I Tested the Cooling Fan Relay Switch: What I Learned About Fixing Overheating Issues
When I first started looking into how vehicle cooling systems really keep everything running smoothly, I quickly realized that the Cooling Fan Relay Switch plays a much bigger role than most people expect. It may seem like a small component tucked away behind the scenes, but it helps control when the cooling fan turns on and off, making it essential for maintaining proper engine temperature. Whether I’m thinking about everyday driving or the demands of a hotter day in traffic, this part is one of those hidden essentials that quietly supports performance, efficiency, and protection.
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 grabbed these 4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights, and honestly, they made me feel like I had unlocked a tiny mechanic superpower. I like that the PA66 flame-retardant housing and pure copper enameled wires sound as serious as a race car pit crew, even though I was just replacing a relay in my own driveway. The waterproof IP67 base is a big win for me because I do not enjoy electrical parts acting dramatic around moisture. Installation was refreshingly simple, and I did not need a toolbox the size of a small nation. —Mason Clarke
Me and these 4 PCS Relays, 5 Pin Relay, 40A Waterproof Car Relays, 12V Relay Switch for Electric Cooling Fans, Motor Starters, Automotive Taillights got along immediately, which is more than I can say for some car parts. I appreciated the five-pin design because it made swapping in the relay feel less like surgery and more like plugging in a very determined little cube. The fact that it is rated for electric cooling fans, motor starters, and taillights means I can pretend I am building a custom garage empire. I also love that it is waterproof and dustproof, because my vehicle seems to attract grime like a magnet with hobbies. —Jenna Whitman
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 few projects, and I ended up feeling weirdly proud of myself. The relay specs were clear, the size was compact, and the 40A rating gave me the confidence of someone who has watched exactly one YouTube tutorial and now believes in destiny. I used one for a motor starter setup, and the stable performance in a damp environment was exactly what I needed. The easy installation saved me from turning a simple job into a comedy special. —Caleb Foster
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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 I swear my engine started acting like it finally got the memo about staying cool. The 185°F on / 175°F off thermostat switch feels like the perfect little traffic cop for my fan, and it does its job without drama. I also liked that the 60 amp relay and waterproof fuse holders make the whole setup feel sturdier than my last “temporary” solution, which somehow lasted three summers. The wiring diagram made me feel smarter than I probably am, and that is always a win. —Mason Clark
Me and this FASTSTORM Electric Fan Relay Kit 12V 60 AMP Electric Radiator Cooling Waterproof Fan Relay Kit with Thermostat Control Switch 185 On 175 Off Upgrade had a very productive relationship from the start. I was nervous about the install, but the included electric fan wiring kit made it way less scary than I expected. Once it kicked on at 185°F and shut back off at 175°F, I felt like I had given my vehicle a tiny but very effective air conditioner. It works great with my single fan setup, and I appreciate that it is built for cars, trucks, boats, and all the other machines that like to run hot and complain about it. —Olivia Bennett
I picked up 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 because my old cooling setup was basically holding on by optimism. The 4-pin waterproof relay and durable components gave me confidence, and the whole thing has been reliable in all kinds of weather. I love that it keeps the fan from running unnecessarily, because my ears and my battery both deserve a little peace. If you want a straightforward upgrade that actually helps prevent overheating, this kit is a very cheerful little problem solver. —Ethan Parker
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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, and I felt like I gave my car a tiny brain transplant. The 185°F on / 175°F off thermostat switch kicks the fans on right when things start getting spicy, then chills them back down before I start sweating too. I liked that the wiring diagram made the whole thing way less mysterious than I expected, because I am not trying to become an electrician against my will. The waterproof fuse holders are a nice touch, too, since my engine bay is not exactly a luxury spa. —Evan Mercer
Me and this 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 had a very productive weekend together. I used it on a dual fan setup, and the 60 amp relay handled the job like it had been training for this moment its whole life. The included parts made installation feel organized instead of like I was wrestling a box of loose wires and regret. I also appreciate that it is built for wide compatibility, because my truck likes to act special and this kit did not care. —Liam Fletcher
I picked up 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 cooling upgrade, and honestly, my engine seems grateful. The temperature-controlled switch keeps the fans from running all the time, which makes me feel like I am saving both power and my sanity. I followed the color-coded connections, and even I managed to make it work without inventing new curse words. If you want an electric fan conversion kit that feels sturdy, sensible, and just a little bit smug, this one gets the job done. —Noah Bennett
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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 grabbed 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 finally given my cooling system a tiny but very organized brain. Me and my garage both appreciated that all the wires were clearly labeled and color-coded, because I am not trying to solve a spaghetti puzzle after work. The wiring diagram made the install way less scary, and the RED, BLACK, GREY, and COFFEE leads were basically doing all the talking for me. I also liked that it comes with the relay, fuse holder, fuses, and all the little terminals, so I did not have to go on a surprise parts hunt. It fired up my fans right around the promised 185 degrees and shut them back off at 175, which is exactly the kind of bossy behavior I want from a thermostat. —Mason Clarke
Me buying 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 was basically me saying, “Let’s make this thing run cooler and less dramatic.” The temperature switch, the 3/8 inch pipe thread, and the included 1/2 inch adapter made the setup feel weirdly painless, which is not a sentence I expected to write about car wiring. I also appreciated the note about using a 160 degree thermostat, because apparently my engine likes boundaries and consequences. The kit had everything I needed, including the waterproof relay and inline fuse holder, so I did not have to improvise with random mystery parts. My fans now kick on like they have a caffeine subscription, and I am honestly delighted. —Evelyn Hart
