Travis Jones

12 JK 3.6L has an odd problem, the auxiliary fan is running much more than normal. It hasn't overheated yet... Coolant level is good. Everything seems normal...I did have an odd heat thing going on at the end of winter. It would start blowing cold if you say or ran low rpms then when you get back in the gas it would blow hot again....do I need a water pump or could it be something else?

OCHO BACON

The 3.6 engine had an issue with sand casting problems (can't remember exactly which year or years were involved) , there was sand clogging up heater cores and radiators .
Someone that experienced it may chime in , or you could search for 3.6 sand cast head issues your self . I do remember it being a problem on some threads here in the past . good luck .

HostileJK

If your low on coolant or have a big air bubble it will have those symptoms, but it can also have those same symptoms if the impeller is coming apart and not circulating water well enough.

Rednroll

Yep, those are typical symptoms for having low coolant. You should start by filling your radiator with coolant. It helps to jack your passenger side up from under the axle so the mouth of your radiator is at the highest point. Then with the engine running fill the radiator and then continuously squeeze your upper radiator hose to force out any air trapped in the hose, while continuing to fill the radiator. Once that is complete, then fill your overflow to the max fill line.

Things should go back to working normal after that, but then you may have to determine what caused your coolant to be low in the first place. This typically needs a coolant system pressure tester. The most common source of leaks are the radiator and the thermostat housing in the 2012+ JKs.

Likely not the water pump unless you notice leaking from around the water pump and/or hear abnormal noises coming from that water pump.

resharp001

Do you have access to monitor your engine temps via the factory computer or an aftermarket device? Summer time in South Carolina......the engine probably going to run warmer than normal and hence the fan is going to be on more often. That's not to say you don't have an issue, but I'd start tracking coolant temps so you have a baseline of data to go by.