This is How to Successfully Troubleshoot an AC Unit

how to troubleshoot an AC unit

Breaking Down the Parts of a Air Conditioning System

Technicians just starting in the field have many questions about the process required to troubleshoot an AC unit.  In this series, I’ll break down the major parts of an AC system. But first, let’s go through a simple service call to figure out why the AC in question is not working.  Then we can get into more details in this series once we know what’s going on.

To successfully troubleshoot an AC unit, let’s start at the thermostat and go all the way to the outdoor unit turning on and the blower turning on, forcing air into the rooms of your house.

The Thermostat

When your house reaches a point where the AC needs to come on, a series of components work in a specific order to produce cold air.  So, go ahead and turn on the air conditioner.  Set the temperature down below what the temperature of the room is now.

Taking this step will make two switches inside the thermostat close:  the Y and the G terminal.  Y is for cooling – it turns on the outdoor unit, and G is for the air handler’s blower fan.

At this point, I always check the filter to make sure it’s clean.  Without a clean filter, your system can’t breathe in, so it won’t be able to breathe out, sending air into the house.

The Air Handler

Let’s go to the air handler first and see what’s going on there.

At the air handler or furnace, the control board is what’s calling the shots.  It receives the signal from the thermostat for Y and G to energize the terminal block.  If you put your meter leads on the C and Y terminals, you’ll get 24 volts.  Between C and G, you’ll get the same.

G is going to send the signal to the relay switch on that same board.  The closed switch tells the blower motor to come on.  It allows the 120 volts from the correct blower tap to start turning the blower wheel.  The blower motor on these units will have a capacitor on it. See my video below outlining the steps to test it.  On models made after 2019, blower motors became a little more advanced and energy-efficient.  Digitally commutated motors like this don’t use a capacitor.

The only other thing going on up at the air handler is the cold evaporator coil has refrigerant moving through it. There’s a metering device at the coil, but we’ll address that in another segment in this series.

Some furnace and coil combos have a condensate safety switch wired into the control board.  The air conditioner creates condensation that drains out to the side of the house. This switch provides a safety device that stops the air conditioner from producing any more condensation should the drain clog up.  See my video on this topic as well, below.

The Air Conditioner

Now let’s get out of this hot attic and head out to the air conditioner!  Technicians must be safety conscious at the AC.  Two hundred forty volts flowing through your body is no fun but regularly happens to people who aren’t qualified to work on it.

Let’s see what should be happening at the air conditioner when you take the panel off.  That Y signal from the air handler connects to the contactor, which pulls in, allowing the 240 volts from the house onto the compressor and condenser fan motor.  The compressor will pump the refrigerant to and from the outdoor coil and the indoor cold coil we talked about earlier.  The condenser fan motor keeps the outdoor unit cool by sending the heat from inside the house out of the AC unit’s top.

From here, the AC will provide about 18 to 22 degrees cooler air than is going into the return side of the system.  If it’s not and the air is reaching that temp split, you may need to check the refrigerant charge and start doing some more in-depth troubleshooting of the compressor and more, which is just what this series will explore.

Troubleshoot an AC Unit: Improving Your Skill Set

As a new technician, you don’t have to be intimidated by all kinds of moving parts and thermodynamics.  Yes, when you get down to the details about it, you’ll need to have a greater skill set, which means more training – and hopefully, this series will provide that for you.

Thanks so much for stopping by, and we’ll see you at the next blog post!

Don’t miss our videos related to this topic:

4 AC Add-ons That Will Make Your Life Easier When it Gets Hot This Summer

4 air conditioner add-ons

Beat the Heat This Summer with Modern AC Enhancements

When it gets hot this summer, there are a few things that could make your system last longer, be safer for your house or your family, and just be plain old convenient for your home.  With today’s technology, your HVAC system doesn’t have to be so, well, old fashioned.  Here are a few add-ons to bring some life to your air conditioning system.

Wi-Fi Thermostat

Homes everywhere are still equipped with old fashioned thermostats that you have to turn on and off manually.  For the last several years, Wi-Fi thermostats like the Honeywell 9000 are making it much more convenient to turn on the AC.  You buy the thermostat for a couple of hundred dollars, put it on the wall in place of your old one, download the app, and enjoy the ease of operating your AC from the comfort of your Lazy Boy chair in the living room.  You can read more about these devices here.  Heck, as long as you have connectivity, you can change the temperature of your home from Puerto Rico!  This is a state-of-the-art AC enhancement.

Honeywell Wifi Thermostat
compressor start kit

HSK

Compressor start kits are one of the air conditioning add-ons I believe in with all of my heart.  We add these devices to your outdoor AC unit.  It connects to the high voltage side of the power circuit, so make sure a licensed technician does this work for you.  The compressor in your outdoor unit pumps the refrigerant in your system to create cold air for your home.  Next to your car engine, it’s the most challenging motor to get started in your home.  I know a compressor start assist kit will not only ease the initial start-up of the motor thousands of times every summer but will add years of life to one of the most expensive appliances in your home.

Condensate Safety Switch

Some people have an HVAC system where the “cold coil” is in the attic.  A myriad of errors can occur when your AC is operating that can cause a back-up of water or a clog, which eventually could overflow and send water down onto the sheetrock below it.  That’s your ceiling!  If you’ve ever had to repair a small portion of your ceiling because of damage, you know how hard it is to match the texture and paint.  And if it’s not right, it can be a big eyesore for the homeowner.

