[encantotom]

this one will be interesting to troubleshoot. i am not close to my coach right now, but i seen to remember there is a temp sensor at the bottom of the radiator on the side near the rear of the coach. i dont remember if it is for the ddec, the fan or maybe both. does anyone know if the ddec puts out that signal to turn it on or not?

i think if i remember right that the relay turns it on for low, but rather it turns it on high when the call for extra cooling comes from some sensor. the way i tested to see if the high speed comes on the fan is to just disconnect the relay when it is running and on low. so i am not sure if that relay has anything to do with the low speed turn on.

i suspect there is 12v to turn the fan on when the engine is on. then the relay kicks it up to high when it gets on mine a little over 200 degrees. that takes it quickly down to below 200.

so i hope this sparks some thoughts on the issue and where that 12v to turn the fan on comes from and if i am all wet or not.

come on brainy ones, lets help him

tom