AC Not Working? Try This If Your House is Not Cooling Down.
It’s mid-July in Phoenix, AZ and the temperature will reach 112°F today for the 14th day in a row. Unfortunately, the forecast in our area is 119°F by this weekend. As you might expect, air conditioning companies like Magic Touch Mechanical are getting bombarded with emergency service requests this week. The most common messages we receive are, “my AC is not working,” “the AC can’t reach my thermostat setting,” “my house is not cooling down,” and, “my house is too hot.”
My AC is Not Working vs My AC Can’t Reach My Thermostat Setting
Having owned Magic Touch Mechanical for over 26 years, I know there’s a difference between these two symptoms. Let’s break them down one at a time.
My AC is Not Working
When a customer calls and says my AC is not working at all, we escalate it to an emergency repair. If your AC unit won’t turn on or is blowing warm air, there is obviously a problem that needs diagnosis.
Of course, an AC not working at all can be caused by any one of dozens of issues. It could be as simple as a blown fuse (which the service technician would investigate why the fuse blew). It could be something as serious as a refrigerant leak or compressor failure. Or any one of a hundred issues between a minor issue and a major one.
Even after 36 years working as an air conditioning service technician, I wouldn’t know the cause of the failure until I tested everything in person. Although the day is coming when every AC unit is equipped with self-diagnostic tools, we’re still not quite there yet.*
*Several AC manufacturers are building equipment with onboard diagnostics & even monitoring plans. I’m yet to see one that’s ‘nailed it’ yet – especially at a reasonable price.
My AC Can’t Reach My Thermostat Setting
While an air conditioning service technician will still need to diagnose, sometimes the AC is the problem, sometimes it’s not.
You would think an air conditioner not reaching its thermostat setting is always because the AC is not working, right? Let’s review a few scenarios and you’ll see why a house that’s not cooling down isn’t always a broken AC. First, let’s start with scenarios where the reason you’re not achieving your thermostat setting is the AC not working.
Failing Fan Motor, Run Cap, Start Cap, or Other Electronic Component
A ‘failing’ part is different than a ‘failed” part (and why routine AC maintenance is necessary – to spot ‘failing’ parts). I’ll use a failing condenser fan motor as an example. A condenser fan motor doesn’t always just ‘die’. When it does the service call message from our customer changes to, “AC not working”. However, when it’s ‘failing’, the customer often notices the AC is not reaching the thermostat setting but says, “the AC is still working”.
In the failing fan motor example, typically what is happening is the fan motor is overheating & shutting down intermittently. Once it cools down, it starts running again until it overheats again. This can happen repeatedly for hours, days, weeks, and even months. What’s happening in this scenario is the AC stops working, starts working, stops working, starts working. Hence, the reason the house is not cooling down to the temperature setting, even though the AC ‘appears’ to be working.
PRO TIP: We regularly get calls to cancel a service request because, “the AC is working again”. 99% of the time we get a call back within days with the message, “the AC is not working again”. Don’t cancel your appointment! The cost of a service call is worth knowing for sure, as they say, better safe than sorry. Using the failing fan motor example above, the compressor is at risk of severe damage if left unchecked. That service call could be the difference between less than one hundred dollars and thousands of dollars.
Now let’s review a scenario where the AC not working service call, is NOT caused by a broken AC.
My House is Too Hot & Not Cooling Down
We reviewed a scenario where a home not cooling down (achieving the thermostat setting) was the AC not working properly. Now let’s discuss conditions that can lead to a house getting too hot when it’s not an AC unit breakdown.
The Air Conditioner Can’t Keep Up During the Summer
Some of the AC service calls Magic Touch technicians will go to this week won’t be caused by the AC not working. The air conditioning equipment itself will all be running up to the manufacturer’s specifications. Here are a few scenarios where the thermostat setting can’t be achieved, and the home is not cooling down at no fault of the AC unit itself.
