3.6L Radiator Fan Problem?

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SitKneelBend

SitKneelBend

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Thank you for the data logging offer. I will try to do as you have done and get the information for my vehicle.

I have cleaned the radiator and condenser. I cleaned them once before when I switched over to LED lighting with grill off. I cleaned them again when I deleted the AGS. Used the spray cleaner in a bug sprayer pump that I use for my home AC units. Spray on, it foams, wait ten minutes, rinse off type. The condenser looked pretty clean from the get go as I assume the AGS offers a degree of protection from excessive bug guts and debris.

Your data does dispel the belief that the e-fan is preset to switch on and off via a PCM program using only designated temperature points. As dynamic as you’ve found the system to be I wonder what other systems feed the PCM data. I remember reading some time ago a post in another thread that something in the AC system feeds info to the PCM for cooling commands. I dismissed it at the time and now can’t find the post.

I see your modified air tube. What is the goal of your experiment? Lower intake charge temps?
Air tube - essentially yes...keep the intake air as cool as possible. That is fiberglass wrap around it which I have since covered with the shiny foil duct tape and than wrapped that with black tape rated for engine bays.
 
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SitKneelBend

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Mine is the black plastic with plastic bleeder screw. I wonder if yours is OEM as I know Dorman offers an aluminum housing.
That was my thought too but I went through all of my service records and never saw a thermostat replacement listed? I also doubt that Chrysler would have gone from plastic to metal to plastic again in production of the 3.6L. I'm the original owner as well.
 

Atcer2018

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Air tube - essentially yes...keep the intake air as cool as possible. That is fiberglass wrap around it which I have since covered with the shiny foil duct tape and than wrapped that with black tape rated for engine bays.

What I assumed. Intake air temps do matter and a cooler charge is more efficient. I’ve supercharged a few mustangs and intake charge temps drive tuners crazy. I don’t write tunes but have had to modify intake tubes and it’s a PITA. Insulating your tube was a good idea. Gotta see how much heat it displaces and if it eventually holds the heat as under hood temps rise. Although not critical in a normally aspirated engine it could give you better gas mileage and little more power.
 

Atcer2018

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That was my thought too but I went through all of my service records and never saw a thermostat replacement listed? I also doubt that Chrysler would have gone from plastic to metal to plastic again in production of the 3.6L. I'm the original owner as well.

Well dang, I had no idea that Mopar ever had or used an aluminum housing. I have no complaints with the plastic housing although I’ve seen complaints about the plastic crossover tube connected to the housing. Is your crossover tube plastic or aluminum?
 
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SitKneelBend

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Well dang, I had no idea that Mopar ever had or used an aluminum housing. I have no complaints with the plastic housing although I’ve seen complaints about the plastic crossover tube connected to the housing. Is your crossover tube plastic or aluminum?
Checking that this week sometime when I put the intake on. To my knowledge MOPAR doesn't have a metal one and like I said every video I've seen of 3.6L teardowns has a plastic housing for the thermostat (and that crossover too). I'll let you know what I find and if I can get an angle I'll try to take a picture on part numbers.
 

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The PWM fan is also controlled by A/C line pressure buildup. On a cool day I can open the hood with the A/C on, and the fan will come on for a short time every few minutes. On a warm day it will come on sooner, stay on longer, and sometimes spin faster, according to ambient temperature.

I do wish I could change my pwm fan temps in without sending off my locked computer, then trying to program the settings.

There is no way it's good for an aluminum to go from 228 deg to 190 deg when dropping off the back side of a mountain.
 
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SitKneelBend

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The PWM fan is also controlled by A/C line pressure buildup. On a cool day I can open the hood with the A/C on, and the fan will come on for a short time every few minutes. On a warm day it will come on sooner, stay on longer, and sometimes spin faster, according to ambient temperature.

I do wish I could change my pwm fan temps in without sending off my locked computer, then trying to program the settings.

There is no way it's good for an aluminum to go from 228 deg to 190 deg when dropping off the back side of a mountain.
Agreed! I think what I found is that the unlocked PCMs don't come with new set points for the fan but rather the accompanying tuner allows you to add custom set points at at least 3 temperature settings based completely on coolant temperature. I honestly wonder if an unlocked PCM would be necessary "if" they would not give you all the other features and just provide a device that gives you 3 customizable fan points and speeds. Along those lines, I wonder if this Jeep controller would be plug and play on our Rams?


The fan itself shown for the Jeeps is identical to the Ram except the shroud housing is different.
 

Atcer2018

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Agreed! I think what I found is that the unlocked PCMs don't come with new set points for the fan but rather the accompanying tuner allows you to add custom set points at at least 3 temperature settings based completely on coolant temperature. I honestly wonder if an unlocked PCM would be necessary "if" they would not give you all the other features and just provide a device that gives you 3 customizable fan points and speeds. Along those lines, I wonder if this Jeep controller would be plug and play on our Rams?


The fan itself shown for the Jeeps is identical to the Ram except the shroud housing is different.

That fan controller was suggested by another member when I inquired about e-fan adjustments with AlfaOBD. Supposedly it works with Ram trucks.
 

Atcer2018

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The PWM fan is also controlled by A/C line pressure buildup. On a cool day I can open the hood with the A/C on, and the fan will come on for a short time every few minutes. On a warm day it will come on sooner, stay on longer, and sometimes spin faster, according to ambient temperature.

