My air conditioning unit isn’t cooling. What’s wrong with it?

Poor performance could be due to one or more factors:

Low refrigerant:- An air conditioning system requires a minimum amount of refrigerant to cool properly. If the refrigerant level is low, it will work less efficiently and will not cool well.

Dirty condenser:- The condenser is the heat exchanger which cools the hot high pressure refrigerant after it exits the compressor so that it can condense into a liquid. If the condenser is full of leaves, insects or other road debris, air flow through the unit may be impeded to the point where little cooling can take place. Cleaning the condenser should cure this problem.

Condenser cooling fan not working:- The condenser often has its own separate electric cooling fan. This fan should come on, and remain on, when the air conditioning system is operating. If the wiring, fan motor, or motor relay is defective, the fan may not work.

Internal blockages:- Any type of debris, e.g. rust, in the system may block the tube or the metering valve through which refrigerant flows into the evaporator. This will cause a loss of cooling, and potentially cause damage to the compressor as the system probably relies on oil circulating with the refrigerant for lubrication.

Air or moisture contamination:- The refrigerant inside the system, which must remain free of moisture, can freeze and form ice that will cause blockages. Contamination can result from leaks in the system, or failure to vacuum purge the system prior to recharging it with refrigerant.

Other electrical or mechanical problems:- These would include compressor wear, the compressor clutch failing to engage, metering valve failures, inoperative pressure switches, etc. Precise diagnosis will require a technician who has all the necessary tools and equipment, and who has been trained in this highly specialised process.