On Monday, July 16, 2012 3:35:39 PM UTC-5, (unknown) wrote:
AC on, it only does this in the summer months. Thermostat is new. Any ideas on
what else to check?
Radiator fan works fine, coolant levels are fine, no obstructions in radiator
(new one installed about two years ago.) and no head gasket leaks. This only
happens when it is hot outside 90+ and the a/c is on and i am idle.
Just a possibility - check engine rpm when you're idling with ac on....as
opposed to ac off...Could be that the engine isn't turning the water pump
fast enough to circulate a sufficient volume of coolant to keep the temp
I have a similar problem with a Subaru 2.5L. Only after the engine has run
for more than half an hour and then left to idle for a short while. Temp
drops once on the road again. Replaced thermostat, no real change.
Radiator is full, no signs of leakage though maybe I am not looking in the
Is the fan running properly? Not sure if you have 2 fans or a 2
speed fan, but with AC on there should be a fan running constantly,
while with AC off the fan should cycle with temperature. On the run
you get enough air speed to cool without the fan on all but the
hottest days so it generally doesn't overheat until you slow down.
Double checked again, I have two fans, one not on the radiator, running the whole time, one on the radiator comes on after getting to normal operating temp. I don't know what it could be, inline cooling sensor? Since it only happens when ac is on that has to limit it to only a few things right?
I have a 2000 Forester 2.5 that is doing that. It's been diagnosed as a
problem with the A/C fan. It is sporadic, one time runs as it should then
doesn't run at all and runs hot. I have to use the heater to drive
normally. I have a new fan on order and hopefully that will solve it.
Not sure about the OP who had the Civic, but the temperature of the upper
and lower tanks of the radiator on my Subaru differed dramatically while the
car was idling. Near 200 Fahrenheit at the top of the radiator and 95
degrees at the bottom. Measured with an IR thermometer with the engine and
fans off. Yet the dash gauge showed overheating.
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