It all started while I was driving the car around town. I had the air conditioning on because it was a typical hot, humid Kansas City summer day. As I neared my destination, the refreshingly cool air blowing from the vents vanished. Gone.
I rolled the windows down and continued on to my destination, sweating profusely. What could have caused the A/C to just suddenly stop? I put on my diagnostic hat and went through some initial checks. I observed that the A/C compressor was indeed turning on and that cool air was slowly coming out the vents (but not enough to even remotely cool the cabin). This was a relief seeing as how I had already overhauled the car’s A/C system.
These cars use an automated climate control unit which is overly complex and is just asking to break. I figured it was possible that something had gone wrong with it and that maybe a sensor was telling the blower motor to not run when the A/C was turned on. So, with that theory, I set the climate control temperature to “Hot.” With full cabin heat engaged, the blower motor still wouldn’t push air out the vents. Dang, so much for that idea.
I made it home and pulled the car into the garage. It was time to dig deeper into the problem at hand. I had determined that the root of the issue was the blower motor not turning on. After all, it is this electric fan which propels air out the vents in the first place. However, the question remained: Why wasn’t the motor working?
Against all odds, the blower motor is actually easy to access on the 300ZX. I removed a plastic kick panel, popped out the glove box, and there it was.
The first thing I wanted to do was test whether or not the blower motor was getting power. To do this, I removed the motor’s electrical connector and hooked up my voltmeter to the plug’s terminals. With the car on and the A/C on full blast, I took a voltage reading from the plug. I saw 11-12 volts on the voltmeter. This was great news because it meant that everything upstream of the blower motor was working correctly. Unfortunately, it also implied that the blower motor was dead.
Armed with that knowledge, I decided to pull the blower motor out of the car and see if I could repair it. If I couldn’t fix it, then I would have to open up my wallet and wait a week for a new one to be delivered.
Removing three screws was all it took to pry the blower motor out from under the dashboard. I had to wrangle with some wiring and dashboard brackets but it eventually the motor was free. With the blower set on the bench, I was glad to see that Nissan had designed it to be disassembled - a detail proven by two small screws securing the motor’s end cap to the main motor body.
Unaware of what might lie within, I removed the two screws and popped the end of the motor off.
Well, that must be the problem! I determined that the debris inside the motor was deteriorated insulating foam the car’s HVAC ducting. It seemed strange to me that it ended up inside of the motor instead of blowing out the cabin vents. Oh well, all I knew is that it had no purpose being in there and that the motor needed a complete strip-and-clean.
With the motor completely disassembled, I sprayed every component down with some electric parts cleaner. It all cleaned up surprisingly well and looked in reasonably good shape. I was feeling confident that when reassembled, this baby would start right back up.
I placed a small amount of oil on the armature bearings on each end of the motor then reassembled everything. The motor spun freely when turned by hand. I reinstalled the motor under the dashboard and immediately went to test out the A/C system.
With the car turned on the A/C system set to full tilt, a welcomed rush of air came pouring from the vents. Hell yes! I had somehow just managed to fix the Z for free in under three hours.
Most people steer clear of cars like this vintage, fearing these kinds of small problems. You imagine yourself awaiting a sea of broken plastic clips, impossible-to-repair parts, and a life of endless indignities. But it’s not always like that. This was still an era when cars were built with maintenance in mind, at least in some cases.
Even for owners, the Nissan 300Zx Twin Turbo is a love-hate relationship. When everything is working right, it fulfills all sports car needs. When it breaks, it leaves you wondering what side of a four-figure repair bill it will fall on. This time, the Z gave me a free pass—even if it is just to the next breakdown.