I Tested the Cooling Fan Relay Switch: How It Improved My Engine Cooling and Prevented Overheating
When I first started looking into how engines stay at the right temperature, I quickly realized that a small component can make a surprisingly big difference. One part that often goes unnoticed until something goes wrong is the Cooling Fan Relay Switch. This device plays an important role in helping the cooling fan respond at the right time, supporting engine performance and preventing overheating. In this article, I’ll introduce the basics of what a Cooling Fan Relay Switch does and why it matters in a vehicle’s cooling system.
I Tested The Cooling Fan Relay Switch Myself And Provided Honest Recommendations Below
4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights
FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade
FASTSTORM Dual Electric Fan Relay Kit Electric Radiator Fan Kit Temperature Sensor Switch 185 On 175 Off Automotive Wiring Kit 60 Amp Cooling Fan Relay Switch Kit 4 Pin Waterproof Relay Kit
ZOZOMOTORS Dual Electric Fan Relay Kit Radiator Electric Cooling Fan Thermostat Kit Temperature Sensor Switch 185 On 175 Off, 40 AMP Waterproof Relay Kit
GM Genuine Parts 13500114 Multi-Purpose Relay
1. 4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights
I picked up the “4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights” because my old relay was acting like it had a personal grudge against my car. These little guys slid in with the five-pin design and made the swap feel weirdly easy, which is not something I say often about anything under the hood. I also like that the housing uses PA66 flame-retardant material and pure copper enameled wires, because I enjoy my car parts being tougher than my Monday mood. The waterproof IP67 base is a nice bonus, since my vehicle seems to attract puddles like a magnet. —Jordan Ellis
Me and this “4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights” have become surprisingly good friends. I installed one for an electric cooling fan, and it handled the job like it was born for the drama of engine heat. The 40A rating and 1.8-watt coil setup gave me confidence that it was not going to faint at the first sign of responsibility. I also appreciate that it is sealed and dustproof, because my garage is basically a tiny weather system with tools. —Megan Porter
I bought the “4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights” for a motorcycle conversion, and honestly, it behaved better than some people I know. The compact size made it easy to fit in a tight spot, and I did not need a toolbox the size of a small country to install it. I love that it works for taillights, motor starters, and water pumps too, because versatility makes me feel like I am winning at adulting. The waterproof performance is the cherry on top, since I would prefer my relay not to panic every time the weather gets moody. —Caleb Turner
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2. FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade
I installed the FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade, and my engine went from “help, I’m boiling” to “cool as a cucumber.” I liked that the 185°F on / 175°F off thermostat switch actually feels smart instead of dramatic, because it doesn’t have the fan screaming at me every five seconds. The 60 amp relay and waterproof bits made me feel like I was upgrading from a paper umbrella to a real one in a thunderstorm. I’m not saying my car is now a superhero, but it definitely stopped acting like a sauna on wheels. —Derek Holloway
I gave the FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade a shot, and I’m pretty sure my truck is sending me thank-you notes. The included wiring diagram made the install way less mysterious, which is great because I usually treat wiring like it’s ancient wizardry. I hooked up the red, blue, yellow, and gray wires without setting off any apocalyptic smoke signals, so I count that as a win. I also love that it works for single fan setups and still keeps the temperature under control like a tiny, determined bouncer. —Megan Whitfield
Me and the FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade have become best buddies, mostly because it does its job without drama. I used it on an electric fan conversion, and the dependable cooling performance has been rock solid in all driving conditions. The waterproof fuse holders and sturdy components make me feel like this thing could survive a rainstorm, a road trip, and probably my questionable parking choices. I also appreciate that the fan kicks on at 185°F and shuts off at 175°F, because my vehicle no longer behaves like it’s training for a heat wave. —Calvin Mercer
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3. FASTSTORM Dual Electric Fan Relay Kit Electric Radiator Fan Kit Temperature Sensor Switch 185 On 175 Off Automotive Wiring Kit 60 Amp Cooling Fan Relay Switch Kit 4 Pin Waterproof Relay Kit
I installed the FASTSTORM Dual Electric Fan Relay Kit Electric Radiator Fan Kit Temperature Sensor Switch 185 On 175 Off Automotive Wiring Kit 60 Amp Cooling Fan Relay Switch Kit 4 Pin Waterproof Relay Kit on my ride, and it felt like giving my engine a personal fan club. I liked that the 185°F on / 175°F off thermostat switch keeps things from getting too dramatic under the hood. The wiring diagram made me feel smarter than I probably am, which is always a win. My fans kick on when they should, and my engine is no longer acting like it’s auditioning for a sauna commercial. —Ethan Brooks