I do wish I could change my pwm fan temps in without sending off my locked computer, then trying to program the settings.

There is no way it's good for an aluminum to go from 228 deg to 190 deg when dropping off the back side of a mountain.

Yardbird do you know where I can find out more information about the AC line pressure and the operation of the 3.6 electric fan? My fan appears to be working as designed but I have an issue with temps climbing when doing 65-70+ on the interstate with the AC on. At 55-60mph no issues and the coolant temps fluctuate between 204-210. Over 65mph they start to climb, 70mph or above the temps go into the 220’s. If I slow down the coolant temps fall, turn AC off the temps fall. In town driving including stop and go traffic no issues with AC operation, only at higher speeds on highway. I’d like to learn more about AC line pressure.
 

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The controller shown only goes to 2018 in the Jeep. 2018 Rams ECM is locked, so no go for me. Dang it....

Either their years are wrong, or the Jeep had an unlocked ECM in 2018.
 

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Yardbird do you know where I can find out more information about the AC line pressure and the operation of the 3.6 electric fan? My fan appears to be working as designed but I have an issue with temps climbing when doing 65-70+ on the interstate with the AC on. At 55-60mph no issues and the coolant temps fluctuate between 204-210. Over 65mph they start to climb, 70mph or above the temps go into the 220’s. If I slow down the coolant temps fall, turn AC off the temps fall. In town driving including stop and go traffic no issues with AC operation, only at higher speeds on highway. I’d like to learn more about AC line pressure.
I don't know the line pressure settings or anything about the wiring.

I have thought about finding the pressure sensor for the A/C, and seeing if I can trick the fan into coming on sooner with a resistor in the voltage line. Used to do that on the fuel temperature sensors on Caterpillar truck engines.

Do you suppose you could be having a coolant circulation problem? I've read about sand castings being in the engines clogging up heater cores and radiators.
 
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SitKneelBend

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Yardbird do you know where I can find out more information about the AC line pressure and the operation of the 3.6 electric fan? My fan appears to be working as designed but I have an issue with temps climbing when doing 65-70+ on the interstate with the AC on. At 55-60mph no issues and the coolant temps fluctuate between 204-210. Over 65mph they start to climb, 70mph or above the temps go into the 220’s. If I slow down the coolant temps fall, turn AC off the temps fall. In town driving including stop and go traffic no issues with AC operation, only at higher speeds on highway. I’d like to learn more about AC line pressure.
You can view it and other A/C values with Alfa OBD. I did that too over the weekend. AlfaOBD for the win (again)...

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SitKneelBend

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The controller shown only goes to 2018 in the Jeep. 2018 Rams ECM is locked, so no go for me. Dang it....

Either their years are wrong, or the Jeep had an unlocked ECM in 2018.
Not necessarily, the Jeep years may not line up perfectly with RAM years. It may also reflect a change from the Gen2 to Gen3 3.6L after that or a change in fan type on later years (from what I see the Jeeps use two different PWM Fans for). From what I see on their wiring diagrams I'm thinking it will work but it is marketed towards Jeep owners. The ECM/PCM was locked on RAMs in 2015 but these do not have the accompanying tuner to make them function so I think it might work. If I understand the operation correctly, this thing sits on the CANBUS and reads the information it needs for what is happening in the truck (CANBUS signal for A/C on and/or Coolant Temperature), when either of these conditions are met, it sends out it's own signal to the fan to turn on based on it's internal settings and not what the ECM PCM says.

I see no requirements on their web page for an unlocked PCM so this might be the cheapest route.
 
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SitKneelBend

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I hope someone tries this and post their results. I don't want to be the test pilot.
I'd do it if I could find one used at a heckuva price...Now that I understand more about what is occurring I'm not worried about it enough to care (yet).
 

Atcer2018

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I don't know the line pressure settings or anything about the wiring.

I have thought about finding the pressure sensor for the A/C, and seeing if I can trick the fan into coming on sooner with a resistor in the voltage line. Used to do that on the fuel temperature sensors on Caterpillar truck engines.

Do you suppose you could be having a coolant circulation problem? I've read about sand castings being in the engines clogging up heater cores and radiators.

Hummm sand in the block and core? First I’m hearing about this. I changed the coolant at 78k miles when I replaced the oil filter housing. Lazy me didn’t pull the lower radiator hose and only used the radiator drain. No debris in anything that drained including 10 gallons of distilled water. Now I wish I would have used the lower hose. I’m positive I don’t have air in the system. My gearhead friend has a vacuum filler and we used that for the final fill.
 
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SitKneelBend

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Hummm sand in the block and core? First I’m hearing about this. I changed the coolant at 78k miles when I replaced the oil filter housing. Lazy me didn’t pull the lower radiator hose and only used the radiator drain. No debris in anything that drained including 10 gallons of distilled water. Now I wish I would have used the lower hose. I’m positive I don’t have air in the system. My gearhead friend has a vacuum filler and we used that for the final fill.
I didn't see sand until I back flushed the heater core. It seems the heater core trapped most of that stuff. You could probably get a lot out (if any is present) just by draining just the heater core. That way you don't have to drain the whole system again. I used my garden hose to do it but you want to be careful not to apply too much pressure to the core. The hoses come off really easy too.

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