Air Conditioner Troubleshooting A Helpful Illustrated Guide

Come July, Air conditioning is a necessity in Michigan, and life can be unbearable if your air conditioner breaks down. Repairs can be expensive, troubleshooting your air conditioner system may save you the expense of a service call. Therefore,  Regular maintenance will save you a lot of heartache, aggravation, and expense. Plus, it’s always a good idea to have some knowledge of your air conditioner and furnace system should you happen to call a dishonest technician.

alt="picture of a goodman air conditioner model gsx16 from Livonia Mi customer, serving air conditioner installation needs of Novi MI"

Some Common Air Conditioner Problems

Breakers or Fuses

The breakers and fuses protect your air conditioners compressor and motor from overheating and doing significant damage to the a/c unit and your home. Several things can cause the a/c breaker to trip frequently

  1. A Dirty Filter. The extra work to push air through a clogged filter can trip the breaker.
  2. Loose Electrical Connections. Changes in temperature can cause the wires to expand and contract inside the breaker box and thus become loose.
  3. Low refrigerant will also cause your system to work harder and possibly trip the breaker. See below for signs you may have a refrigerant leak.
A Dirty Filter on left and changes in temperature can cause the wires to expand and contract and come loose, either one can shut your a/c down
Dirty Condenser Coil

Condenser Coils

The big square caged box or rounded cage cylinder outside the home is called the condenser unit. It contains the compressor, fan, valves and switches, and the condenser tubing and fins.

A/C refrigerant absorbs room temperature air and transports the low-pressure refrigerant gas via copper tubing to the condenser unit where it enters the compressor. Therefore, turning it into a warm, high-pressure gas.

It then leaves the compressor and flows into the condenser coils, where the gas discharges much of the heat that was received from inside. The massive fan you have probably noticed on top blows air over the condenser coils, so the refrigerant inside the coils loses heat and changes to a liquid. It finally flows back to the home via more copper tubing into the expansion valve next to the evaporator coil.

If lawn clippings, cottonwood, or bird dropping are on the condenser unit hose it off with the garden hose. You may save a lot of time, aggravation, and expense by spending a couple of minutes keep your investment clean and running smooth.

.Additional Information: Evaporator Coils & Condenser Coils | What Are They and How Do they work

Air Conditioner Compressor

The compressor’s function is to compress the refrigerant gas and move it through the a/c system so that it can get rid of heat and humidity from the air.

When your compressor breaks down, it’s often one of the following reasons.

  1. Dirty coils.
    Dirt, debris and mineral scales build up on the condenser coil; your air conditioner can’t expel enough heat from the system, causing it to run non stop to cool the home. The compressor may overheat and fail from the added pressure and temperature.
  1. I have blocked suction lines.
    Damaged or blocked refrigerant lines can increase the pressure and temperature, resulting in compressor failure. If the a/c isn’t cooling the house as it should, this may be the problem.
  2. Low refrigerant charge.
    If the lines holding the refrigerant starts to leak via a pinhole or small crack, once the level becomes low your compressor will have to work harder to circulate enough refrigerate through your a/c system to cool the home thus putting additional wear and tear on your compressor and increasing your electric bill
  1. Too much refrigerant.
    If a technician recently charged your air conditioner and inadvertently added the wrong type or too much refrigerant, it could destroy the compressor.
alt= "Picture of a melted air conditioner contactor and a new contactor ready to be installed by the pro's at TNT Heating and Cooling located in South Lyon, Mi."


Air conditioners utilize a contactor to energize the compressor and condenser fan motor. In other words, A contactor is essentially a heavy-duty relay.  As contact points endure expected wear and tear. The contact point surfaces become rough and pitted.  Due to the flattening, the contact points may not draw together evenly.  Both conditions will create a high resistance path for current flow, creating on heat on the contact points, which can cause a total meltdown. Also, the additional resistance can create a voltage drop across the contact points leading to additional heat and eventually compressor failure.

Evaporator Coils

The cold air that is delivered to the home comes from the a/c’ s evaporator coil or referred to as evaporator core. Its function is to assist the refrigerant in absorbing the heat. You can recognize the coil by the long U-shape bent tubing which is usually made from copper pipe because copper conducts heat easily.

