I have an 05 Silverado with a 5.3, it seems to be running hot, most times the temp gauge stays right in middle I think it's around 205-210, but in traffic the needle starts to creep up, also after driving the sides of hood and tops of fenders (where hood meets fenders) is very warm to the touch and it smells hot. I let it idle for a good 5 minutes or so and fans didn't come on, so I tried turning on a/c like I read someplace and fans kicked on right away. Is this normal? Any ideas?

 

There are completely different circuits you are comparing. One circuit powers up fans at specified coolant temp.. The other powers up fans when A/C is turned, not matter what the coolant temp.. The only way to test for high coolant temp is measure it after your coolant temp gauge reaches it's normal position. Then use an infrared(IR) thermometer on the upper radiator hose as the truck is running at idle. Don't have one of these pricey tools ? Then use any high temp thermometer, look in your kitchen for a meat thermometer, get an oven mitt and place/lay it on the top of the hose. It won't give as accurate a reading as the IR, but will give a close approx.. It's obvious the fans are working just might be getting power through the high coolant temp circuit. Check connectors at fans to make sure no gunk is breaking connection. Hope this helps.

 

thanks for the help, im sure the entire cooling system could use a flush, new therm...was a ranch truck its whole life before i bought it. I was wondering if it was a bad relay or something in circuit