Can I use a 5 pin relay in place of a 4 pin relay?

[brads70]

Just messing with my electric fans and I noticed the fan comes on as soon as I turn the key. It didn't always do that, it has a thermostat that turns it on when it gets to 180 ( its adjustable) Because it comes on right away ( before it heats up) I suspect the relay might have gone bad. I have a pile of new relays here in the garage  but they are 5 pin. Can I just plug it in and use it as is? The socket has the extra blade socket but I believe nothing is wired to it.  I plugged it in to see and the fan does not come on with the key? So that either means yes you can use it in place of a 4 pin and the relay I replaced ( 4 pin) was bad or..... no you can't swap a 5 pin in place of a 4 pin?

[dodj]

It really depends on the pin-out of the relay (what each pin is connected to). It is very possible that the fans don't start with 'key on' and will never run because the wiring does not match up with the relay you are installing. I would first check to see if your temp sensor for the relay is not shorted.
But look at the drawing that is likely on the side of your relays. It tells you what each pin is connected to. If the pins end up connecting to the same functions (coil power, no, or nc contact) then it will be fine. the extra pin will not matter.

[HP_Cuda]

You can almost always rig a 5 pin to do the work of a 4 pin but it may take some Mcgyvering.

[brads70]

Thanks guys electrical is not my strong point, I'll get a 4 pin to replace it with. Cheap enough....

[Chryco Psycho]

the 5 pin is fine , just plug it in & go , the extra pin in the middle is a reverse switch , always powered until the relay is powered then it will shut off power , 87 is switched power on , 87a is switched power off

[dodj]

Thanks guys electrical is not my strong point, I'll get a 4 pin to replace it with. Cheap enough....

You can disconnect the temp sensor and if the relay/fan does not pick up you need a sensor not a relay.

[brads70]

the 5 pin is fine , just plug it in & go , the extra pin in the middle is a reverse switch , always powered until the relay is powered then it will shut off power , 87 is switched power on , 87a is switched power off

    I just got home, had to go to a few places to find a 4 pin relay . Now I'm not sure if all 4 pins are the same? 
but after some google searching I find out the one I have will work.  I have this exact relay....
http://www.novitatech.com/?q=aftermarket/products/accessories-relays/rl44

The one I'm replacing is a QXVF4-3-12A
                                       NO40A/14VDC

I think I'm good as there is NO and NC (  open and closed) these are both open.