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How to get car's A/C blowing cold again

  • Story Highlights
  • Warm car air temperature could be due to a faulty refrigerant system
  • Low air volume could be due to a faulty air duct system
  • Leaks from ruptured hoses or poor connections result in system shutdown
  • There are two refrigerant chemicals used for automotive air conditioning
By Tom Torbjornsen
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(AOL Autos) -- Car expert Tom Torbjornsen answers a letter from a auto owner:

Dear Tom,
I own a 2006 Chevy Silverado 1500 pickup with a 5.3-liter V8 engine. My air conditioner is weak. Do I need to recharge it? Should I take it to the dealer or can I go to an independent repair shop? If it's expensive, how long can I go without repairing it? -- Shannon from Lubbock, Texas

Shannon, when you say "weak" do you mean warm air temperature or low air volume? The answer to this question will determine the correct diagnostic pathway.

Low air volume could be due to a faulty air duct system; warm air temperature could be due to a faulty refrigerant system in the A/C. If a refrigerant leak is found then the system will need to be recharged.

However, if the problem is due to a malfunctioning duct then recharging won't be necessary. If your truck is still under the 3-year, 36,000-mile warranty, then I would take it to the dealer because it might be covered under warranty. Otherwise, you can take it to whomever you want.

Don't leave an A/C system unattended because it will cost you more money down the road.

This time of year I get a lot of questions about air conditioning repair. First of all, when describing your air conditioning problem, make sure to tell the tech exactly what is happening. Is the air too warm? Or is the air cold enough but low in volume?

Warm air could be caused by a refrigerant leak, system blockage, or a faulty component such as a compressor. (The compressor is a pump that pumps the refrigerant chemical through the system.) Low air volume means that the air stream being fed into the vehicle cabin is impeded by something, such as a faulty air duct door or clogged air vent.

Here are some common questions I get about air conditioning

Do I need to recharge the A/C? If your air conditioner needs recharging it is because the refrigerant chemical is leaking out of the system. Many people think that air conditioners naturally leak refrigerant, so they assume they have to take the car in every year for recharging. This is not true.

The refrigerant is not supposed to leak. If the refrigerant is low, find and repair the leak. There should be no reason for a recharge. Should I take it to the dealer or can I go to an independent repair shop? If the vehicle is still under the factory warranty, then go to the dealer so the repair is covered under warranty. If out of warranty, go to whatever qualified shop you desire. AOL Autos: How to choose an auto repair shop

How long can I go without repairing it? What will happen? Here's my answer to this very familiar question: A/C systems fail when any of the following things happen:

Refrigerant leaks -- Leaks from ruptured hoses or poor connections result in system shutdown. Loss of refrigerant oil due to a leak can cause compressor failure.

Dirt -- Anything other than refrigerant chemical and oil in an air conditioning system is considered dirt. Dirt can cause seized compressor bearings, expansion valve failure, decomposition of refrigerant and oil, and corrosion of metal parts. AOL Autos: Do I need to replace my air filters?

Restrictions -- These can happen for a number of reasons. The most frequent? Dirt, metal shavings, powered desiccant (moisture absorbing material), and foreign matter from the atmosphere. These substances cause high pressure, heat buildup, and loss of lubrication within the A/C system. The deadly duo (pressure, heat) cause "O" ring decomposition, brittle A/C hoses, and seized compressor bearings. Loss of lubrication can result in compressor failure. AOL Autos: Be smart and spring clean your car

Moisture -- Combined with metal and refrigerant, moisture can cause the formation of oxides and acids, a sure death sentence to any A/C system. Additionally, moisture can freeze up expansion valves and powered desiccants. All these items cause A/C system failure.

How long can you go with an inoperative system before A/C failure? As long as it takes for these conditions to set in and cause failure, and it isn't long. AOL Autos: How often should I change my oil?

How do I know if my car uses R12 (Freon) or R134A? There are two refrigerant chemicals typically used for automotive air conditioning: R12 (or Freon), and R134A. If the system uses R134A the input taps will be clearly tagged as such.

Does the air conditioner work the same as the heater, only in reverse? The heater in your car is nothing more than a small radiator. Hot water passes through what is called the heater core. Heat emanates off the core and this hot air blow into the car to heat the cabin.

The air conditioner operates much differently. The A/C system uses an evaporator core. The refrigerant chemical is pumped through the core (which is much like a small radiator or heater core). The evaporator carries the refrigerant chemical into the car where an interesting exchange takes place ... cold air is exchanged for the hot air in the car. AOL Autos: Can your car last 1 million miles?

The refrigerant chemical saps the hot air out of the car by absorption and exchanges it for cold air. The cold air that is radiated from the evaporator is blown into the car's ventilation system, cooling you down. Dehumidification also takes place during the process.

Have you have ever wondered where all that water comes from under your car? It comes from the dehumidification process while the A/C is running.

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