Say you could buy some sheetrock insurance for a couple of hundred dollars…. would you do it?  Then getting a condensate safety switch is the perfect air conditioning add-on for you. It’s a low voltage device that continually monitors the condensate level of your emergency drain pan in the attic.  It will shut down the system preventing more water from accumulating and will alert you to call your HVAC professional.  Yes, your AC won’t operate during the error, but you also won’t face possibly thousands of dollars’ worth of water damage to take care of, either.

Condensate Safety Switch

What is a Condensate Safety Float Switch?»

Air Purification as an AC Enhancement

Everyone wants to breathe in nice clean air in their home.  The filter you change out every couple of months is keeping the big particles of air from entering the mechanical part of your HVAC system.  But it’s not going to be able to get rid of tiny single-cell viruses, multi-cell bacteria, mold, and spores that develop in many homes all around town.  Getting an air purification device is the AC enhancement that addresses this.  There are different technologies to choose from, but once you narrow it down to the one you want, I know you will be breathing much cleaner air in your home every day.
iWave air purifier

Get Started with Your Air Conditioning Add-Ons

If you’d like to have a conversation with us about any of these items for your AC system, click on the Book Your Online Appointment button at the top of the page to set up an appointment at your convenience.  I talk about these AC enhancements because I use them for my own.  I know they will add years of life to your system, be safer for your house, and simply be more convenient for your home.  We hope to hear from you soon!  Take care.

Don’t miss our video related to this topic:

The Importance of a Condensate Safety Switch

condensate safety switch

Water Damage Protection for Your Sacramento Home’s Ceiling

Too many times, we’ve gone out on a service call and found that the ceiling is flooding with water. Sheetrock is bulging from the ceilings, ductwork is saturated, or insulation is wet and pressed up against the sheetrock.  Left over time, it can start to create mold.  Water Damage Abatement teams are brought in to dry up the house in an effort to keep everyone healthy.  Floor coverings need to be replaced, and more.  All this can be prevented with the help of our little friend, the condensate safety switch.

Your air conditioner has a hot coil outside and a cold coil inside. The cold coil inside has a fan blowing room temperature air across those cold coils.  That causes condensation, which on normal occasions flows down the main condensate drain with the help of gravity, and out the side of the house where you normally see the pipe dripping with water in the summertime.  That’s normal!

If that primary drainpipe were to ever clog, or a family of mud wasps built a nest in that drain pipe.  Nothing even needs to happen for it to clog, the bacteria and gunk that builds up in ¾ inch PVC pipe is so disgusting, it will clog itself.

Checking the Pipe

What you don’t want to see is the secondary or emergency drain dripping with water.  Where is that one located?  Normally it terminates above a window around your house.  Check for it around your eaves and you’ll see it.  If you see water coming out of that pipe, call your favorite AC company and they’ll likely come out with compressed nitrogen and clean that line out for you.  It takes quite a bit of pressure to really clean that thing out, so let’s leave it to the pros.  People can really hurt themselves trying to mess with compressed gasses.

Back to the drain pan.  A condensate safety switch is mounted on the side of your condensate drain pan or directly to your secondary drain port on the evaporator coil.  There’s a float inside the switch that will rise if the water level of the pan fills up with a certain amount of water.  So, when that normally-open switch closes, the contacts energize at a low voltage and send a signal to the control board to shut down operations.

A Condensate Float Switch Provides 24-Hour Protection

The reason you should have one of these for your home is that it provides a 24-hour watchdog to make sure your overflow or emergency pan doesn’t fill up with water.  I know it’s supposed to be there for overflow, but you really don’t want this thing filling up with water.  Imagine that coil draining water down; trickle, trickle, trickle.

Do we want that happening outside the house draining to the grass, or do we want that drip, drip, dripping down on our sheetrock on the ceiling above our heads?  This happens way too often in Sacramento.  And don’t think you’re off the hook because your system is in the closet or garage.  If those system’s pan fills with water, then it will overflow and come down onto the control board down below as well as the blower motor.  That’s an easy 1000 dollars in repairs; and a furnace that might never quite work the same.

Peace of Mind

Other people have found this inexpensive item to be a real lifesaver.  I’ve been selling these safety switches since I first started HVAC in 2010.  People seem to like the peace of mind they get knowing there is something watching their condensate drainage in the attic, so it doesn’t come through the ceiling.  If mounted properly and inspected every year for proper operation, it will last for many years.  Hopefully, you never need to use it, right?

Some people don’t think these will fit their HVAC system.  I’m here to tell you, there is a condensate safety switch for every single evaporator coil out there.  Whether your system is in the attic, closet, or garage, the potential for the primary drainage to clog and back up is almost 100%.  It’s going to happen.  It’s really just a matter of when.

Protect Your Home with a Condensate Safety Switch

Folks who practice routine maintenance on their system have no idea what I’m talking about because they’ve never had a clog.  The valve is really just another smart thing you can add on to your HVAC system that didn’t already come with it.  Your HVAC technician will choose the right switch for your system, install it, and wire it to the furnace control board.  If you are not a licensed technician, you could really injure yourself or your property unknowingly by installing this safety switch improperly.

Don’t let this happen to you.  It’s expensive to repair your ceiling, let alone to match the texture on the ceiling at that particular spot.  It’s a real art form to be able to do that.  The switch installation is a small price to pay for sheetrock protection.

Check out my video on this topic below.  It goes over the basics of the safety switch and shows me installing one at a house.

I hope this answers your questions as to what a condensate safety switch is and how it can work for you and your home.  Fox Family offers a lifetime warranty on this inexpensive product.  If you’d like us to come out and take care of that for you, email us or give us a call at 916-877-1577.

Thanks so much and see you on next week’s topic!

Don’t miss our video on this topic: