Not Jeep But is Chrysler... Overcooling

kejobe

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Not KJ related but still looking for opinions/options. Please move if there's a better place for this.

2008 Ram 1500 SLT 5.7L 4WD

Past week the truck has been overcooling. Thought thermostat was stuck open so replaced it on Saturday. Same issue. Replaced the temp sensor today even though my scanner was giving correct readout of the temp. Still overcooling/not getting to full temp, or taking A LOT longer than normal to reach full temp.

I did notice that the AC fan is running constantly with the selector in defrost. Switch to vent and it will shut off. Turn blower fan/system to off and fan will stop. Problem is I always keep the selector in the defrost/foot position.

This whole time the temp selector is in the hot position. AC button is off.

With this said, I was thinking the TIPM connections could be corroded causing the fan to constantly run. With it running, I'm thinking it's pulling cold air in across the motor and cooling the motor itself. I cleaned them with contact cleaner and put some dielectric grease on. Issue continues.

I'm thinking the TIPM is bad somewhere or something is going on with it.

Anything I may be missing? I unplugged the AC fan for now. Haven't ran truck yet to see if it helps.
 

tommudd

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Well on KJs the AC runs when on defrost all the time
not sure if it is the same on Rams or not
I have one ) Ram ) coming in next week for some work, but not helpful today
Sorry
 

kejobe

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The compressor will cycle as normal. It's just the electric fan for the condenser is running constant. There is a clutch fan for the motor/coolant which in all aspects appears normal and good.
 

Jeremy-WI

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Pull the A/C relay, I did it for a few years because I wanted hot air for defrost when it was below 0F, but it is good to circulate the freon even in cold weather to keep the seals good. I also installed a remote start on my 2006 3 years ago so it was warmed up good
 

kejobe

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No relays that I can find. All built into the TIPM (Totally Integrated Power Module).
 

LibertyTC

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Have to bleed the air out of system, for it to pressurize properly.
If air is entering system that could mean a tiny leak somewhere.
Pressure testing the system is recommend to ensure it actually holds pressure.
 

kejobe

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No leaks. Holds pressure.

All this is why I'm essentially at a loss. The AC fan running constantly and pulling cold air across the motor is the only thing that seems to make any sense right now. But it running constant is the issue, or maybe another issue.

I've had the truck for 2 years now and this is the first I've noticed the constant fan running, and the first it's not getting to temp. Thinking 1+1=2. My math may be off on this though.
 

kejobe

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UPDATE:

Well, AC fan is not the problem. 50* this morning and still didn't get to operating temp.

The hunt continues.
 

duderz7

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Perhaps there's blockage in the cooling system and warm coolant is not reaching sensor? Maybe the temp guage itself is inaccurate, check temp with obd.
 

kejobe

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You're not the only one at a loss. Just removed the cooling fan and clutch and still with no fans at all to cool anything it still did not get to normal temp.

Thursday it was fine. Friday morning all this started.

Temp with OBD is 190*-196*. The truck is supposed to run at 203*.

Just warrantied the thermostat and boiled the new one before putting it in. Still same.
 

tommudd

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So it just started all of a sudden ?
Not once in a while, changing slowly over time ?
Thats one to make you throw your cap in the mud for sure
 

kejobe

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UPDATE:

Found Advanced Auto has the Carquest Premium thermostat. Same part number as a Stant. Same part??? I don't know.

Anyway, I got it, put it in.

Put new rad cap on also.

Hooked up scanner to read temp. Got to 212* then dropped. Expected that. After bleeding the system with the scanner still attached, it's running 194*ish.....still. No change. I can get temp to 204* with heat off and holding RPM's at 3500, then it'll drop to 200*-201*. Drop back to idle and temp back to 194*.

I'm at a complete 100% loss on this one.
 

kejobe

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Alright, last update unless something changes. I have Mopar radiator cap ordered. When it comes in, I'm throwing it on and calling it a day. I'm done chasing this.
 

JeepJeepster

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Im a little confused. You say its running 194F, then say youre at a loss. What am I missing? 194F is completely normal. Even if the tstat says 205F on it, the temps will vary depending on where the tstat is located (top of the engine on a hemi) and where the temp sensor is. Also, not everything is 100% accurate/precise.

Also, the defrost will run the A/C, which turns the cooling fan on. Thats normal operation.
 
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kejobe

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Im a little confused. You say its running 194F, then say youre at a loss. What am I missing? 194F is completely normal. Even if the tstat says 205F on it, the temps will vary depending on where the tstat is located (top of the engine on a hemi) and where the temp sensor is. Also, not everything is 100% accurate/precise.

Also, the defrost will run the A/C, which turns the cooling fan on. Thats normal operation.

The loss I'm at, is the temp needle was just barely touching the bottom of the center line on gauge for the past 2 years I've owned the truck, no matter the outside temp or length of run time. It would go just above, then settle just below when thermostat opened.

Overnight it decided to not even get to the center mark and settle at about 1/4 and was running about 190* per scanner. Went through all the above and now it still will not get to center and settles about 5/16-3/8 area at 195* per scanner.

Basically, it ran at 203* for 2 years and overnight it dropped to 190*. I got it to 195* now and can't get it back to what was normal for this truck. This is why I'm at a loss.
 

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