from Goss’ Garage by Pat Goss

Your car’s air conditioner is busted, it’s ninety degrees, traffic is crawling, you’re sweaty, your clothes are wet and sticky and you stink; it really sucks. Sitting there sweating your ass off you probably don’t care that the most common air conditioner problem is refrigerant loss but it is. Refrigerant is what it is but Freon® is what most folks call it, which is wrong because Freon® is actually a DuPont trade name for a specific type of refrigerant. But no matter what you call it refrigerant leaks causing cold air to become cool air and cool air to become hot air! Myth exposed: No matter how many bizarre theories you hear the only possible way for refrigerant to leave an AC system; is through a leak! Refrigerant gone, system has a leak.

Warning: Never try to top off your system with a kit from the auto parts store. Without proper test equipment you can’t know how much refrigerant to add and adding too much can do serious damage. Grim Warning: Absolutely never add stop leak.

Although refrigerant loss is common and is one of the first things to check there are lots of others. Finding the actual problem requires a systematic diagnosis using an AC refrigerant identifier, pressure gauges and a written diagnostic procedure. Note: Because it’s rarely done, insist that your technician use a temperature and humidity compensation chart to adjust pressure readings or the diagnosis could be totally, expensively wrong. Another mistake is not using a refrigerant identifier which could save hours of diagnostic time. In five minutes or less the identifier lets the technician know if there is improper or contaminated refrigerant and even if there is air in the system. Today, a refrigerant identifier is a must have, must use tool.

If the compensated readings are correct and the system has the proper refrigerant the next step is to check the heater control valve or air-blend door. These parts control the temperature of the air coming into the car. Heater control valves control the flow of hot coolant to the heater and air-blend doors mix hot and cold air together to achieve the desired interior temperature. So although the AC is cooling properly a faulty heater valve or goofy air blend door reheats the cooled air and you get warm or hot air inside the car.

Unfortunately, air-blend door problems are common and often caused by pens, pencils, toys, food and other “stuff” you place on the dash. That “stuff” falls through the defroster openings right into the heating and air conditioning ducts where it jams the air blend door. Fixing your seemingly tiny blunder can be a very big deal often gobbling-up several hours and hundreds of dollars.

Air conditioning operates by picking up heat from inside the car and dumping it into air moving through a radiator-like unit mounted in front of the car’s radiator called a condenser. Because of its position and importance to AC performance have the condenser examined for airflow-restricting dirt and debris yearly and whenever there’s an AC problem. Over time leaves, bugs, mud, and everything from plastic bags to dried road oil and general crud builds up on the front of the condenser and between the condenser and radiator. Cleaning the condenser is often all it takes to restore proper AC cooling.

Finally don’t forget to check your cabin air filter. Dirty cabin filters restrict air flow into the cabin and significantly reduce cooling. These are just a few frequently overlooked AC problems that’ll bite ya.

Remember to legally fix car air conditioners technicians must have an EPA license and should be ASE certified so ask if the tech working on your car is licensed first. Be wary of “cheap jobs” which often create a mess that is very costly to fix.

Published in by CARCHEX on November 13, 2014