New & Rebuilt Auto Air Conditioning Components

How many ways are there to check for leaks?

Checking for leaks is always a problem. A system needing service almost always has a leak. The problem is, how long did it take to leak down? It could be a year, six months, or a week. Time helps to determine the size of the leak and where the leak is. This is information that no one has.

Oil in the system travels with the refrigerant, so if a leak is to be found, it is important that the unit is not operated before a leak check is made. The worst leak can seal itself with oil for a period of time, making it impossible to find.

Dyes used in the system to locate leaks have been around long enough now that most systems have some dye in them. All the tools at your disposal must be used to locate leaks. Dye can be detected with a black light, visual inspection, pulling, bending and twisting hoses and their connections, soapy water, or with an electronic leak detector. One of these techniques will generally find the leak. An oily hose is a good indicator that it is leaking. There should be no oil on anything else but the hose. Try to bend the hose and see if it cracks and pops when bent. If so, that is an indicator the inside of the hose has become brittle. This can cause the compressor to fail if it is the suction hose.

Systems have blow-off valves that are set to release pressure around 440lbs. If the fans on the radiator do not function, dirt on or trash in front of the condenser stops airflow, causing this valve to blow. Anything that could cause the pressure to rise in the system could also cause the valve to blow. Most of these valves are located in the compressor; however, some are located in the manifold assembly.Some manufacturers place a piece of tape over the valve. If the valve blows, it blows the tape off.  

What Causes a compressor to fail?

A compressor that supplies air for an automotive service center runs every day and several times a day, and they last for years. If the compressor on a car can last from 60,000 miles it is considered old.

"But Why?" You ask.

In reality a shop compressor and an A/C compressor are not that much different. The major difference is that the automobile under hood temperatures can reach 400 degrees. The car's compressor relies on returning oil to the compressor for lubrication. The car's condenser has to remove heat so the compressor will operate cooler allowing the system to function. When these elements get out of their operating ranges, the compressor has to work harder and it operates hotter. These conditions are more damaging to the compressor.

A compressor that is running too hot can be caused by one or more of the following;

  • Excessive high side pressure because of too much refrigerant, contamination of the refrigerant, dirty condenser, restricted condenser, and too much or too little oil.
  • A compressor that runs hot will cause the seals to become damaged and start leaking.
  • A system that has too much oil will allow oil to accumulate in the back of the compressor when at rest and then try to compress it when the system is turned on.
  • Cooling systems that run hotter than normal, but not considered to be running hot, can cause the compressor to run too hot.
  • Not enough oil will result in the compressor running dry of oil. This will cause excessive friction in the compressor and its eventual failure.
  • Mixing of synthetic oils and mineral oils must not be done. The correct viscosity of oil for each manufacturer must be used.
  • Last, but not least, is how the A/C unit is turned on and off. The best way to use and A/C system is to turn it on and never turn it off.

Austin Rebuilders, Inc.
505 West Oltorf Street * Austin, TX 78704

512-448-0884 * 512-448-0218
512-441-2780 Fax

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