Notes from Maine - 2021/09/19

I drive a 2005 GMC Envoy. Once a year or so, I’ll pull up at a red light and there will be another Envoy next to me. I always turn to lock eyes with the other driver for a moment. We share a frown and a solemn nod. There’s a deep disappointment and fear that every Envoy driver knows. Each mile that passes beneath the groaning tires might be the last. Each time we press down on the accelerator, it’s an act of illogical optimism. 

About 12 years ago, just as the warranty was expiring, I realized that there would always be three things wrong with the Envoy. In the beginning, it was silly stuff. For example, the blower motor stopped working. I would turn the dial and no air would come out. In Maine, driving around in snot-freezing temperatures half the year, a vehicle without a working heater is useless. This was days after the warranty expired. I took it to the dealer and they demanded $300 to fix the issue.

“What’s wrong with it?”

“The blower motor resistor is bad,” they said.

This simple statement sent me down a rabbit hole of mental trauma.

“This vehicle is three years old. Clearly, this part should last for more than three years, right?”

“Unfortunately,” they said, “these go bad all the time.”

“Then it’s defective. I have ten-thousand miles on this thing. Why isn’t this covered as a defect?”

“The warranty has expired, sir,” they said with an exasperated sigh.

They sounded exasperated. I was just coming to terms with the idea that I had been sold a vehicle where random parts would “go bad all the time” and that concept was not considered defective. Somehow, that made them exasperated. I know, I know, I was just talking to a person who had no decision-making authority and had to deal with angry customers all day, but it would have been so much easier if they had expressed shame, guilt, or empathy. Instead, they started addressing me as “sir” with a definite tone.

It started earlier, of course. The Envoy would randomly stall. It happened mostly in parking garages. At low RPM, if I was making a slow left turn as I navigated the parking garage at work, the Envoy would just die. Suddenly, I would find myself in a low-speed panic with no power steering, stiffening brakes, and a bunch of flashing lights on the dashboard. For the first couple of years of owning the vehicle, I took it back to the dealer four or five times just for the stalling issue. They always said the same thing, “We can’t reproduce the issue.”

Another fun problem was the back window. To open the window on the tailgate, there’s a button. In those first couple of years, about half the time I pressed it, the button would stick in. Every time I took the vehicle back to the dealer, they would say, “We fixed the button.” That really meant that they just took it apart and unstuck it. The issue remained.

Before you ask—yes, I did write all this at the time in a “polite” letter to the dealer and GMC. I expected (and received) no response.

Anyway, back to the blower…

That was the problem that broke my heart more than any other. It’s such a simple thing. There’s a simple DC motor in the cabin vents that can run at various speeds, and a five-position knob on the dash to control it. I started my adulthood with a BS in Electrical Engineering, so I have some training in these concepts. 

In order to get the motor to run at five different speeds, there are several good options. I could wire up a pulse width modulated (PWM) voltage that would send power in little bursts to the motor. Imagine flicking the on/off switch at different rates to control the speed. This method is efficient, but requires more complex parts than other designs. 

The easiest way to vary the speed of a DC motor is with different voltages. Send the motor the full 12 volts that the car generates, and we have full speed. Send it less, and the speed reduces as well (the field created by the coils is as strong as the voltage provided). 

To create those various voltages, one might design a circuit with one or more transistors. These types of circuits have been around since the 1950s. They’re well known. 

If one were to give up on creativity, the absolute simplest circuit would be to just put big, stupid resistors in the path of the motor. The biggest, dumbest resistor would be wired to the lowest speed on the knob. Most of the electricity sent through “1” would be eaten by the resistor so the motor would turn fairly slowly. The resistor consumes the power and generates heat, so the part has a big chunk of metal on the back to dissipate the excess heat from the squandered power. 

GMC (in their effort to create the simplest, cheapest design) decided that the climate system would always use as much power as possible when it was on. If the driver wants very little air, they just chuck the excess power overboard and run the fan slowly. With the fan on full speed and minimum speed, it always uses the same amount of electricity.

That alone is offensive to me. They sold me the least elegant solution to a very simple circuit.

What fully broke my heart is that their “simplest” possible design was so poorly constructed that it broke after less than three years and ten-thousand miles. 

That same “attention to detail” is still evident now, after fifteen years of driving.

Three or four things break every year. 

Why do I still have that Envoy? At least I’m not surprised when something else goes wrong with it. If I got a new vehicle, I would have to endure that same disappointment all over again, I’m sure. At least I know how to fix the Envoy most of the time.

Hope you’re well and driving safe. If you see an Envoy on the road, give them extra space. They might need it.