Load Calculation Design Temperature
An AC unit should be sized based on something called a load calculation aka heat gain analysis. A load calculation takes many variables into account beyond just the size of the space (square footage) being cooled. Some of these variables include, insulation R-Values, window & door U values, orientation of the home, and many more. Even the types of blinds you have, number of occupants, and roof type & color, are factored into the calculation.
All those factors are calculated to determine the air conditioner size needed for a specific “design temperature”. Depending on where in the Phoenix area you live the design temperature will vary slightly. Note, every city in the world has a different design temperature and is mostly determined by historical temperature & humidity data. In most cities near Phoenix, the design temperature is 75°/108°. What that means is the unit is sized to be able to maintain a 75°F indoor thermostat setting when it’s 108°F outside. (I’m oversimplifying it as other conditions play a role, but you get the gist).
When it’s 112° outside today it will be 4° hotter than the 108° design temperature. If we do hit 119° this week it will be 11° hotter than design temperature. Many homeowners (me included) keep their temperature setting below 75°. Let’s look at a scenario.
It’s 119° outside at 4pm, the thermostat setting is 72° inside. In this scenario the AC unit is trying to reach a setpoint that’s 14° outside of what was designed to do. Depending on many other variables, it simply may not be able to reach or maintain that thermostat setting.
Thermostat Setting Issue
For this scenario, let’s use that same 119° day. It’s fair to say these are “extreme” conditions, right? Now let’s say you set your thermostat to 82° when you leave for work. You arrive home at 5:30pm and set it to 75°. Everything in your home including your furniture, walls, floor, etc. is going to be around 82°. Your ac unit now must cool everything down 7° with an ambient temperature that’s already 11° above the design temperature. In other words, there’s an 18° spread to cover! Again, it’s not quite that simple, I’m oversimplifying it to demonstrate why it’s not “this piece of junk” AC’s fault.
PRO TIP: You may not be saving energy at all by setting your thermostat up to high during the day. In fact, you may be using more energy than if you had only raised your thermostat setting 2-3°. Your AC unit must work harder, longer, and often when usage rates are the highest to bring the temperature down. This is especially true during period of extreme temperatures like Phoenix is experiencing as I write this article.
The House is Not Cooling Down Because It Can’t!
We covered some of the variables that are input into a load calculation aka heat gain analysis above. As the name implies, we are calculating how much heat the home will gain (allow to enter the home). The name of the game is to do everything you can to allow as little heat gain into the home as possible!
For example, simply installing solar shade screens aka sun screens on your windows will dramatically reduce heat entering your home. Adding attic insulation to increase the R-Value (R = Resistance to Heat) is another worthwhile investment with a quick ROI.
Getting the Cold Air There
A common issue in Phoenix homes is poor duct design & installation, and/or leaky ductwork. The ductwork is one of the most important elements of the air conditioning ‘system’. It’s not uncommon to find a home is not cooling down to the thermostat setting due to ductwork related problems.
AC Not Working? Try This If Your House is Not Cooling Down.
I purposely added, “try this if your house is not cooling down” to the title of this article. I did this in defense of every AC unit out there working it’s butt off to keep us all cool! Why, because as you now know, sometimes the ‘AC not working’ has nothing to do with the unit itself.
You now know you may have to think differently about your thermostat settings, install some window sunscreens, or add insulation. Maybe you need to have your air ducts sealed, repaired, or even redesigned and replaced. You also may need to schedule routine AC maintenance or become a service agreement member.
All of these are things you can “try” to improve your family’s comfort and the icing on the cake is you’ll save money on your energy bills too. By the way, I practice what I preach and not only have done all the above in my own home, but my house also stays icy-cool with low electric bills – even during the extremes!
AC Not Working? AC Not Cooling Down Your House? – Just Call Magic Touch!
If you live anywhere within a 35-mile radius of our main office in downtown Mesa, AZ we service your neighborhood! We can help you with any of your home comfort needs from fixing an AC that’s not working, to installing shade screens , insulation, or ductwork. Schedule an appointment today and see why our tagline is, There’s Magic in the Air!
Magic Touch Mechanical
There's Magic in the Air! Since 1997