Vehicles AC Not Working

Vehicles AC System Not Working?


How To Diagnose Your Car’s AC Problems

There is nothing worse than having your vehicle’s air conditioning system go out, especially in the middle of summer. Long, hot car rides can easily ruin your day, and drives to and from work can be unbearable. 

Here are a few steps you can take to diagnose your vehicle’s AC problems in order to get your air conditioning system back to a pleasant, working condition.


First Things First – Safety

Always wear safety gloves and glasses when working with vehicle liquids and refrigerants. Refrigerants can freeze the skin quickly and become very painful. If you happen to get refrigerant on your skin or in your eyes, immediately flush with water and get medical attention as soon as possible. 

Vehicle Air Conditioning Overview

Your automobile’s AC system cools the inside of your vehicle by a cycle process that removes heat. Diagnosing your vehicles AC issues can be complicated even though there aren’t many moving parts in the AC conversion process. Many other components can cause warm air to filter through the vents. Here are some common causes for AC issues and why your system may be blowing hot air.


Refrigerant Leaks


The most common problem with under-performing AC systems in vehicles are low refrigerant levels due to a leaky O-ring seal or other component leaks. A small amount of refrigerant loss can affect the chill level from your vehicle vents. Short-cycling, or the AC compressor clicking on and off, is a very good way to tell that you might have a leak or low refrigerant. 

Here are some steps to take if you suspect a leak:

  • The easiest way to find a leak is to use a UV AC Leak Detection Kit.
  • Check the hose chambers on the compressor, as well as inspect where hoses are crimped into fittings
  • Inspect front seals and o-rings
  • Check around all fittings to verify that they are all secure.
  • Check the Schrader Valves.
  • Look for small holes in the condenser.
  • Check where the evaporator drains condensation. 

Recharging your vehicle’s AC system is usually a one-time fix. Be sure to visit your local repair shop if your system needs recharging.


Is Your AC cool but not cold?

Turn your vehicle’s AC system on “Max AC” and set your fans to high. If your vents are only pumping out medium to slightly cool air, there is probably an issue.

  • Inspect the cabin air filter and make sure it is not clogged.
  • Check for any clogs or restrictive debris that would keep air from passing over the condenser.
  • Is the cooling fan or radiator running when the vehicles AC system is on? If not, there may be a problem with the cooling fans or radiator systems.

If none of these seem to be an issue, the next step is to check the pressure systems. This can be done using a manifold gauge kit. 


The AC Compressor

The easiest place to begin your inspection for an AC systems issue is to begin at the compressor. The compressor is a very common cause associated with vehicle AC issues. A good spot to start is by checking the clutch assembly at the front end of the AC compressor and make sure it is engaging.

The AC compressor is a pump that cycles refrigerant throughout the system. Here are some steps to check for common problems with the compressor: 

  • Turn on the engine and set the A/C system to max cool. Put your fans on high, then listen or inspect to make sure the clutch on the compressor is engaging. 
  • If the clutch does not engage and the system appears to have refrigerant, check your voltage getting to the compressor by using a voltmeter
  • If there is voltage, you may have a clutch issue. 

Leaks in seals of the compressor are a very common occurrence. Debris inside the compressor is also a common issue. A failing AC clutch can also be a cause of compressor issues.


AC Orifice Tube |  Expansion Valve

Most modern AC systems use an expansion valve or orifice tube to regulate the amount of refrigerant that enters the evaporator. 

Common problems with accumulators and driers include: 

  • Moisture and particle contamination that clogs the tube screen or expansion valve. 
  • Incorrect refrigerant levels
  • Condensor fans are not working properly. 

AC system pressure tests can determine if there is an issue with the expansion valve or orifice tube.


AC Evaporator Core 

If there is hardly and air coming from the vents, but you still notice the blower fan running, the evaporator core is probably clogged. Additionally, if you notice an unusual smell when using the AC, you probably have a leak in the evaporator. 

The evaporator core is a very hard issue to find and fix. This component acts like a large ice cube with small holes. It is was cools the air when cabin air flows through it. 

Common problems with accumulators and driers include: 

  • Evaporator leak (caused by age or wear and tear)
  • Clogged evaporator core


AC Accumulator/Receiver Drier

The Accumulator/Drier collects and absorbs moisture. They use desiccant to absorb moisture in the AC system which can build up in a system that is low on refrigerant or has leaks.. 

Common problems with accumulators and driers include: 

  • Desiccant material entering the AC system causing internal failure. 
  • Compressor damage due to leaks that result in over-saturation of the desiccant material.


AC Condensor

The AC Condesor works with the radiator fans. Air flow over the condenser tubes cool the hot refrigerant and returns the refrigerant back to a liquid state. 

Common problems with accumulators and driers include: 

  • Refrigerant leaks
  • Contamination from the compressor or accumulator is blocking the flow of refrigerant. 
  • Condensor fans are not working properly. 

Rattling or banging from the compressor, or noticing the drive belt slipping, are issues that can cause excessive AC pressure.


Electrical Issues

On newer model vehicles, electrical issues may be the culprit for an improperly working AC system in your vehicle. 

Any number of fuses can cause issues with your blowers, fans and relays with can effect the cooling performance of your vehicle’s AC system. Additionally, be sure to check the ECM (engine control module) which can affect the AC system. 

These issues can often be easily addressed and fixed by using a voltmeter or test light. 




Fixes and Prevention

If you are unfamiliar with vehicle repair, it is highly recommended to have a certified technician perform the proper services to fix your vehicle’s AC issues. DIY repairs should only be performed by those with knowledge of vehicles and vehicle repair. 

Running the AC system in the winter is a good way to help prevent issues as it circulates the refrigerant oil and lubricates your seals so the system is ready come the hot summer months. 



Leave a Comment

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