Gen 2 Coolant Temp and Fan Operation

[rgorke]

To start, my car is not overheating! All of the cooling system parts have been replaced at least twice over the life of the car.

My question relates to the functioning of the cooling fan, the A/C system, and cooling temp. I periodically connect my iPhone to the car through a Bluetooth OBD2. This allows me to do multiple things like check any codes that pop up, monitor fuel trims (if I get a lean code), and monitor coolant temp.

This morning, I was driving into a parking spot at work and connected my iPhone . As I was sitting in the spot, the coolant temp was 217. Since it is in the 50s here in SoCal, I did not have the A/C on. I turned on the A/C and watched the temp drop from 217 to 208 within a minute or so. I then turned off the A/C and watched the temp climb back to 215 in 30-40 seconds or so.

I do know that when the A/C is on, the fan engages to pull air through the condenser also pulling air through the radiator. A while back, when I was overheating due to a cracked degas bottle, the fan was going full bore.

Does anyone know at what coolant temperature the fan activates? I seem to recall there is a graduated fan activation based on temperature, could this be altered for the fan to come on at a lower temp? All of this stems from my dad's paranoia of cars overheating...I suppose the apple doesn't fall far from the tree. I would think that this is right up joegr's alley, but I haven't seen him around for a while.

 

[rgorke]

I may found the answer to my own question...

Google Search

 

[clubairth]

When posting question without any car details you just can't expect any answers?
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[rgorke]

When posting question without any car details you just can't expect any answers?
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Title says Gen 2…it’s a V8. I also said I found my answer.

 

[evergreen]

To start, my car is not overheating! All of the cooling system parts have been replaced at least twice over the life of the car.

My question relates to the functioning of the cooling fan, the A/C system, and cooling temp. I periodically connect my iPhone to the car through a Bluetooth OBD2. This allows me to do multiple things like check any codes that pop up, monitor fuel trims (if I get a lean code), and monitor coolant temp.

This morning, I was driving into a parking spot at work and connected my iPhone . As I was sitting in the spot, the coolant temp was 217. Since it is in the 50s here in SoCal, I did not have the A/C on. I turned on the A/C and watched the temp drop from 217 to 208 within a minute or so. I then turned off the A/C and watched the temp climb back to 215 in 30-40 seconds or so.

I do know that when the A/C is on, the fan engages to pull air through the condenser also pulling air through the radiator. A while back, when I was overheating due to a cracked degas bottle, the fan was going full bore.

Does anyone know at what coolant temperature the fan activates? I seem to recall there is a graduated fan activation based on temperature, could this be altered for the fan to come on at a lower temp? All of this stems from my dad's paranoia of cars overheating...I suppose the apple doesn't fall far from the tree. I would think that this is right up joegr's alley, but I haven't seen him around for a while.

Just got the 2003 3.9L back from the dealer last week. Had been flummoxed by rebuilding the cooling system and watching the temp walk all the way to 234F (iPhone with OBDLink plugged in). Gave the dealer the whole story and let it be known that there is a brand new aftermarket thermostat installed, and everything else was either max 4 yrs old or new (new degas, radiator, water pump, thermostat assy, gaskets, all else 4 yrs). And, no leaks. Dealer called after checking it out, and said it runs perfectly. Provided the measured thermostat opening temp and fan-on temp (can't find the slip at the moment, but they were something like 204 and 212 or some such). Told him to keep it and try to reproduce 230F. 60 miles later, car still acting perfectly. Picked it up, drove it without incident--but it never indicates on the temp gauge anything other than normal. Plugged the OBD in a couple days later, 226F according to the log saved, but recollection is that it went to 230s (there must have been a cycle when the temp was monitored but not logged). Never gave any indication other than the logger registered the temp.

Turning on the heater will drop the temp by about 10 degrees. That has been the fixit for the last few months before finally taking it to the dealer.

When buttoned up from last repair/replacement (water pump & radiator), after a dozen bleed cycles to MAKE SURE it took, it ran with no temp issue. Only after a stretch did it misbehave. So, oddly, it was bled into working condition and eventually worked its way out of ideal condition on its own (again, no leaks). Now, it seems to peak in the high 220's without boiling the coolant like it did previously.

???