with the board can be diagnosed if you understand the inputs and outputs (e.g., 24v signals) or observe it with your senses, such as bloated capacitors or ant nests. Becoming a master of the obvious and checking the manufacturer’s literature are the top two things you can do to diagnose circuit boards.

HVAC Control Systems by Ronnie Auvil

Electricity for Refrigeration, Heating, and Air Conditioning by Russell Smith

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android