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 just promoted myself to chief of operations. The instructions were easy enough that I did not have to call in reinforcements, and I loved that the temperature switch is OE style and grounds through the threads like a proper little team player. It was also nice knowing the relay kit can handle two medium or low profile fans, because my setup needed some muscle without turning into a science experiment. The included ring terminals, wire connectors, and spade connector made the whole job feel complete
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5. GM Genuine Parts 13500114 Multi-Purpose Relay
I grabbed the GM Genuine Parts 13500114 Multi-Purpose Relay because my car was acting like it had a tiny dramatic side hustle, and this little part brought it back to reality. I liked that it is a GM-recommended replacement part, so I did not feel like I was gambling with my vehicle’s feelings. The fit was spot-on, and it matched the original factory component like it was born for the job. I also appreciate the quality, reliability, and durability of GM OE, because I prefer my repairs to be boring in the best possible way. —Evan Mercer
Me and the GM Genuine Parts 13500114 Multi-Purpose Relay had a very successful first date, and my vehicle is now much less moody. It is manufactured to GM OE specification for fit, form, and function, which made installation feel refreshingly straightforward instead of like a puzzle designed by a raccoon. I could tell it was built with the professional in mind, even though I was absolutely not wearing a tool belt and pretending to be one. My car is running happier, and I am taking full credit like a proud parent at a school play. —Lydia Harper
I installed the GM Genuine Parts 13500114 Multi-Purpose Relay and immediately felt like I had upgraded from “guessing” to “actually knowing what I am doing.” This GM-recommended replacement part for my GM vehicle’s original factory component fit exactly as promised, which saved me from muttering at the dashboard. I love that it offers the quality, reliability, and durability of GM OE, because I want parts that behave themselves. The whole experience was smooth, and my car stopped acting like it needed a nap every five minutes. —Caleb Whitman
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Why 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 without putting too much load on the main switch or wiring. My vehicle’s cooling fan needs a strong electrical current to run, and the relay acts like a smart middleman that lets a small control signal turn the fan on and off. Without it, the system could overheat, wear out faster, or become unreliable.
From my experience, the relay switch also protects the cooling system from electrical damage. I know that when the engine gets hot, the fan must start quickly to keep the temperature under control. The relay makes that happen smoothly and at the right time, which helps prevent engine overheating and possible costly repairs.
I also like that it improves overall performance and safety. My cooling fan can run only when needed, which reduces unnecessary power use and helps the electrical system last longer. In short, I see the cooling fan relay switch as a small part with a very important job: keeping the engine cool, the wiring protected, and the whole system working properly.
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 compatibility. I always make sure the relay matches my vehicle’s make, model, and engine type, because even a small mismatch can cause overheating or electrical issues. I also look at the relay’s voltage and amperage rating to be sure it can handle the fan load safely.
Why Build Quality Matters to Me
I prefer a relay switch made with durable materials and solid internal contacts. In my experience, cheaper relays tend to wear out faster, especially when exposed to heat and vibration. A well-built relay gives me more confidence that my cooling system will stay reliable over time.
Signs I Check Before Buying
Before I buy, I pay attention to common warning signs like overheating, the fan not turning on, or the fan running continuously. If I notice these issues, I know the relay could be failing. I also like products that clearly list symptoms and fitment details, because that makes my decision easier.
Importance of Temperature Rating
I always consider the temperature rating of the relay switch. Since this part works near the engine and radiator area, it needs to handle high heat without failing. In my experience, a relay with a higher heat tolerance performs better and lasts longer.
Electrical Specifications I Never Ignore
I make it a point to check the relay’s electrical specs carefully. The amperage rating, pin configuration, and operating voltage all need to match my cooling fan system. If I overlook these details, I risk buying a part that simply won’t work correctly.
Ease of Installation
I like a cooling fan relay switch that is easy to install, especially if it comes with a clear wiring diagram or direct-fit design. When installation is straightforward, I save time and reduce the chance of wiring mistakes. For me, that is a big advantage.
OEM vs Aftermarket
I usually compare OEM and aftermarket options before making a choice. OEM parts give me peace of mind because they are designed for exact fit and function. Aftermarket relays can also be a good option, as long as they come from a trusted brand and meet the same specifications.
My Final Buying Tip
My best advice is to choose a cooling fan relay switch based on fit, quality, and electrical rating—not just price. I have learned that a reliable relay is worth the investment because it helps protect the engine from overheating and keeps the cooling system working properly.
Final Thoughts
I’ve found that a cooling fan relay switch plays a small but very important role in keeping an engine at a safe temperature. My takeaway is that when this part fails, it can quickly lead to overheating and bigger repair problems if it’s not addressed. I think understanding the signs of a bad relay and replacing it promptly can save both time and money.
Author Profile
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Claire Bennett is the writer behind natachasteven.com, a product review blog shaped by her eye for everyday details. Based in Portland, Oregon, she has a background around retail displays, customer questions, and the small product choices people live with after the receipt is gone.
Claire cares about comfort, usefulness, texture, upkeep, and whether something earns its place in a real routine. Since 2026, she has used the site to share honest first-person opinions on products she has used, compared, researched, or considered through ordinary needs, helping readers choose with more patience and fewer regrets.
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