For proper Air Conditioner Troubleshooting you need to understand some basics of air conditioners. This includes basic refrigeration, electricity, electrical components and how electro-mechanical controls work. In addition, basic air conditioner components and air conditioner sequence of operation. Before troubleshooting you need to identify the basic problem with the system.

Is it a component not working and why is the component not working? In addition, having the proper tools along with knowledge will also help you in troubleshooting air conditioners and fixing problems.

For example, is the compressor working and if the compressor is not working is it the compressor that is bad. Or could it an electro-mechanical component that controls the compressor and motor that is the problem? So in the process of air conditioner troubleshooting you need to know the basics of air conditioners. You also need to understand basic techniques for troubleshooting different electrical and mechanical aspects of the system as a whole.

Air Conditioner Troubleshooting | HVAC Technical

Airconditioner problem repair
Air Conditioner Troubleshooting HVAC CondensersRecapping Essential Knowledge:

  • Refrigeration Knowledge
  • Electricity Knowledge
  • Electrical Components and How these Components Works
  • Air Conditioner Sequence of Operation

Types of Airconditioners

There are two basic types of central air conditioners. The package system where all the components are in one unit or package. There is the split system central air conditioner. These systems will have the components split from each other and connected via wiring and a refrigeration line set.

Both systems have basically the same components but these components have different configurations. Finding the problem will require understanding these basic components and controls. Whether they are configured in a split system or a package unit system.

Components - The Evaporator and Possible Evaporator Problems

AC Repair with evaporator problems

This evaporator coil got limited airflow from old insulation

The Evaporator coil is a one of the major components. And depending on the problem that needs repair depends on whether to check the evaporator coil in the air conditioner. The evaporator coil receives low-pressure low-temperature refrigerant.

As the refrigerant passes through the evaporator coils it absorbs heat from the air that passes over the coils. When troubleshooting you need to check that the coil has the proper amount of air flow across the coils. Airflow first and then refrigerant charge next.

It is also important the proper amount of refrigerant is available inside the evaporator coils. The air conditioner system can be overcharged and too much refrigerant in the system.

The air conditioner system can be undercharged (possible refrigerant leak) and not have enough refrigerant. Therefore, you need tools and knowledge of these things to check the charge. Finally, remember, air flow first and then refrigerant charge.

Skills for Fixing the Air Conditioner Problem

You need to have the skills and the tools to know the proper charge. With airflow across the evaporator coil in air conditioner troubleshooting you need to check the filter to make sure it is not clogged with dirt or debris. Make sure the blower is turning the proper RPM’s and providing proper air flow. It needs to pull (or push) the proper amount of airflow across the evaporator coil.

Too many supply vents closed off can cause air flow problems, therefore creating the issue. It is important that evaporator coil has the proper amount of airflow across the coil to ensure the air conditioner is working properly. In finding problems with air-conditioners, this is an essential check of the air conditioner system. Make sure the airflow is good across the evaporator coil when looking for air conditioner problems.

Air Flow, Air Flow and Air Flow

Any air conditioner relies on proper air flow. The common sense approach for troubleshooting the air conditioner is to check the air flow. Clogged air filters and collapsed duct work, bad fan motor, and other such problems as described above. These are common things to check before pursuing further issues and wasting your time!

Recap Evaporator Coil Issues:

  • Always make sure you have the proper air flow
  • Check the filters and fan, duct work and closed supply vents for restrictions of air flow

The Condenser and Possible Condenser Problems

bent fins on condenser coils

Bent Fins on Coil cause air conditioner problems

The condenser coil receives high pressure high temperature refrigerant from the compressor. The compressor and the condenser can be integral to the condensing unit in a split system.

The compressor and the condenser coil are important components in any type air conditioner system. The refrigerant gas travels from the evaporator coil to the compressor. There is a change from low-temperature low-pressure refrigerant gas to high-pressure high-temperature gas.

Proper training and tools are required to check or troubleshoot the compressor. A basic practice for a compressor is to check the wiring. When checking any electrical components in any type of machinery or mechanical equipment turn off the power and double check it is not powered.

Related Link: Air Conditioner Circuit Board Troubleshooting - Delve Deeper and Learn more about HVAC.

Furthermore, when an air conditioner fails the wires on the compressor are be burned off, therefore causing the problem. Loose electrical connections or corrosion cause compressor failure. Corrosion can cause a loose connection. All electrical connections at the compressor need to be tight. These connections also need to be free of corrosion. When you see what you are dealing with you will understand proper training and tools are a necessity.

Air Flow in the Condenser

compressor problemsHermetically sealed compressors are normal in residential condensers and light commercial systems. Therefore, it is difficult to check the internal components of the compressor. The compressor and the condenser coil in air conditioner troubleshooting the condenser coils need the proper amount of airflow.

You need to check the condenser coils for dirt and debris. Remember to turn the power off to the unit before washing the coils. The compressor and the condenser coils work together. The compressor sends the coils hot gas and the coils remove the heat from that gas. The condenser and the compressor work together to make the air conditioner function properly.

