Question: The air conditioner on my Toyota recently stopped blowing cold air. A salesman at a parts store told me that my system probably needs recharging and that he could sell me the refrigerant kit. Is this something I should attempt to do on my own?--H.H.
Answer: Almost every auto-parts store and automobile section of discount stores sells refrigerant kits that permit backyard mechanics to recharge their air conditioners. Unfortunately, there will be many accidents because of it.
As summer approaches, many motorists will need to have their air conditioners recharged. The Freon gas inside their charging system often dissipates during the long winter months, and their cooling capacity is significantly reduced.
But the recharging of an automobile air conditioner is not something that an individual with no training should attempt to do. If you overcharge the system, meaning that you put too much pressure into the system, you can ruin the compressor.
Worse yet, if you attempt to charge the wrong side of the system, the can of Freon gas can explode. In the worst possible case, an engine fire could cause the Freon to explode, and the burning of Freon creates a poisonous gas that can cause blindness.
If you are determined to do this on your own, however, I suggest that you purchase a book that will explain the theory and operation of refrigeration systems. I strongly advise against relying on the instructions printed on the backside of the kit box. They are totally inadequate.
Q: When we recently bought a Toyota Landcruiser, all the paper work said it was a 1983 model. We took it in for some minor work, and the service man said it was really a 1982 model because the metal tag on the door frame says "NOV 1982." Is he correct or is it really a 1983 model that was manufactured in 1982? We bought it from a dealer in 1985, and we are concerned whether we would have any recourse now.--L.B.
A: The vehicle is a 1983, even though it was manufactured in 1982. Toyota starts its model year in August of the previous year, the same way that American auto makers have for years.
A second way you can check the model year is with the vehicle identification number or VIN code. The code starts with an alphabet. The letter B is for the model year 1981, C for 1982, D for 1983 and so on.
Q: I had spark plugs replaced at 15,000 miles on my new Dodge 600 at a dealership. After moving across country, I took the car in for a tuneup, and the mechanic said the plugs had been cross threaded by the last mechanic. Two of the four cylinders had stripped threads. Does with happen often with engines that have aluminum heads?--A.D.
A: The technology of aluminum heads and blocks in auto engines has come a long way since they were first used in the 1960s, but they are still far more fragile than a cast iron engine.
Aluminum blocks and heads disperse heat much better than iron and they are lighter in weight. But they do require much greater care in servicing. Spark plugs should always be started by hand on any engine but especially on aluminum.
Aluminum is a much softer metal, and it strips much more easily than iron. It is also a good idea to use a torque wrench on an aluminum engine. Typically, spark plugs are torqued to 25 foot pounds.
Ralph Vartabedian cannot answer mail personally but will respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, You section, The Times, Times Mirror Square, Los Angeles 90053.