Hello All,
First time here so please forgive me if this has been posted before. I have a 2013 Durango R/T 5.7 Hemi. The rad fan will only function on low with the AC on. The coolant temp fluctuates, as expected, while driving. I have done some trouble shooting (Temp sensor, thermostat , fuses and fan motor all working). I checked the low speed fan relay in the TIPM and it appears to be working (checked with voltmeter). Just in case replaced the relay. I also was able to jump this relay and have the fan spin on high. My question is I have read that there is a "High Speed Relay" for the fan. I have looked high and low but can not find the relay. Can someone please help and let me know where this mysterious relay is hiding. Much appreciated.

 

In the factory wiring diagrams I only see references to the low speed cooling fan and associated relay. I looked in both the engine cooling fan circuit section and the HVAC section. But what's interesting from the wiring diagrams is it doesn't appear the relay does anything. The outputs from the relay appear to both be "Not Used." Instead there's a Radiator Cooling Fan Module located to the backside of the radiator and that appears to control the fan speed.

-Rod