At the end of last summer had a issue with overheating when running the A/C. In the fall I flushed the system and added new fluid. Didn't have any issues. The last month I have had issues with the truck overheating again. It isn't every time but usually will happen with city style driving.

I took it into a shop, they put it on their tester, drove it, also put on the computer and nothing showed up. I asked them what the likely cause would be, since they couldn't get it to overheat they didn't want to just throw parts at it. I had them replace the thermostat anyway.

It worked fine for about a week with no issues and I ran the A/C constantly to try and get it hot, then it got hot. I checked the fluid and I added about half gallon? Had no other issues for the last several days.

Then yesterday took a 40 minute drive to Bass Pro. No issues going up. Coming back about 10 miles from home it started to overheat. I always found the reserve tank to be full and decided yesterday to go and get a new radiator cap. Thinking it was bad.

Today I drove it for about 40 minutes and then again it started to overheat.

I have had no leaks on the driveway or anything so I'm not sure whats up.

Any ideas or advice would be greatly appreciated.

Also, this is the 4.7 V8

 

is the ele fan working?

 

Not sure but maybe a bad water pump?