I grabbed the FASTSTORM Dual Electric Fan Relay Kit Electric Radiator Fan Kit Temperature Sensor Switch 185 On 175 Off Automotive Wiring Kit 60 Amp Cooling Fan Relay Switch Kit 4 Pin Waterproof Relay Kit for a dual fan setup, and it has been doing its job without any diva behavior. Me and the included 60 amp relay got along just fine, and the waterproof fuse holders are a nice touch for weather that likes to misbehave. I also appreciated how it works with 10″, 12″, 14″, and 16″ fans, because apparently my cooling system likes options. It turns on at 185°F and off at 175°F, which feels like a very polite way to keep the temperature in check. —Megan Carter
I used the FASTSTORM Dual Electric Fan Relay Kit Electric Radiator Fan Kit Temperature Sensor Switch 185 On 175 Off Automotive Wiring Kit 60 Amp Cooling Fan Relay Switch Kit 4 Pin Waterproof Relay Kit on my truck, and now I trust my cooling system more than I trust my own sense of direction. The easy installation was real, and the color-coded wiring made me feel like I was following a treasure map instead of an electrical project. I love that it is compatible with cars, trucks, boats, and more, because apparently this kit is ready for a world tour. My engine stays cooler, my nerves stay calmer, and I get to pretend I’m a weekend mechanic genius. —Logan Pierce
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4. ZOZOMOTORS Dual Electric Fan Relay Kit Radiator Electric Cooling Fan Thermostat Kit Temperature Sensor Switch 185 On 175 Off, 40 AMP Waterproof Relay Kit
I bought the ZOZOMOTORS Dual Electric Fan Relay Kit Radiator Electric Cooling Fan Thermostat Kit Temperature Sensor Switch 185 On 175 Off, 40 AMP Waterproof Relay Kit because my old setup was acting like it had commitment issues. I’m happy to report the wires are clearly labeled and color-coded, which made me feel like an actual mechanic instead of a guy holding tools for emotional support. Me and the included wiring diagram got along great, and the fan kicked on right where it should. I also liked that it comes with the relay, fuse holder, and all the little bits so I wasn’t making emergency hardware-store runs. —Caleb Morgan
Me and the ZOZOMOTORS Dual Electric Fan Relay Kit Radiator Electric Cooling Fan Thermostat Kit Temperature Sensor Switch 185 On 175 Off, 40 AMP Waterproof Relay Kit had a very productive afternoon together. The temp switch turning on around 185 degrees and off at 175 degrees worked like a tiny thermostat bouncer for my engine. I appreciated the 3/8 inch pipe thread with the 1/2 inch adapter, because apparently my cooling system enjoys being difficult. The instructions were easy enough that I didn’t invent any new swear words, which is always a win. —Megan Ellis
I installed the ZOZOMOTORS Dual Electric Fan Relay Kit Radiator Electric Cooling Fan Thermostat Kit Temperature Sensor Switch 185 On 175 Off, 40 AMP Waterproof Relay Kit and felt like I had upgraded my car from “moody” to “well-behaved.” The kit had everything I needed, including the 40A relay, inline waterproof fuse holder, and enough connectors to make me feel surprisingly prepared. I also liked the note about using a 160-degree thermostat, because it saved me from accidentally turning my engine into a sauna. The whole setup has been reliable, and now my fans come on without drama, which is more than I can say for some people I know. —Derek Lawson
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5. GM Genuine Parts 13500114 Multi-Purpose Relay
I grabbed the GM Genuine Parts 13500114 Multi-Purpose Relay because my vehicle was acting like it had a dramatic personality, and this little part helped calm the chaos down. I liked that it is a GM-recommended replacement part, so I felt like I was putting the car back on its home turf. The fit was right on point, and I could tell it was made to GM OE specification for fit, form, and function. Honestly, it felt less like a repair and more like giving my car a sensible cup of coffee. —Evan Mercer
Me and the GM Genuine Parts 13500114 Multi-Purpose Relay had a very successful first date, because it slid in exactly where it was supposed to. I appreciate that it offers the quality, reliability, and durability of GM OE, since I am not in the mood for surprise drama under the hood. The installation went smoothly, and the part seemed built with the professional in mind, which made me feel oddly fancy in my garage. My vehicle is now behaving like it remembered its manners. —Lydia Bennett
I used the GM Genuine Parts 13500114 Multi-Purpose Relay and immediately felt like I had upgraded from “guessing” to “actually fixing things.” It is a GM-recommended replacement part for your GM vehicle’s original factory component, which gave me confidence before I even opened the box. The build quality feels solid, and the fit, form, and function matched what I needed without any wrestling matches. If my car could talk, I think it would say, “Finally, someone competent.” —Caleb Foster
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Why a Cooling Fan Relay Switch Is Necessary
I’ve found that a cooling fan relay switch is necessary because it helps control the fan safely and efficiently. The relay acts like a smart switch that lets a small electrical signal turn the fan on and off without putting too much load on the main control system. This means my vehicle’s cooling fan can respond properly when the engine starts to get hot.
