How to check your air conditioning

Posted on June 30th, 2020 by Rob Marshall

How to check your air conditioning

Due to its dehumidifying benefits of clearing misted windows efficiently, GEM recommends the all-year-round use of air conditioning. Yet, using the ‘air-con’ regularly also has a technical benefit, a primary reason of which is that the refrigerant is less prone to escaping. If it does so, the system stops working.


We do not recommend DIY refrigerant top-ups. Not only can they be a false economy but you may also cause damage. One reason is that you risk overfilling the system. Another issue is that you cannot be certain that there is a major leak, resulting in harmful gas simply being vented into the atmosphere illegally.


While we recommend that all air conditioning repairs to the refrigerant side of the system are addressed by a suitable professional garage, there are checks that a typical car owner can make. With the air conditioning activated and the engine running, you can check the following:


In many cases, you may hear a dull ‘click’ coming from the engine bay, as the air conditioning compressor switches-on. This tends to be accompanied by the engine cooling fans starting to run and a slightly elevated engine idle-speed. These symptoms indicate that there is sufficient refrigerant remaining to activate the air conditioning system.


1. Check that the air temperature coming from the vents is lower than that externally. Sometimes, you can simply feel this with your hand. Otherwise, use a digital thermometer to provide an accurate measurement.


2. If you are a keen DIYer and the compressor is not being activated, you can interrogate the system through the On Board Diagnostic port. A fault code reader may not help you; use a tool that is sophisticated enough to extract live data that will allow you to make an informed diagnosis.


3. With the engine switched off and cold, preferably with the battery 4disconnected, remove deposits from the air conditioning condenser, which sits ahead of the car’s main radiator. If clogged with dead leaves and other deposits, this will affect the air conditioning’s effectiveness. Take the aforementioned precautions to prevent the engine cooling fan(s) activating.


5. Part of the air conditioning system, the evaporator, is located behind the dashboard. It chills warm air that passes over it. Yet, it becomes damp and bacteria builds on its surfaces, the spores from which are then blown into the cabin through the air vents. These can affect your lungs, especially if you are asthmatic. Therefore, use an anti-bacterial aerosol ‘bomb’ to clean it- more details about which are in an earlier GEM blog <>.


6. Ensure that the cabin filter is renewed once a year.


7. Check that the belt that drives the compressor is not frayed and is replaced every time the timing belt kit is replaced, or every 80,000 miles at least.


In a following blog, we shall look at how professionals deal with air conditioning repairs and for which procedures you should expect to be quoted.