Not cooling: The first warning sign is the most obvious: there is simply no AC. If you’re getting a whole lot of nothing out of the vents or warm or hot air instead, you could have a problem with your HVAC
system. This could be happening for a number of reasons: you may be
out of refrigerant; you could have damaged cooling fans; or even
something simpler, like vents or a cabin air filter clogged with leaves
or other debris.
Slow to cool: Does it take longer than usual for the interior of your car to cool down? If it does, there may be an insufficient amount of
refrigerant in your car’s air conditioning system due to leaks. If the
problem is not addressed immediately, it could put a lot of strain on
your car A/C system.
Strange sounds: The next easiest AC warning sign to spot is weird
noises coming from the system. If you turn on your air conditioning
and start to hear a hissing sound it may be low on gas, if you hear
banging, rattling or worse, it may be leaves or debris clogging up your fan Or a part of the air conditioning system itself could be worn out
and about to break.
Preventative maintenance: keeping your air conditioning regularly serviced helps prevent wear and strain on the system, when the air
conditioning system is serviced moisture is removed from the internal
parts of the system preventing corrosion, system is leak tested, any
lost oil is replaced and the system is filled with new gas, performance
is checked and your system will now work efficiently.