Hayden Automotive 3652 Universal Add-On Preset Thermostatic Fan Control – NOT For Computer (ECM) Controlled Fan Systems

**Update after 1 day** After driving at highway speeds then coming to a long red light, the fan doesn’t kick on until above 200 now. Sometimes 201, sometimes 207. The probe in the radiator just isn’t the most accurate. It’s not the probe, but how it relies on contact with the radiator. Hopefully it works in summer heat or I’ll be replacing the probe with an adjustable switch. I’ve seen temps as high as 220 with my stock clutch fan in Florida heat, so as long as it keeps to this range, I guess I’m fine. Used this to replace my mechanical fan. The thermostat in my truck is rated for 195. It’s a backward design with the thermostat in the lower (cool side) radiator hose. I placed the probe ~3” below the upper hose as described in the directions. Even though the switch is preset to 185, my fan actually kicked on at 195 according to my OBD2 scanner. That worked out perfectly. The temp raised to 197 briefly, then dropped down to 192 which is when the fan kicked back off. Hopefully it doesn’t short cycle a lot, but I imagine in summer heat, it’ll be running nonstop regardless in combination with the AC on. I spliced into the 12v wire on my AC clutch and it kicks the fan on when the AC compressor is engaged. The included diode in the green wire is a nice feature. The only complaint I have is the crappy self tapping screw. I drilled out a hole 3/4 the diameter of the screw and it still wouldn’t bite. I end up just bolting the relay to the hole I drilled.

I got this for my 2005 Dodge Ram 1500 5.7 Hemi. I have 2 aftermarket radiators so I needed a thermostat to turn on the fans. I had installed previously a variable thermostat and that worked for about a year. SO I decided to try this one, it is not adjustable, and looks pretty sturdy, all the wires plug right into the relay. The thermostat looks replaceable as well, so if that goes bad, I can find a replacement. The wiring is pretty straight forward, if you have some skills with automotive or basic electronic skills, you can do this in your garage. So far, it works, I no longer have to baby-sit my temp gauge to make sure I'm not over-heating, turns itself on and off, and the wiring has wires for at least 2 fans, and both mine are working. There is also a 'over-ride' switch lead so you can manually turn on the fans. So far I'm pretty happy with this set up, time will tell if it will outlast the last one I had. Phoenix AZ heat will determine that.

The thermostat kit worked great and was easy to install on a 2001 Jeep Wrangler with an aftermarket radiator. The turn on temperature was supposed to be 185°F. But it turns on right at 215°F and turns off around 210. The ideal operating temperature for a Jeep Wrangler of my vintage is 210°F. It is just a bit over the ideal operating temperature for my Jeep but just barely. I will keep it. I really wanted to bring down the operating temperature of my beloved Jeep a bit. But perhaps that comes with its own problems anyway. The only reason for four verses five stars is the inaccurate temperature rating. But everything works great other than that and it was a very, very, simple install. All you need to know are your colours. Still working great after three months.

I can’t fault the seller for this product because this was something that was outside of their control. However I had a pretty bad misfortune my relays and my fuses melting out. Now mind you, it is a 12V system And yes mechanical parts break all the time. (Yes I’m still returning this) After wiring this up and running dual fans (10” and 12”) I noticed the fans stopped working. I checked the solder joints and continuity to the fan motors, no issues. (And yes I had the orientation of the props spinning correctly) The instructions say to hook up the green or trigger wire to the AC compressor, however I’ve come to terms that this might not be good, simply because if your AC compressor is kicking on and off at specific temperatures in frequently, it’s ultimately surging the relay. Honestly the more better way is to put a dedicated toggle switch. (And yes I also replaced most of the AC system) Simple bad luck. To those who left bad/negative reviews. This trigger wire might be the reason

Thermal control didn't work I sent it back 2 weeks ago and never received a refund. The whole system is garbage the wiring looks like it was engineered by a 4 year old. I am an engineer/machinist/welder/fabricator/mechanic and I did design a much better system while on a cigarette break written on a paper towel. I retired from a NASCAR race team in 2012 and started my own company and honestly products like this is what makes engineers/mechanics look bad. Anyone who knows anything about automotive wiring knows that you never switch the ACC power on a relay but instead the ground so if a wire grounds out near the switch it is not a big deal...

Reasonable price, easily replaceable thermocouple switch, good backup relay pre wired for quick change out to keep 2 engine cooling fans going, to save engine from overheating,in conjunction with 2 quality Hayden fans. Relay fan controller is excellent Hayden mfr.