How To Repair Mercedes Air Vent

How Air Conditioning Units Are Repaired

Last Updated March 25, 2020

Air conditioning isn't a luxury when you're driving in a car in 90-degree heat. When a person overheats they can lose focus, have a shorter temper and make mistakes. Luckily, it's possible to fix a broken AC unit. There are three main parts to the air conditioning unit – the compressor, the condenser, and the evaporator. The fault could lie with any of those parts or it could be that the unit needs recharging. First, make a visual inspection of the unit to see if there are any obvious signs of damage.

Symptoms

The obvious symptom that something's wrong with the air conditioning unit is that it doesn't run cold enough but there are other less obvious signs that suggest a problem with the unit including loud noises when the compressor is running or the AC clutch not moving. The fault could be something as simple as a blown fuse, an opening in the wire to the clutch coil, a faulty clutch coil, a low-pressure lockout or something more complicated to correct.

If you're going to get this checked out by specialist mechanics, tell them the symptoms you've noticed which will give them a clue to the problem but they'll normally carry out a visual inspection of the air conditioner's compressor drive belt, it's serpentine belt and any other accessible components for damage, cracks and leaks. Replacing one of these parts is the quickest and cheapest way of repairing the fault but if the issue's not obvious, the engineers will need to check how well the air conditioning compressor is operating.

Air Conditioning Compressor

If no leaks are found during the engineer's visual inspection, dry nitrogen will be used as a pressure test to make sure there are definitely no leaks in the system. A vacuum pump is then used to remove any moisture and static air from the system. Once that's done, a refrigerant source is attached, which can be bought from your normal car parts retailer or the internet. Make sure the engineer's using the refrigerant appropriate for your car as set out in the vehicle's handbook or listed on the manufacturer's website.

While It's Charging

While the system's being recharged, start the engine and turn the air conditioning on. Put it at its highest setting and use the fastest fan speed as this will work the system to its maximum which will charge the system fully. Once the engine's running and the system is switched, the refrigerant enters the system and you'll begin to see the pressure gauges increase from low to high pressure. Your engineer will have to be careful not to overfill the refrigerant as this can lock up the compressor, although in some cars the compressor shuts off automatically when the system's overcharged.

Regular Maintenance

Spotting small problems before they become big headaches for you is the key with your air conditioning but you can prevent problems by running the system once a week for at least ten minutes to maintain gas pressure and to keep the compressor running properly. Run the defrost mode for at least five minutes too. This means that you'll need to use the air conditioning in all weathers and all seasons, including winter. Making sure that the system is recharged when it needs to be and getting it regularly serviced are the other ways you'll keep it working.