Thursday, April 15, 2021 Detailed Auto Topics
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There are two things most people know about automotive air conditioning. You cannot do without it [in South Louisiana] and it is expensive to repair. The first is a fact the second can often be prevented.

Many of the large repairs we see on automobile air conditioning, include compressor failures. When a vehicles compressor fails there is a cause. Very often the cause is rooted in improper previous service and ignoring the warning signs. By recognizing the warnings, vehicle compressor failure can be greatly reduced.

There can be dozens of reasons for an automobile air conditioner to stop cooling. One of those reasons is a leak. The refrigerant leaks out and the car stops cooling. The old method of "adding some Freon" will not work, it can quickly do considerable damage.

Damage can be done by improper charging of air conditioning 

A leak and low charge is one reason for the unit to stop cooling. It is by no means the only. An electronic condenser fan turning too slowly can very quickly increase compressor pressure to a dangerous level. Most automotive systems will shut down and stop cooling. Adding more refrigerant to such a system will destroy the compressor. The original problem was a fan repair.

Modern vehicle systems are very small, compared to just a few years ago. Up to 80 ounces of refrigerant was used in older systems. Today many systems operate on less than 12 ounces. Adding 12 ounces to an 80 ounce system resulted in a 15% overcharge. Adding the same 12 ounces to a 12 ounce system results in a 100% over charge and damage.

Making the situation far more complex is the wide usage of variable displacement and computer-controlled compressors. These units vary their pressures constantly and reading a set of gauges will not produce the right charge. A unit can be seriously over or under charged and not indicate it on refrigeration gauges.

To properly charge such a system, it must be fully evacuated and the precise amount specified added. This requires a recycle machine to extract the old charge, a charging cylinder and a precise digital scale.

If the system is actually low, repair can still be fairly straight forward and inexpensive. The leak must be found, corrected and the system properly recharged. Many times this may involve replacing a switch, hose, O-ring or an evaporator core. Properly diagnosed and repaired, the leak will cause no further problem. Ignoring the leak and adding refrigerant will often add the price of a compressor to the job.

Preventing compressor failure involves a quick response to the warning signs:

  • The air conditioner does not cool as well as before

  • The vehicle warms up when sitting and idling

  • The system warms up after driving a distance

  • There is a noise when the system is turned on or off

  • The air conditioner stops cooling

  • Water is dripping inside the vehicle

Bringing the vehicle to a professional like AGCO at the first symptom can often save hundreds of dollars in unnecessary repair. AGCO, it’s the place to go.



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