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To quote or not to quote is a mechanic’s slippery slope

Mechanically Speaking; by Trail Times Columnist Ron Nutini
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Automotive repair and maintenance is a competitive business. Consumers have choices when it comes time to get their vehicles repaired or maintained. Inevitably many consumers approach auto repair in the same way they buy goods. They price shop.

Trying to remain professional while not seeming cruel and indifferent when confronting the price shopper is like treading in quicksand. You are ‘damned if you do or damned if you don’t’. You can’t really quote most automotive repairs without seeing the car.

As summer approaches a common quote request is “How much to fix my air conditioning?” The only real answer is “it depends”. It depends what is wrong and I have to do some diagnostics to figure out what is wrong.

Definitely there are common air conditioning failures that all result in warm air instead of cold air. A new air conditioning clutch relay may get you your cold air back for mere peanuts where as replacing your evaporator will make you think about living without cold air. Briefly, I might add.

“Well how much just to recharge my air conditioning? That is all I really need”. My turn. “How do you know all you need is a recharge?

An air conditioning system is a closed loop of refrigerant and oil that is circulated by a compressor (pump) through hoses and lines and two radiator type devices called a condenser and evaporator. The compressor raises the pressure of the refrigerant and pushes it through the condenser.

At high pressure the refrigerant is changed from a gas to a liquid by flowing through the condenser, a radiator type device mounted across the front of your vehicle. The air flowing across the condenser removes heat from the refrigerant changing it from gas to liquid. The air flow is natural when the vehicle is moving fast enough but at low speeds a fan or fans are required to do the cooling.

In the liquid form the refrigerant now passes through a restriction or valve and into the evaporator within the bowels of your dashboard. The evaporator absorbs the heat from the air in the vehicle by changing the refrigerant from a liquid to a gas again. Again a fan is involved. The one that blows the cold air in your face.

Suffice to say a lot of science is involved.

If your refrigerant is low or empty and the system needs recharging the next question is why? Slow leak, or fast leak? We have to find out. We can not recharge a leaking system. It will just leak back out again and make a very unhappy customer. Fast leaks are easier to find but generally more expensive to fix (broken parts). Slow leaks are harder to find. Sometimes fixing the leak can be quite easy. Leaking o’ring seals in a reasonably accessible location come to mind.

Even once leaks are found and repaired and the system is recharged proper operation must be confirmed.

So I must counter the question “How much to recharge my air conditioning system” with “Let me diagnose the problem first.” Then we can formulate a plan and look at cost.

Most vehicle systems are similar. Proper diagnosis is required to quote a reasonably accurate amount to repair a vehicle.

Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: nutechauto@telus.net