Temp gauge peaks on 1993 dodge spirt
I have similar problem in that my rad cooling fan won't run when hooked up to temp sending unit. Sending unit works okay, displaying what seems like proper temps on inside gauge, rising & falling with engine temp. However, my fan does NOT turn on when wire unplugged from sending unit. Tested fan motor with 12v applied directly & it runs fine, so motor okay.
Haynes manual identified a faulty cooling fan relay (in a situation with your symptoms), which is mounted on the drivers side fender of the engine compartment with 1 other on a support bracket (2 others on same bracket if you have ABS), facing forward toward headlight (NOT nearby ones that are parallel to fender, which has 3 relays on a support bracket). This should work in your case, but didn't in mine.
Several of these close-together relays have the same # on them, so you could swap 2, to see if this is your problem, since normally 2 or 3 relays wouldn't fail at same time. To be sure, I bought a new generic relay of proper # from local auto parts store -- about $10-12 I think -- and installed it in the right place but fan still didn't work. Swapped the 2 relays next to each other (there are only 2 on my forward-facing bracket), both with same #, and still no go.
I'm TOTALLY STUMPED on mine, but yours should work with a functioning relay of proper #. Let me know how it goes.
If anyone has suggestions for my related problem, I'm all ears!
on Jun 21, 2014