i realized my fans were not turning on so i saw this plug loose and it does not seem to fit where the fan switch would go. I am using a 2004 radiator on my ap1 can this be the reason because people told me everything from 00-05 is interchangeable on the radiator and the switches for the fan motor fitted but not this one.

 

Yes it is.

 

That is strange that plug should plug into the fan switch without any problems. This is true of not only AP1 to AP2 but more than just the S2000 use the same switch sensor, in fact a Mugen fan switch works for the following cars
Civic (1992-1995)
Civic (1996-2000)
Civic (2001-2005) Si
Del Sol (1993-1997)
RSX Type S (02-04)
S2000 (2000-2003)
S2000 (2004-2008) 2004-2005 Only
TSX (2004-2008)
Integra (1994-2001)
RSX Base (02-07)
RSX Type S (05-07)

There is a difference between the 06+ fan switches as they changed the size of the threaded side of the sensor but the plug should still be the same. That is why the list above states the 2004-2005 only. It is a little tricky to hook up since you are doing it by feel only and the key way is not very defined. Give it a try again and make sure it is engaging all the way. If it does not go on maybe the connector end of the switch is damaged. If that is the case do you still have your original setup, if you do just take the orginal fan switch and install it into the AP2 setup. Now if you do this and find that your AP1 switch does not fit then you were not sold a 05-05 AP2 radiator, like I said above they have different sized switches. Also do you have a real temp gauge to tell the acutal temperature? As the fans don't come on until about 200ish, so maybe the temp outside is cool enough that the fans are not needing to come on.

I remember you asking about the AP2 radiator setup working in an AP1 and I told you that it did. And from all that I have seen and worked on it should. I have worked on other AP1 S2000 and installed after market radiators and fans so this should work.

 

this is the radiator i have on now and the fan switch is on the bottom right the lil broze piece thats sticking out. My old radiator was thrown out so im mad and also can i get that piece from the dealer since im tr]ying to make it fit but its not working

 

Yes you can get it from the dealer here is the part number as listed with Honda

37760-P00-004

It should come with a new rubber o-ring as it is listed this way in the parts manual. But in case it doesn't here is the O-ring part number

91307-PN3-000