Is My Fan Controller About to Die?

[ZephyrEFI]

So, I went to start my car to pull into the garage after going for a drive and then leaving it out. The engine was still hot. I listened for the fuel pump to prime, but also heard this other loud buzzing noise. It turned out to be my fan controller. It makes a loud buzzing just before turning the fan on. I don't remember it doing that before. Does that mean it's about to die? It's a Torqflo 733647.

[84GT350CONV]

Is the noise coming from the fan itself or the switch in the dash?

[ZephyrEFI]

Is the noise coming from the fan itself or the switch in the dash?

It's coming from the controller. I probably should have mentioned I'm talking about my engine electric cooling fan. I don't control it manually, I have a controller under the hood that turns it on at a certain temp.

[84GT350CONV]

I'd double check your electrical connections first. It may not be getting enough current causing the buzzing noise before it activates. If not i would suspect the comtroller itself.

[ZephyrEFI]

Yeah, i'll check the connections. I just redid a bunch of them in the past year because I moved the controller, so they SHOULD be good. And the controller itself is only a few years old. It has maybe less than 2000 miles on it. I did spill hot coolant on it this year though. You might remember the fuse-melting incident.

[86GreenStang]

Ok I hate these fan controller problems; However, there is a simple fix and it is from Volvo (BMW also). Yuck did I just say that and how do I get that foul taste out of my mouth, yes I did. Volvo makes a dual output temp sensor. To use it you must make bushing in standard size on the outside and metric on the inside so the volvo temp sensor can be used. As the sensor reaches the lower temp position one grounds out then position grounds out at the next temp setting. This works great for me because I run a dual fan from 2000 cougar. When the position one grounds on the temp sensor it passes the ground to the switch ground on a relay which passes power to the fan through a 10 gauge wire. The 10 gauge power wire is overkill with 2000 cougar fan because each fan only draws 12 amps to start and 8 amps while running. Then when the second temp is reached the process is repeated through another relay for the second fan. This set up works great for a dual fan and would work fine for single fans using two positive power wires. The dual fan set up this way works so well that one day I was sitting in 97 degree heat behind a traffic jam and I noticed that the second fan cycling off to keep my car at my desired 190 temp. It also leaves the fans running about one to two minutes after the engine is off. No expensive controller, no massive mounds of wiring to have to trouble shoot if a problem does happen, and best of all no goofy probes to push into my radiator.

[ZephyrEFI]

That's a good tip!

In my case though, the problem was probably twofold. One, spilling coolant on the controller probably got the connections corroded, and probably did other damage as well. And two, it only had a 30 amp relay. My fan actually needs a 70 amp relay. It was a pretty warm day when I had the problem too. Frankly, I'm surprised that controller lasted as long as it did.

The Volvo controller isn't ideal for me because my car is EFI, so it needs the ECT it comes with. I could drill a new hole for a temp sensor, but I didn't want to do that. I went with a controller that uses my stock gauge (SWEET!).

[Ethyl Cat]

Ok I hate these fan controller problems; However, there is a simple fix and it is from Volvo (BMW also). Yuck did I just say that and how do I get that foul taste out of my mouth, yes I did. Volvo makes a dual output temp sensor. To use it you must make bushing in standard size on the outside and metric on the inside so the volvo temp sensor can be used. As the sensor reaches the lower temp position one grounds out then position grounds out at the next temp setting. This works great for me because I run a dual fan from 2000 cougar. When the position one grounds on the temp sensor it passes the ground to the switch ground on a relay which passes power to the fan through a 10 gauge wire. The 10 gauge power wire is overkill with 2000 cougar fan because each fan only draws 12 amps to start and 8 amps while running. Then when the second temp is reached the process is repeated through another relay for the second fan. This set up works great for a dual fan and would work fine for single fans using two positive power wires. The dual fan set up this way works so well that one day I was sitting in 97 degree heat behind a traffic jam and I noticed that the second fan cycling off to keep my car at my desired 190 temp. It also leaves the fans running about one to two minutes after the engine is off. No expensive controller, no massive mounds of wiring to have to trouble shoot if a problem does happen, and best of all no goofy probes to push into my radiator.

Hmmmm, this post sounds familiar.......