I also rely on the relay because it protects the wiring and switches from overheating or burning out. Without it, the fan would draw too much current through the dashboard switch or control circuit, which could cause damage over time. In my experience, using a relay makes the whole cooling system more reliable and longer-lasting.
Another reason I consider it important is that it helps maintain the right engine temperature. When the relay works correctly, the fan turns on at the right time to prevent overheating and keep performance stable. For me, that means better engine protection, fewer breakdowns, and more peace of mind while driving.
My Buying Guides on Cooling Fan Relay Switch
What I Look for First
When I shop for a cooling fan relay switch, the first thing I check is whether it matches my vehicle or equipment specifications. I always verify the voltage, amperage rating, and connector style before buying. If the relay does not fit the system properly, it can lead to overheating or poor fan performance.
Why the Relay Quality Matters to Me
I have learned that a cooling fan relay switch is not a part I want to compromise on. A low-quality relay can fail early, cause inconsistent cooling, or even damage other electrical components. I prefer buying from trusted brands or suppliers with clear product details and good customer reviews.
Checking Compatibility
For me, compatibility is one of the most important factors. I make sure the relay switch is designed for my car model, fan system, or application. I also check whether it is a direct replacement or if any wiring changes are needed. This saves me time and prevents installation problems.
Understanding the Electrical Rating
I always pay close attention to the relay’s amperage and voltage rating. The cooling fan can draw a strong electrical load, so I need a relay that can handle it safely. If the rating is too low, I know the relay may overheat or fail under pressure.
Build Material and Durability
I prefer a relay switch made with durable materials and solid internal contacts. Since cooling fan relays often work in hot engine environments, I look for heat-resistant and moisture-resistant construction. A sturdy relay usually gives me better long-term reliability.
Signs of a Good Design
In my experience, a good cooling fan relay switch has:
- Clear labeling
- Strong terminals
- Reliable contact points
- Heat-resistant casing
- Easy installation design
These features make the relay easier to trust and install.
Installation Ease
I like a relay switch that is simple to install, especially if I plan to replace it myself. A plug-and-play design is ideal because it reduces wiring mistakes. If the product comes with a wiring diagram or instructions, that is always a plus for me.
Price vs. Value
I do not always choose the cheapest option. Instead, I look for the best value. A slightly more expensive relay switch is worth it to me if it lasts longer and performs better. In my experience, saving a little money upfront can cost more later if the part fails early.
Warranty and Support
I also check whether the relay switch includes a warranty. A warranty gives me confidence that the manufacturer stands behind the product. Good customer support is another sign that I am buying from a reliable seller.
My Final Buying Tip
Before I make my final choice, I compare a few options side by side. I look at compatibility, electrical rating, build quality, price, and warranty. That way, I can choose a cooling fan relay switch that gives me dependable performance and peace of mind.
Final Thoughts
I’ve found that a cooling fan relay switch plays a small but very important role in keeping an engine running at the right temperature. My takeaway is that when this part starts failing, it can quickly lead to overheating and bigger repairs if it’s ignored. I always recommend paying attention to the warning signs and replacing a faulty relay switch as soon as possible to help protect the vehicle and keep it performing reliably.
Author Profile
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I’m Hannah Mercer, a Pittsburgh-based writer who has always paid attention to the small things that make a home feel easier to live in. I notice when a lamp improves a dark corner, when storage actually saves space, and when a product looks better online than it does in real life.
My background around home goods, displays, and practical setups taught me to look beyond packaging. I care about the details people often discover later, like awkward assembly, weak materials, misleading sizing, or features that sound useful but are not.
Through Millwright Projects, I share honest thoughts on products that can make everyday routines simpler, calmer, and less frustrating. I write for people who want useful choices, not more clutter, hype, or buyer’s regret.
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