2005, 2500 Silverado Runs Hot Only When Ac Is On While On The Highway.

Nitsud84 · June 10, 2011

I live in Florida and it is now summer. I have noticed my truck is running hot, up around 210 if I let it, when I have the ac running and I'm doing 70 mph on the highway. Once I turn off the ac it will slowly cool down while even while maintaining the same speed. I was going to replace the thermostat, but before I do I was hoping someone could steer me in the right direction. I've looked through other forum discussions I just haven't seen anything exactly like this. Also this is with out pulling anything, just a truck. Thanks.

2010.6.2L · June 10, 2011

I live in Florida and it is now summer. I have noticed my truck is running hot, up around 210 if I let it, when I have the ac running and I'm doing 70 mph on the highway. Once I turn off the ac it will slowly cool down while even while maintaining the same speed. I was going to replace the thermostat, but before I do I was hoping someone could steer me in the right direction. I've looked through other forum discussions I just haven't seen anything exactly like this. Also this is with out pulling anything, just a truck. Thanks.

Can you hear the fan engaged? There is lots of talk about the lly's and changing out the mouth piece. I would look into http://www.alligatorperformance.com/466002...max-p-3991.html

lots of info about this on duramaxforum and dieselplace.

markw8 · June 15, 2011

210 isn't close to hot. My 08 is always on the 210 mark.

Mark

Nitsud84 · June 15, 2011

210 isn't close to hot. My 08 is always on the 210 mark.

Mark

I havehad the truck for about 4 years and have never had it get that warm before. I have read that they are designed to run between 180-210 degrees. If it maintained a temperature right now I wouldn't be as concerned, but I don't like how it fluctuates so much.

txab · June 15, 2011

I'd look into the fan clutch.

8100 Power · October 2, 2011

X2 on the fan clutch. Also, some 05's had overheating issues. I search the diesel forums and read more.

dmax3500 · November 12, 2011

wash out the cooling stack,how many miles on it?,over 100-150k you might need a new fan clutch

njkroeker · November 19, 2011

x2 on washing the cooling stack. If you do much off highway driving you could be plugged up

Dennis SS · February 2, 2012

Has the coolant bottle overflowed at all? Are you using up coolant? Does the temp guage flux erratically? Like one minute it will be cold and then then next second it will be at operating temp.