Find your location


How Do I Check for a Dirty Evaporator Coil?

How Do I Check for a Dirty Evaporator Coil?

Posted by
Ed Miller on Thu, May 16, 2013

Almost all air conditioning units have an evaporator coil that serves the purpose of removing heat from the air that passes through the filters of the units and making the coolant liquid in the evaporator coils absorb the heat, thereby cooling the air. This is part of the fundamental working principle of any a/c system and thus it should be obvious that anything that causes the evaporator to malfunction would vastly hinder the proper operation of the device. The best way to deal with the issue is to contact a professional air conditioning and heating company like Snyder AC, Jacksonville, FL.

A dirty evaporator coil is not a simple thing to identify and tackle. This is because the evaporator is not a part that is open or easy to access – it is usually found deep within the bowels of the casing of the air conditioner unit. At the least, a few screws and maybe some plastic or metal casings will have to be removed to be able to reach the evaporator easily. It would be prudent to check the user or service manual of your product to correctly identify where the evaporator is and how to access it easily. Once the evaporator coil is identified and located, it is still not easy to identify if a dirty coil is the cause of the problem.

Check Air Pressure

One of the most commonly used methods to see if a dirty evaporator coil is causing a loss in performance is to check the air pressure at both the entry to the air vents that takes in room temperature air and also the pressure at the output of the air conditioning unit. Then compare the pressure difference between the two values to what it says in the instruction manual. If the values are off by a lot, then it is likely that the evaporator coils need cleaning.

Gauging Temperature

Another way to check for dirty evaporator coils is to gauge the temperature gradient in the air before and after exposure to the evaporator coils. A normal range of the drop in temperatures achieved should be close to 20 to 25 degrees Fahrenheit. If the values are below this range then it is a sure sign that build up sediments in the evaporator coils are affecting the system efficiency.

Checking the amount of current flowing through the leads of the supply fan of the evaporator is another identification method used by a lot of professional servicemen of air conditioning systems. A dirty and clogged coil will not allow the supply fan to keep the coolant moving at high volumes, thus due to a phenomenon called dynamic braking, the speed of the supply fan is reduced which in turn reduces the amperage of the fan terminals. There are specific tools designed for the purpose of checking the current levels in the supply fan, or one could alternatively use a standard multimeter while taking care to place the leads at the correct positions.

Once you identify with certainty that the evaporator coils are in need of a good cleaning, then it is best to contact a trustworthy and professional air conditioning and heating company who do repair work as well as installations. This will make sure that they have the prerequisite skills and experience to carry out a task like cleaning out the evaporator coils and changing the liquid coolant if required. This is not a simple task that can be carried out by laymen since coolants are usually poisonous or at the least partially toxic to humans as well as the environment and so contact your a/c service company in Jacksonville, FL to do a professional job for you.

Snyder A/C has the best professionals for the job. Founded in 1973, we have been serving the residents in Northern Florida for forty years, and our loyal clientele proves the dedication and standards of our work and our commitment to our customers to provide the best possible job.

where you’ll find snyder

Snyder Air Conditioning, Plumbing and Electric serves families across Florida. You'll find our technicians are just a short phone call away in neighborhoods throughout these counties:


  • Alachua
  • Baker
  • Clay
  • Duval
  • Flagler
  • Nassau
  • St. Johns


  • Broward
  • Martin
  • Miami-Dade
  • Palm Beach
  • St. Lucie

Customer Reviews

This was an exceptional experience! We woke up to our A/C on but not cooling (it was 6am and already 81 in the house). The person who set up our appointment was very nice, able to get us seen same-day, and let us know of some options to help save us money.

-Christy Cormier

The service from Sam and Chris was excellent! They were very knowledgeable and professional. They were able to answer all of my questions and completed all of my electrical issues. I will definitely use them again for future jobs. Thank you!

-Adrienne Beal

From the get go I could tell that the Snyder employees were truly professionals and didn’t push to make sales like other companies I’ve talked to my whole life. They took the time to explain so that I could make a decision. The installers and later the duct cleaners were very respectful during their work here. Thank you.

-Mike Daniels

Snyder Heating and AC is dependable, always on time and techs have always been courteous and knowledgeable. Emanuel was a great addition to the company. He was friendly and knew what he was doing. Thank you for great service.

-Linda Ackley

Snyder came in and did a total overhaul of our duct system. They had a great knowledge of what to do to make our home so comfortable! The technicians were all so professional and took great care of us! We’re so thankful for their expertise. Great and easy communication with the call center. We will definitely use them again!

-Crystal Hill

Snyder provided an amazing experience from start to finish. Most of us dread getting estimates with pressuring salespeople. Erik was a great guy, explained all my options and didn’t try to pressure me to act quickly! Justin followed up with my husband and I to offer further assistance in our decision. Again, no pressure, just helped with our follow up questions.

-Michele Bauer

Very prompt, professional, courteous, and cleaned up after repair. Had water line break in my front yard and no pressure. Very pleased and would highly recommend Snyder for all your plumbing, and AC needs. Thank you for making a rough morning get better with ease and professionalism.

-Chuck Jr.

Snyder was easy to get in contact with and had availability the next day. Clint came out and needed some parts so had to reschedule us for the next day for installation. He did a great job converting our old 3 knob shower to one. Looks great! Professional and courteous. 100% recommend this company, especially Clint.

-Nicole Hansen

Very thorough and professional Job

-John Ridenour

Excellent work. Hard worker. Highly recommend.

-Andre A

Professionalism You Can Count On
Schedule Your Air Conditioning Repair Today!

With our highly-skilled technicians & upfront pricing, you can trust the local Jacksonville, FL experts at Snyder Air Conditioning, Plumbing & Electric for 100% satisfaction, guaranteed on all Air Conditioning Repairs.