Sorry, I can't search for this...so here goes.

My temperature gauge fluctuates, big time. It goes all the way up, and all the way down, sometimes stops in the middle, then finally rests on about 180 (The first mark on the gauge) It's not like the cars overheating when it goes all the way up or anything, and it wouldn't really be annoying me, except my heat only works when it's on that first mark. Anyway, when it finally does decide to go to that point, it stays there for a while, but will periodically become eratic again, causing my heat to blow cold. Any ideas what can do this? I'm guessing it's something simple like a sensor or something, but I don't know much so anything I say is just a guess. Any help would be appreciated. Thanks

 

The guage indication has nothing to do with whether or not it throws heat and since you say it blows cold intermittently then I suspect a cooling system issue. A common problem with the guage is the sender wire at the driver side bet cyls 1&3 droops on to the exhaust manifold and shorts to ground causing the guage to intermittently peg. However that will NOT affect the temp the engine is running at. You may have a sticky thermostat. Coolant temp sensor will not cause the problem you describe. CTS is different from the guage sender so don't confuse the two. Sounds like you need to go over the cooling system. A leak will cause pressure to go up and down. Don't overlook the radiator cap. Has the system been serviced, maybe it was not bled properly. Basic troubleshooting should reveal problem.