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March 24, 2010
Pre-Summer A/C Inspections
The heat of summer is just a few short months away, so the time to begin paying attention to your customers’ air conditioning system has arrived.
Some shops may decide to offer their customers A/C performance testing—either invasive (checking system pressures) or not (function and temperatures only)—but there are other components that require attention, and some of these can be checked quickly and easily while performing other maintenance.
The oft-forgotten drive belt
Perhaps the most overlooked components of the air conditioning system are the drive belt and tensioner. Even though the compressor may already have been automatically coming on with the defroster on warm days without incident, it has yet to place the kind of loads on the drive system that the high system pressures of the hot days of summer will.
A quick visual inspection of the belt and the drive pulleys can reveal not only a worn or damaged belt, but in the case of multirib belts, misaligned components. In particular, look for exposed shiny areas on metal pulleys that indicate that the belt’s position has recently deviated from an earlier wear path. This may be a sign of a worn tensioner, or possibly a failing bearing in a water pump or other accessory.
In many vehicles the springloaded tensioner can be checked for sticking or seizing by tugging or pushing on the belt enough to deflect the mechanism’s arm.
Keeping it cool
Winter can be tough on air defl ectors and condenser fi ns. Many newer vehicles bring the majority of their cooling air in from below the front bumper. If a snowbank has removed the air defl ector that many carshave beneath their radiator support, highway speed cooling performance can suffer, since the airfl ow passes beneath the vehicle instead of being forced through the condenser and radiator.
Winter damage can also extend to the condenser fins or even the condenser itself.
I’ve actually had the odd customer vehicle where the rad opening is still stuffed full of fall leaves in the spring. More commonly, the leaves fi nd their way into the fresh air intake in the cowl or the cabin fi lter, where they can reduce heater system airflow and cause odours—this is common in GM minivans, and will affect A/C performance.
Control check
It seems obvious to verify whether or not the heater system’s blend door can change from warm to cold, but there is often an underhood partner to the blend door in the form of a coolant shutoff valve. This valve is frequently actuated by a vacuum motor, but in many import models is controlled by a cable linked to the heater’s temperature control.
While not always as easy to check as a belt or condenser, it’s a good idea to verify its operation during an A/C inspection; failure of this valve to block coolant fl ow can result in warmer than desired outlet air temperatures as the heater core bleeds heat into the system’s components.
Whether as part of an A/C inspection, or just a valueadded courtesy for your clients, a few extra seconds spent can benefit both you and your customer.
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Brian Early