Even a fine layer of dirt or dust on the evaporator coil can cause several problems, including:

  1. Reduced heat absorption and cooling capacity
  2. Higher electric bills
  3. Increased temperature and pressure on the compressor
  4. Frost and ice buildup on coils
alt= "Picture of an evaporator coil from a Goodman air conditioner installed by the pro's at TNT Heating and Cooling located in South Lyon, Mi."
alt= "Central Air Conditioner Condenser Fan Motor installed by the pro's at TNT Heating and Cooling located in South Lyon, Mi."

A Faulty Condenser Fan Motor.

Located within the condensing unit houses — the compressor, condenser coil, and condenser fan motor.  The condenser fan motor is what blows air across the condenser coil. If it overheats, it could trip the breaker. The following are a few causes as to why the condenser fan motor overheats.

  1. The homeowner or A/C technician installed the wrong sized motor.
  2. The homeowner or A/C technician installed the wrong start run capacitor or an incorrectly sized fan blade.
  3. Poor airflow. Fan blades not installed in a correct position can result in a lack of airflow and cause the motor to overheat.

Furnace Filter - No Air Flow

Dirty or clogged furnace filters reduce airflow, making a furnace or air conditioner work harder to circulate hot or cold air. In some cases, an obstructed filter may break the limit switch, which controls the fan. Normal wear and tear can cause airflow difficulties, heat control-related problems, or even the furnace overheating. Filters should be changed a minimum of two times per year, spring when you first turn on your a/c unit and fall when you first use your furnace. Change the filter four times a year. If you have a cat or dog(s).

alt= "Clogged air filter which is the primary cause of air conditioner problems. the pro's at TNT Heating and Cooling located in South Lyon, Mi."

Malfunctioning Capacitor.

The capacitor is a small, inexpensive part that regulates the electrical flow for the fan, motor, and compressor.  The following are clues it might be a bad capacitor:

  1. Humming Noise
  2. Air conditioner Turns Off on Its Own before reaching the desired temperature
  3. Air Conditioner Doesn’t Turn on Immediately or won’t turn on at all


Central heating and a/c systems are controlled by a low-voltage thermostat (operate with a transformer that reduces 120 volts to 12 or 24 volts) that tells your furnace or a/c unit when to turn on and off when the temperature has reached the desired temperature.

Three air conditioner symptoms are often attributed to problems with the thermostat: Produces no cooled air; the air conditioner exceeds the desired temperature by making it too cold, or the air conditioner turns off and on repeatedly “cycles.”

alt= "Severe refrigerant leak on outdoor condenser unit serviced by the pro's at TNT Heating and Cooling located in South Lyon, Mi."

Refrigerant Leaks

Air conditioners use refrigerant to remove your home’s warm air. Refrigerant travels through closed copper coils cooling the air that passes over them. Sometimes the coils crack from vibration, or one of the many joints or connectors fail and leak refrigerant. If you notice ice on any part of the refrigerant lines, a hissing noise or a sweet chloroform odor, then you have a leak.  A qualified a/c technician should be called to repair it. Charging your system is not a do-it-yourself project.

Air Conditioner Drainage Line

When working correctly, the drain line helps eliminate condensation that builds up within your a/c unit. The moisture is disposed of through the drain line to in most instances the outside of your home. The a/c drain line can become jammed with dirt or debris causing the water to back up into your system and keep it from working.

How to remove a small or large clog

First, make sure your inside thermostat is set to off, then find the cleaning port on the drain line. You may want a small bucket handy. Remove port and visually inspect for a clog. If you can remove it without further pushing it farther away, then try that first. If you can’t see the clog, carefully pour a solution of hot water and dish soap in a large measuring cup into the port, filling it to the top. If the solution drains slow, you probably have a significant clog so continue poring solution until it flows freely. If the obstruction is still there after several attempts, then call an HVAC Technician.

alt= "A clogged air conditioner drain line serviced by the pro's at TNT Heating and Cooling located in South Lyon, Mi."

Proudly serving residents of Brighton, Canton, New Hudson, Northville, Novi, Plymouth, South Lyon, and Wixom, Michigan

Leave a Comment

Your email address will not be published. Required fields are marked *


Call Now ButtonCall TNT Heat & Cooling