You should check the condenser air flow. You need to make sure the condenser fan motor is working properly and turning at the proper RPM’s. Designed air flow is important for the condenser coils. If the condenser fan motor is not working at all the AC will not function properly. Therefore, it is possible could cause severe problems and damage the system.

The compressor relies on the fan motor for air flow and without air flow pressures rise. If the fan motor is not working, then it could be a bad motor. A bad capacitor or a bad relay or compressor contactor that controls the fan motor and compressor. Proper knowledge of electro-mechanical controls and electric motor basics will help. It will help you understand the problem much quicker when making repairs to AC’s.

Condenser - Essential Component

The condenser is an essential component and if the condenser has problems the air conditioner will not function properly. The condenser is most likely the component where you will find problems.

The condenser is where you will troubleshoot problems with electrical, refrigeration, and some other basic problems. Things like clogged fins in the coils of the air conditioner. Be careful as condensing units and other major components of the air conditioner utilize high voltage that can kill.

Recap for Condensers and Condenser Components:

  1. Be careful!! Doing a thorough check of the electrical system and components in the condenser is necessary. Caution!!! High Voltage!! Only a properly trained technician should perform these checks and do so carefully.
  2. A compressor check and a check of the refrigeration system.
  3. Basic knowledge of refrigeration and refrigeration components is necessary to determine the proper refrigerant charge.
  4. Compressors and condenser coils work together.
  5. Compressors and condensers problems can effect one or the other component and need to fixed.
  6. There are two types of air conditioner systems: The split systems and the package unit.

Controls and Control Problems – Air Conditioner Troubleshooting

circuit board problems cooling

Circuit Board for an Air Conditioner

Compressor Contactor is an HVAC Control. When seeking problems with air conditioning systems you need to understand basic air conditioning controls.

Controls include the thermostat to any relays or contactors in the air conditioner system. Thorough knowledge and understanding of these components and devices will make the process easier for the technician. It is also a good thing to understand other HVAC circuit basics such as Ohms Law.

These basic circuit principles help you understand electric problems easier. Many modern air conditioning systems use printed circuit boards for control. Some components, however, are still contactors and relays. These components control fan motors and the compressor in the air conditioner system.

Technicians can find problems with the air conditioning control circuit board easily. A circuit board can appear to be confounding to the vast majority. After all, it is a control circuit board. There are rules to follow in troubleshooting a basic HVAC circuits. One is that the circuit board needs a source of power and the source typically comes from the transformer.

When powered it will have a sequence of operation and an order of operations. This is based on input from the thermostat and any safety circuits in the air conditioner system.

You check the input voltage and based on the sequence of operation you check the output. Input is important and mandatory for proper function of the circuit. If no input, then you need to check the source and fix that before proceeding.

If you have input to the board and no output, then you need to check why there is no output. The problem is in the board and needs to be looked at carefully.

Control Voltage and Control Circuits – Air Conditioner Troubleshooting

Maybe there is a problem with the circuit board or the safety circuit is open somewhere. That will prevent the output from occurring and the unit from operating. With relays and contactors in air conditioner troubleshooting, you need to understand that something is controlling the relay or contactor. The relay or contactor has a function to either open or close. This is based on the control voltage and where the control voltage originates.

The origin of the control voltage in most residential HVAC systems originates from the step-down transformer. You will find the transformer in the equipment somewhere. It is important to understand the step-down transformer and how it works.

As with the circuit board above. If you have input but no output, therefore something is wrong with the component. In this case, it is a control step-down transformer. Does the HVAC system have one or two transformers? Air Conditioner troubleshooting requires one to know these answers and how to answer the questions and solve the problem.

Almost all relays and contactors in a typical air conditioner system are controlled by the thermostat. When the thermostat calls for air conditioning it closes some contacts in the thermostat. This completes the circuit for the control voltage.

That process sends control voltage to either a relay or a contactor or both. When the relay or contactor or both close the contacts inside the relay or contactor close. This completes another circuit which is typically line voltage but can be a control circuit. This line voltage energizes compressors and fan motors and the system starts. And the control voltage controls many other components including relays and contactors.

Reading Ladder Logic Diagrams

As a result of learning ladder logic you will understand the sequence of operation. The sequence as designed by the engineer and the manufacturer. This makes the air conditioning problem-solving process becomes simpler because of that understanding.

That is if the air conditioner comes with a ladder logic diagram. Many air conditioners do not come with a ladder logic diagram but most noteworthy, a component pictorial diagram. A good technician can take a pictorial diagram and draw their own ladder logic diagram. In doing that you can better understand sequence of operation for the air conditioner system.

Air Conditioner Troubleshooting Conclusion

Finally, the bottom line to finding and fixing air conditioner problems is to understand the basic components of the system. Then break the system down into parts and look for problems. When seeking problems with air conditioning a good technician can easily and quickly identify problems. They quickly identify the part of the system which is causing the failure and make appropriate repairs to the system. Much of this comes from learning the air conditioning system basic knowledge and part of it comes from field experience. Taking a course in HVAC and AC controls and refrigeration will help you, therefore you need to study. It will help you understand these processes and make you more efficient at repairing air conditioners.

Other resources can be found here.

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Air Conditioner Troubleshooting | HVAC Technical

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