My engine overheats when I use the air conditioner. The shadetree mechanic is reading a low fan relay, but cannot find it. Where is the low fan relay?
low fan relay causing engine to overheat when using AC on 2003 Dodge Ram 3500
There is an air conditioning condenser fan relay on other Ram's excluding the diesel 8.0 L. The relay is in the integrated power control module in the engine compartment (sorry I cant say exactly where). Fuse 12 protects the circuit (30 Amp) The wires at the relay should be dark blue/yellow, red, and two wires that are red/black.
I successfully re-wired a non-functioning low fan circuit in my 95 Taurus to operate from a switch I installed on my dash. I used a Fuse holder W/fuse, a switch, and a relay to build this circuit and connected it to the low fan connections on the fan itself. The high speed fan circuit still works fine. Ford houses the low and high fan relay in a larger module usually under the VEC label(vehicle emmisions certification) which is over the radiator. The low speed relay in this module doesn't work but the high speed relay still does and as this part is over $100, I like my under $20 solution better. I have had no problems with the low fan since installing the fan switch, relay and fuse. I chose a lighted switch and wired it to light up only when the fan is on so I wouldn't forget to turn the fan on, which is the only disadvantage(you can't forget to turn it on or else car runs hot or worse it could overheat). I've been successfully using the car like this for 4 years, no overheats due to still funtioning high speed fan circuit, but car will run warm if I forget to turn it on. In your case, if the low fan relay is a single piece and not a part of a larger module, it may be better to just replace it. Your local library(i.e. Reference section auto manuals, or on the computer-->Alldata or Mitchell-on-Demand which are repair databases) and Dodge will have the information on the component location and should provide this free of charge(at least @ the library it'll be free or just the cost of copies) Good Luck
where is the low fan relay