What color spark CTO switch do I need?

I need a spark cto switch and the parts store says there is a yellow, white and green one available and that all are different. What makes them different and which one do I need? This is the one that goes in the thermostat housing. Thanks in advance.

 

Spark is 3-port, SMP says ... green. White is two port -> EGR.

Not much impressed with your parts store :toetap:

http://www.smpcorp.com/web_app/catalog/publiccatalog.asp

 

Thanks Tim. I'm not either but if I know what I'm looking for, they can get the part cheaper than most other places.

 

One difference would be the temperature it opens at.

 

I didn't know what the heck a CTO was. I found a good 'splainin on the web:http://www.drbob.tqhosting.com/tech/cto.html

 

SwampRatt, thanks for posting that link. Great info!