so i figured out the problem with my a/c and it ended up being a bad fuse for the clutch, now my question is my truck is running hot when i'm cranking the a/c.\



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Does the temp drop when you turn off the a/c?

 

Flush the cooling system REALLY well.

 

Yep. Either get some coolant flush or use a diluted mixture of CLR.

 

what causes this to happen? do i have a bubble or something? and yes, if i turn the a/c off full blast to about the second click it usually drops down a little bit

 

Fan speed shouldn't matter..... as the system is still operating the same way, whether the fan is on high, or low.....

Might be an air bubble, more likely, I think, is the radiator is just getting partially clogged with normal deposits.... clean those out, so the radiator works the way it is supposed to, and you should see lower temps. Running a bit warmer than normal with a/c on is pretty standard.

 

The cooling system should be flushed every three years. No way is there an air bubble in the system, plus that temperature display is "more than a bit warmer" with the A/C on.

 

well the coolant is fine, i just replaced the water pump and the small hose going to the intake about a month and a half ago or so, so it has fresh coolant in it, but i will go ahead this weekend and flush out the system and put new coolant in

 

assuming your truck runs at 195 when AC is not on....

i would guess your radiator is about half stopped up, and the extra heat from the AC condensor is overloading its cooling capability.

you can test this theory some by feeling the top and bottom radiator hoses. top hose will be hot as hell, as hot as the gauge. bottom hose should be cool enough, or almost cool enough to touch, maybe 120-130ish. if the bottom hose is hot, then the radiator ain't getting it.

another possibility is the fan clutch. if you spin it, it should be sort of semi-sticky and hard to turn, and not free wheel. if it spins easily and free wheels, then its bad and its slipping and not pulling air through the rad at idle.

a flush won't hurt, but probably won't help either. if you do flush it, remove your block drain plugs, hiding behind the engine mount on each side. you'll likely get some ugly deposits, but it still won't help.

 

On a clogged radiator, the bottom rad hose can be cool to the touch as well due to the slow flow of coolant through the rad. It just doesn't flow enough of that cooled coolant.

Things to consider:
1. Thermostat - If it's sticking closed, obviously a problem. Haven't seen this before but it's possible I guess.

2. Fan clutch - Can be deceiving. Drive down the road at 45+ mph, and if you still are running THAT hot while moving, it isn't the fan clutch. If your engine cools down while going 45+ mph, and then it gets hot when you slow down for a stop light, then there's a good chance it's the fan clutch or a clogged radiator. Keep in mind, the fan clutch relies on hot air coming off of the radiator for it to engage. If the radiator is plugged, the fan clutch doesn't receive the hot air it needs to engage...

3. Clogged radiator - stick a garden hose in the fill hole, if it only trickles out of the other side (unplug the lower rad hose) then the rad is most likely clogged. If it's plugged, I'd flush the system really good with the old radiator, and then replace the radiator. The goal here is to dislodge as much crap from the motor now so it can't clog up the new radiator.

4. Air bubble in the coolant system. Did it ever overheat like this before you changed the water pump, etc?

5. Radiator cap - If it doesn't build proper pressure, your coolant system can do some wonky things.

Good luck!

-JT