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.
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?
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.
As I listened to his story, my customer had no idea he was telling me exactly where the problem was. His description of how good of a dog Jake was and how he would stay right there on the floor just watching him drive on a hot afternoon also told me this wasn’t a once in a while adventure.
In this case, the air volume from the vents was the issue. So, why in this case does this problem stick out as the probable cause of the air conditioning failure more than anything else? Listening to the customer’s story intently, knowing that this time of dog has a tendency to let the fur fly, and knowing the operational workings of this particular air conditioning system. It all added up to some simple detective work that arrived at the solution to the problem without a single tool involved.
Obviously, the core had to come out. Once the core had been removed you could clearly see that the evaporator core was a solid wall of dog fur. What is even more remarkable, he didn’t mention or noticed the muffled sound from the blower motor. The gradual clogging of the evap. core had happened so slowly that the eventual drop in the air flow wasn’t even noticed over those long trips.
The solution: Replace the core, clean the ducting, and a new blower motor wouldn’t hurt either. Then, add a filter in front of the recirculation grille to catch the dog hair that could be easily cleaned with Jake had another flurry of loose fur. Problem solved.
Case #2 – Too much pressure
Talk about head pressure! Some customers just have to blow off steam when they come into the repair shop. Whether it’s from some poor information or bad service or they’re just too dang hot under the collar for much more than a good old fashion rant at the service counter. This time around it’s an early 2000 Buick with an air conditioning problem, or at least that’s what the customer assumed it was.
Each time the air conditioning was turned on it would turn off after a few minutes if not sooner. The car was at another shop that had quickly made the call to replace the entire system. This customer wasn’t buying that diagnosis. Again, the key to the start of this diagnosis was to listen to the customer’s story. As in a lot of these stories, you tend to get a bit lethargic, if not sleepy listening them. But you just have to, it’s important.
Think of it this way, don’t listen to the story, listen to what they’re not telling you. I’m actually listening for things like the time of the day, how long they’ve drove the vehicle, or how often the problem occurs. Ask questions like, what were the driving conditions, is it in any way predictable, and ask if they can make the problem happen now. The intermixing of grandma’s chocolate cookie recipe and the kid’s basketball game are not much help in regards to the diagnostic make up but it is part of the story, so you best act like you’re interested in those cookies too.
After pulling the car into the service bay the first thing to do was to simulate the problem and observe the results. I always say that diagnostic work involves looking and examining, not repairing or adjusting. Whether that includes a scanner read or just quick lean over the fender it all falls under the umbrella of the diagnostic fee. However, if you move, disturb, change, adjust, or tighten a bolt you’re NOT diagnosing. If to further your diagnostic work you have to install a drive belt, evacuate and recharge the system, that’s not diag. work, that’s part of a repair and you should charge accordingly. You can continue the diagnostics after that particular work has been completed.
This time around, the diagnosis was rather simple. Hook up a set of gauges and observe the pressure changes. As the compressor would click on it would only take a few minutes before the high side pressure started to rise higher and higher to the point it reached the high side limit and drop the voltage to the compressor. In this case, it wasn’t the air conditionings fault at all, it was the cooling fan. No fan pulling air through the core raised the internal pressure of the air conditioning system to the danger point.
The solution: replace the coolant fan. This time around the connections were perfect, just the fan was bad. The best part was the air conditioning head pressure calmed down as quickly as the overheated customer. Just hope grandma has some of those cookies backed.
What’s the future hold?
These days with the “learn strategy” methods of operation, things are quite different. The vehicle’s computer can make little adjustments to various systems to maintain them in the desired range of operation. Things like controlling a desired torque response that compliments what the customer feels while driving as well as shift points and emissions levels. The typical A/C compressor engagement that would drop the rpm level slightly can now be mapped out of the system by adjusting the electronic throttle and the use of the PWM compressors also eliminates the stress on the belt as well as the compressor. (The electrically operated compressors are even eliminating even more of those internal stress loads.)
This can also mean the story from the customer may take on a completely different aspect to the repair. With every component and system that are being interconnected with the next system can make diagnostic work that much more of a challenge. Today unlike in previous years, listening to the customer’s story may be even more important than ever before. The customer’s understanding of the inner workings of today’s cars will be even more limited than in the past. So, cooling off that hot customer at the service counter may take a bit more understanding and listening than ever before. (Might ask grandma for an extra batch of those cookies for your service counter.)
