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Not all air conditioning problems are in the air conditioning system

Wednesday, May 1, 2019 - 07:00
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It’s no surprise on a hot summer day that a customer greets you at the service desk stressed out over their car. Their car isn’t keeping them cool, it’s uncomfortably hot, they’re perspiring, and they’re probably more than a little temperamental about it. All because today of all days, with all the plans they had made, the car decides to have a non-functioning air conditioner. To make matters worse, the vehicle was recently in the shop (hopefully not yours) for some unrelated work, and now that the air conditioning is out, it most obviously is related to what was done the last time it was in the shop. And, of course, it’s entirely the mechanics fault.

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Whatever the case maybe, the real issue isn’t the who done it but what is actually wrong, and how are you going to solve their problem. So where do you start to solve this issue quickly and efficiently?

If this is what you see with the air conditioner on, and the head pressure is rising, start looking for causes and cures relating to the coolant fan and not necessarily the air conditioning system.

As with any diagnostic work, the challenge is to isolate and find the cause and not so much the results that have brought the customer to your door step. We know why they’re here, let’s find out how to get you back on the road. The first thing is to listen to the customer, but keep in mind, the problem can be two fold. One, the customer’s assumptions can be perhaps… misleading, and two, the air conditioner’s lack of cooling the interior may not be the air conditioner’s fault.

For this article, we’re going to go through a few case studies where the cause of the failure wasn’t the previous shop, or the air conditioning system itself. Instead, these studies bring up the point that it could be something that effects the actual air conditioner’s performance. I’m not going to dwell too much on the technical side of the repairs, but on how you can use your investigative skills to read between the lines of the customer’s story and sort out what is really the issue.

Case #1:  The dog did It 

Besides the customer’s name, phone number, and address, the first thing on any work order should be what the nature of the customer’s complaint is. With that information in hand, you can observe and verify the problem areas of the vehicle using the customer’s explanation as a guide.

“Before we can repair, we must be aware” is my little slogan that I often used when diagnosing a problem.

Now, I know this sounds like the same old thing you’ve read in every diagnostic article, but it’s so true. Do the basics first. Observe, check circuit fuses, grounds and communication. (Not necessarily in that order) Doing the preliminary work is part of every diagnostic even if it’s a drivability concern. Even if the customer only came in because the radio won’t tune to their favorite channel. You have do the basics.

In this particular case, you could have started with checking pressures with a set of gauges, or you could have simply used your thermal gun and checked the system’s temperature at various points to determine whether or not the refrigerant load was within specs. However, sometimes listening and observing (to the car and the customer) is the most important part of the diagnostics.

As his story goes, he uses this particular vehicle as a pilot vehicle for large wide loads that are transported across the country. He travels through various climate zones and long distances with lots of hours behind the wheel. Meaning, a lot of the vehicle’s systems are on for hours and hours. All of which could play a factor in this case, but there’s one more detail that he briefly mentioned just which led to the solution. 

The bed of his truck is set up like a traveling hotel room with all the creature comforts of home. He also brings along his favorite companion, a 3-year-old English Shepherd named Jake. 

English Shepherds are known to shed their coats profusely, and Jake spends most of his driving time lying down on the passenger floorboard right in front of the recirculation vent. The recirculation system worked more like an automatic fur removal machine than anything else.  The blower motor would suck the loose fur off of Jake through the recirculation vent and deposit it on the surface of moist evaporator core where it stuck like glue. After sometime, the fur would collect into a nice flat matt of hair, almost like a layer of felt.

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