2010 Dodge Grand Caravan. Approx 65 Fahrenheit outside.

Parked in my driveway, I can run the Caravan until it reaches what appears normal operating temp on the dash temp gauge (midway point). The radiator fan does not turn on. Yet car does not overheat. What?! Shouldn't the engine overheat with no fan running?

Full details:
1) Son called me last night saying "car on fire".
2) Ended up being coolant leak. I could not find the coolant leak in the dark.
3) I waited for engine to cool, filled with some water, and drove it a few miles home. (Did not overheat per dash gauge.)
4) Upon reaching home, lots of coolant smoke coming from engine bay.
5) Popped hood but again in dark with engine all wet and smoke everywhere, could not locate source of leak.
6) This morning broad daylight, filled radiator and running engine, no leak, and no fan running, and no overheating. IS THIS CAR DEMON POSSESSED?

Thanks for any advice about this bizarre coolant leak/non-leak and engine that can apparently run without a radiator fan.

 

fyi - I found the coolant leak. There is a plastic Y pipe (located on the side of engine facing firewall) that is failing. Looks like a seam in the plastic pipe is failing, allowing a small but significant stream of water to shoot out.

Also regarding the radiator fan, I confirmed it is operational, by switching on the air conditioning, which forced the fan to run.

I still need to determine if the radiator fan will ever run without the air conditioning on. Maybe I need to let the engine idle more than 10 minutes, or drive it around before the radiator fan will run?

 

may vary depending on the build
the 3.3L will turn the fan on at 104*C coolant temp or 96*c trans fluid temp or 250psi refrigerant pressure.

 

250PSI will rupture a steel cylinder I use in my lab (I develop aerosols) let alone a rubber hose:-) Do you mean 25PSI?

To the original post, if you turn your A/C controls to the on position the fan will be turned on regardless of temperature, you can use that to test if it is turning at all. That wouldn't help you to troubleshoot whether or not the fan was coming on at the appropriate temp. That said if you don't have pressure in the system (i.e. a leak anywhere) then the coolant/water mix will boil and might not set off the sensor that turns on the fan because liquid conducts more heat than the steam so the sensor might not know that you are overheating. So after you fixed the leak did the fan work okay?

 

the information I posted is right out of the fsm.

the high pressure side can handle a lot more than that...the high pressure cut off for this system is 447psi and the high pressure relief valve is 400psi. The numbers seem backwards to me as the system should shut off the compressor before the pressure relief should open.

This valve will blow off before a component does. The high side pressure could get to 400 psi in seconds on a hot day if the fan wasn't working and no air was moving thru the condenser. Put manifold gauges on it, unplug the fan and start the a.c system...watch how fast it shuts down...and nothing blows out.

are you referring to crimped aerosol cans?

 

I'm talking about the water coolant system, like the radiator and such because that's where the coolant temperature sensor is. I think we crossed a wire here somewhere in this conversation:-)

 

Okay, I see you said refrigerant. I missed that completely. Sorry.

I usually come to this form when I'm on break and I'm stretched pretty thin mentally. I do aerosol research and development and it's a real pain in the ***....well head, most days.

 

It’s not uncommon for there to be more than one relay for controlling the fan. Usually they’re related to fan speeds, but sometimes it’s also related to which module is controlling it.

I don’t have a wiring diagram to look at, but it’s possible one of the relays or control circuits is bad and the other is good which is why it’s working for ac but not sitting at idle.

 

or maybe the coolant isn't getting up to 104*C

 

I finished replacing the OEM plastic heater hose Y pipe, using an aftermarket aluminum version. I refilled the radiator and the vehicle runs again without radiator leakage. As mentioned, if I turn on the air conditioning, then the radiator fan runs, else it doesn't. Or at least, it doesn't run when in park with the vehicle standing still, even when engine has reached normal operating temp via the dash gauge.

I drove around, parked and quickly popped the hood, but engine fan was not running. No overheating, gauge always reads normal. Odd.

Maybe this van has a very efficient cooling system, and only needs to have the fan running when the vehicle is moving or under load? I've never had a vehicle like that, but it's my best guess. If there really were a fan issue, then I assume the dash gauge would read hot, and the engine would overheat. I guess I will have to keep an eye on it and see how things go.