As a technician, I’ve seen my fair share of electrical gremlins – we call them “Purple Monkeys” around here. On a recent service call for a malfunctioning awning left me scratching my head—and taught me a valuable lesson about the quirks of fuses. The customer reported that their awning wouldn’t extend or retract, so I headed out to diagnose the issue.
Volts & Amps
Voltage is like water pressure (PSI) in a hose—it’s the force pushing electricity through a circuit. Amperage (amps) is like the flow rate (gallons per minute)—it’s the amount of electricity flowing. You might have high PSI (volts) at the nozzle, but if the hose is pinched, you get low flow (amps), and your device won’t run. Both volts and amps need to be adequate, just like a sprinkler requires both pressure and flow to water your lawn effectively.
The Initial Diagnosis
Upon arrival, I tested the power at the plug and found a solid 12.8 volts—plenty to run the motor. The symptoms indicated a faulty motor, and a quick check with my diagnostic tool (affectionately called the “coddi”) confirmed it. I replaced the motor, expecting the awning to spring to life. But, to my surprise, the new motor didn’t budge either. The monkey was still lurking. I started to see a broken wire coming up, worse one in the wall or under the belly.
Digging Deeper
I wasn’t about to let this puzzle beat me. The customer mentioned they’d checked the fuse and thought they saw a “very faint glow” across a blown fuse indicator. I didn’t observe this glow myself, but it planted a seed of doubt. I pulled out my multimeter and tested the fuse: 12.7 volts, just shy of the full 12.8V at the plug. Slight variances are common. Everything seemed fine, right? Wrong.
Despite the voltage reading, something felt off. A fuse showing voltage but failing to deliver power to the motor hinted at a sneaky issue—one I’d encountered in electrical theory but rarely seen in the field.
The Culprit: Voltage Without Amperage
Here’s where things get interesting. A fuse can sometimes conduct just enough to show voltage on a multimeter but not enough to carry the amperage needed to power a device. In this case, the motor required a significant amount of current (amps) to operate, but the compromised fuse wasn’t delivering it. The multimeter, which draws almost no current, happily reported 12.7 volts, masking the real problem: the fuse’s internal connection was too weak to handle the motor’s current demand.
Think of it like a garden hose with a tiny pinhole. You might measure water pressure at the nozzle, but if the hole’s too small, you’re not getting enough flow to water your plants. Voltage is the pressure; amperage is the flow. Without both, your device—whether it’s an motor or a garden sprayer—won’t work.
The Fix
Before replacing the fuse, I ensured the underlying issue (likely a short or overload that caused the fuse to weaken) was resolved by verifying the new motor and wiring were sound. Then, I swapped out the suspect fuse for a new one. The result? The awning extended and retracted smoothly as if nothing had ever been wrong.
The Takeaway
This experience was a reminder that electricity isn’t just about voltage. A multimeter can fool you into thinking everything’s fine when it’s not. If a device isn’t working despite a good voltage reading, check the fuse’s ability to carry current. A weak or partially blown fuse can pass just enough electricity to show voltage but fail to deliver the amps needed for operation.
Next time you’re troubleshooting, don’t let a “good” voltage reading lull you into complacency. If the device isn’t working, dig deeper—your monkey might just be a sneaky fuse playing tricks.
Stay Where You Are, We’ll Be Right There
As with all of our work, our team will come to you. There is no need to transport your camper or RV to a facility, leave it for days or weeks, only to have to go pick it up again. Whether it is in your driveway, a camp-site, or in storage, we will do our best to accommodate your needs, schedule, and location.
Just contact us, and we’ll take care of the rest.
