A/C Faulty? Could It Be a Relay or a Bigger Problem?
Posted on: 20 April 2020
If your car is blowing warm air into your face when you try to activate the air conditioning system and the weather outside is truly frightful, you will want to fix the issue as soon as possible. You may worry about an expensive repair bill, but it could be something relatively small. As always in a case like this, begin with the simplest component and work along from there, but where should you start?
Simple Solution
As the fan is blowing warm air, this suggests that the compressor is inactive and the fan is simply overriding the main part of the system. The issue could be associated with a faulty relay, and this could be down to a simple failure or the sign of a larger problem elsewhere.
Simple Failure or Something Else?
As you may know, a relay is essentially a switch that is designed to activate a more powerful auto electrics component on a selective basis. It will receive a signal from the ECM when you attempt to turn the A/C on which will, in turn, open a magnetic field and complete the circuit. There are many different relays in your car, and they are all relatively cheap parts. In this case, the relay may have failed, and the simplest way to find out is to replace it with a brand-new relay.
Low Refrigerant Levels
However, the relay may be perfectly fine, but a separate sensor may have deactivated it due to a problem elsewhere in the system. Most vehicles these days have pressure sensors that are situated throughout the A/C system and designed to check whether the pressure is acceptable. If it isn't, this might mean that the refrigerant level is very low and will need to be addressed as soon as possible. In this scenario, the pressure sensor will override the message from the ECM and prevent the relay from tripping the compressor.
Time for a Service?
When was the last time that you serviced the air conditioning system? If it has been a long time, then the refrigerant may be critically low, or you may have developed a leak around one of the seals or pipes.
What to Do Next
Take the vehicle in to a mechanic so that they can service the entire air conditioning system. If there is a faulty relay then they will be able to change that easily but crucially, they will be able to refresh the refrigerant levels so that you don't run into any other problems.
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