[blue55]

I've just installed aluminum radiator with Derale twin fans. When the temp comes up to engage the fans they flutter off & on until the sensor is hot enough to lock them on. I'm sure it's not doing the fan motors any good and one of the relays is getting hot while this is going on. Temp sensor is installed in drivers side head and gauge sensor is in manifold. It's a small block.

 

[Finally]

Sensor shouldn't do that, if it is the sensor. There should be a wide spread between the on temp and the off temp to prevent what you're describing, like 20 degree difference or more.

 

[onovakind67]

Why do my fans flutter?

Are you a rock star?

 

[Finally]

why Do My Fans Flutter?

Are You A Rock Star?

Lol

 

[Philip]

If a probe is being used try moving it to a different location. It may be possible that the air stream when the fans start is pulling some cool air across the the probe rapidly cooling it and causing the fluttering.

 

[blue55]

"Rock Star" funny guy! It's a thread in sensor located in the head on the drivers side, not a probe. The fans are wired together, no sequencer to bring them on separately.

 

[blue55]

I received a response from Derale and they said that with their twin fans, 2 sensors are needed (one for each realy they furnish). One sensor is a thread in and the 2nd is a probe type. I told the guy that Summit catalog should list sensors with their fans to make life easier. I just received UPS with new sensor. It reads "operates two fans max 25 amps combined". Their fans draw 25 amps each so it can only be used for 1 fan.

 

[onovakind67]

Can you put up a schematic of your wiring? A relay will flutter if the supply current isn't sufficient to operate it and the load at the same time. The fan draws max current when it is stopped, and the current gradually decreases as the fan comes up to speed. If the inrush current to the fan is more than your circuit can bear, the fan will just start to roll then the relay will drop out. When it drops out, the voltage goes back up, the relay pulls in again and the cycle repeats itself. As the fan gradually picks up speed, the load on the relay decreases and eventually the relay stops cycling.

 

[bdc1013]

I received a response from Derale and they said that with their twin fans, 2 sensors are needed (one for each realy they furnish). One sensor is a thread in and the 2nd is a probe type. I told the guy that Summit catalog should list sensors with their fans to make life easier. I just received UPS with new sensor. It reads "operates two fans max 25 amps combined". Their fans draw 25 amps each so it can only be used for 1 fan.

I just installed 2 derale fans from summit and got that same module from summit after. I only used one module. It works for both if you set it up correctly. I have a few pictures of my install ill post up in a bit.

they just want you to buy more of there stuff. Don't buy another one.... you'll be fine.

My setup is working perfectly. Ron (who you met at Tony's) is the one who wired all my stuff up. If you have any questions PM him saying i told you to. (bikeron)

 

[blue55]

Brian, thanks for the info. I'll PM Ron after I get a chance to look over what I've done. I've got a home show we're doing in Auburn this weekend so it'll be a week or so. Bob

 

[bdc1013]

few pictures of a my new fan setup

 

[OSCARS66MALIBU]

Lol

DITTO :beers:

Although they could be pretty butterflies!