Your central air conditioning isn’t cooling your home very well. So you go to check the inside unit and, lo and behold, your central AC’s inside unit is frosted over! (Which you probably find strange considering it’s summer).
What could be the problem?
There are 2 main issues causing this.
Reduced airflow to the inside unit will cause the refrigerant coil to freeze up.
First, we’ll tell you what usually causes reduced air flow to the inside unit and then explain the science behind why reduced airflow would cause the unit to freeze up.
OK so those are some “to-dos”. But why do you need to do them? Here’s why restricted airflow causes the coils to freeze up.
The evaporator coil (tubes forming the A-shaped part of the inside unit) has cold refrigerant flowing through it. A blower pulls in air from your home and over that coil, cooling the air.
But when there’s little to no air flowing over the cold evaporator coil, it quickly frosts over because there’s less heat to absorb.
When it’s frosted over, air can’t easily flow through the coils (it’s a solid block of ice now), reducing airflow to your home.
Here’s an illustration: Imagine you have a cup of water and every hour you add 5 ice cubes into it. You also have a hair dryer blowing hot air over the cup. Obviously, the ice would melt after you add ice into the cup.
Now imagine that you put something in between the hair dryer and the cup while you’re still adding ice to the cup. Because there’s something blocking airflow to the cup, the ice isn’t melting. This would continue until the cup is completely full of ice.
That’s basically what’s happened to the inside unit.
Follow our instructions from before to make sure there’s enough airflow going over the coils.
This is the most common cause of a frozen evaporator coil.
When your AC system is low on refrigerant, pressure drops causing the evaporator coil to get abnormally cold.
So when returning air hits the coil, humidity/moisture from the air beads ups on the coil and quickly freezes. This continues until the evaporator coil is frozen.
If you’re low on refrigerant you also have a refrigerant leak.
That means you’ll need a professional to find the leak and fix it before adding more refrigerant.
Worst-case scenario: The leak can’t be fixed and one of the refrigerant coils needs replacing. This is an expensive replacement. So if your AC is 15+ years old, you should consider replacing it.
If the filter was not dirty and there were no problems with the supply or return vents, you most likely need to call a professional for AC repair help.
Nicholson Plumbing, Heating and Air Conditioning has a team of expert air conditioning contractors ready to help! If you live in the Framingham-area, contact us to schedule an appointment for AC repair!
For our 24/7 emergency service, call us at 508-858-5476.
Francis from Nicholson Plumbing and Heating was excellent. He was here to evaluate HVAC in our home. He was very patient and answered all my questions. He is also polite and easy to communicate with him. He explained technical concepts to me in layperson terms!
- Shelley S.
Nicholson offered what is possibly the best customer service I have dealt with in a home repair situation. I called them because I was looking to replace my very old furnace. They came out to do an initial estimate, and then came back when I had some further questions about my options. After installing the furnace, they ran into some problems with my air ducts. This happened on a Friday, and the problem was fixed by Monday afternoon. In addition to their excellent service, they did quality work at a fair price. I would recommend them to anyone looking for an HVAC company in the Framingham area!
- Melissa T.
Recently used these guys because my HVAC unit AC wasn’t working (first hot day of summer). Showed up on time, wore booties, fixed the unit. During the visit we talked about how my unit was having problems in the winter – which was resulting in NSTAR service calls of maybe 3-4 times per season (I am on a service plan with them). He was the first guy to tell me WHY the problem was happening, and HOW to fix it. I find it strange that all of the NSTAR guys etc. no one took time to point out how to fix the source of the problem…Very professional, smart. I would use them again, and plan to for the fix on my heating unit!
- Ben J.
Nicholson Plumbing, Heating and Air Conditioning is the best and most reliable source for electrical service. We are proud to be Mitsubishi Electric Diamond Elite Contractors, that have gone through extensive accreditation and training in order to provide proven high-quality service. Get in touch with us whenever you need to have electrical work done in Framingham!