My high temp/ electric fan often running problem ended up being a cheap POS aftermarket thermostat.
topic21280.html#top
Moderator: volvite
Why does the ECM look at refrigerant pressure? My refrigerant is running low and have been meaning to top it up, but I rarely use it except for defogging. Could low refrigerant cause the fan to run?VStar650CL wrote: ↑Thu Jun 30, 2022 4:04 pmThe FSM says the ECM is only looking at engine temp and refrigerant pressure, but a hot tranny will indirectly drive up the engine temp by way of the heat exchanger, which is in the outlet tank of the radiator just before the coolant reenters the block. Keep in mind that going from driving to stopped will always cause the coolant to "cook" for a few moments because the water pump is running slower and airflow is reduced, but the coolant in the block still has a large thermal load from producing power. Until all of it circulates through the radiator, the temp in the block will momentarily spike. That's all perfectly normal, but it will often cause the ECM to ramp up the fan(s).TooMuchControl wrote: ↑Thu Jun 30, 2022 2:42 pmI had my cooling fan running even after getting off the road on non-aggressive driving.
I'm wondering if you notice that your temperature might peak for a few seconds - and then go back to normal?
This happened to me, and I only saw it when stopped a drive-thru for coffee. It spikes for a couple of seconds, but the fan kicks on and runs for what seems a minimum amount of time.
I think something might be boosting the keep the transmission cool, not just the engine.
check your transmission oil, if this is an automatic. Makes sure it's in good shape at a good level.
check your coolant tank for anything that doesn't look normal.
After I changed the tx oil, never happened again.
I think the Tx oil temperature sensor will trigger the fan to come on, even when engine coolant temperature is normal or within range.
No, the ECM is only looking at overpressure on the refrigerant, not under. If the A/C has a good charge but the condenser isn't sufficiently cooling the high-side, the high-side refrigerant pressure shoots way up. The ECM interprets that as a loss of condenser airflow and activates the aux fan along with killing the compressor.
Thank you very much for doing that. It's hard to know for sure, but I'd say that's about what I'm getting on mine as well. Maybe that's just how they are set up. For what its worth i saw an r50 Pathfinder go by out of a parking lot today and the fan was howling on it too. I don't think I'm going to chase this one any further until theres a real reason to. Thanks vstar for the info as well!