Temperature gage goes to HOT

Temperature gage goes up to HOT when I turn on the AC but when I turn off the AC, the temp goes back down. I drained and flushed the radiator and I replaced the thermostat but when I turned on the engine again and it warmed up and the AC was turned back on, the temp went back up to HOT. Whats next? I noticed the sound of boiling water in the upper hose but the radiator cap and the radiator water were not hot; I stuck my finger in it.

 

hmm weird... never heard of it, hopefully someone can help you out.


welcome to tw by the way!

 

Are you sure your engine is cycling coolant through the radiator? That boiling noise and a cool radiator is good sign something's not working as it should.

 

take off the radiator cap when its cold. start it, watch the coolant and the gage. if the gage gets hot and theres no movement in the coolant its not cycling

 

Water pump?

 

I hate it when my gage goes hot

 

Thanks, I am going out right now and doing as you suggest; I'll let you know what happens...

 

I took off the cap and watched the water/coolant; it does not move but it does get hot. Also the upper hose gets so hot you can't touch it. What do you think? Water pump or radiator or fan clutch?

 

When the engine is running and you turn on the AC, do the RPMs inscrease by 100 or so when the compressor kicks on? If not, could be a sensor or switch or relay that is faulty and not revving up the engine for additional cooling when the compressor is running.

I don't think this alone would cause your temp to max out, but it could be a factor in your problem here.

 

Scott, is that what the temp sensor does? I'm trying to find out all of this so I will be more educated about what the real problem and costs are when I take it in to a mechanic. The small things I can do myself but when we get into motors and such, I'll have to hand it over.