Okay so I got The Taurus fan put in last week. Was not prepared for the amperage draw of the high speed setting. So, two rewires later and Im up and running pretty good now. still waiting on a thermostat to arrive (Warranty) to turn the low speed on. Right now its just ran through the key. Anyway, Its wired up right and works like a charm! Even the AC is colder than its ever been. Still not as cold as it needs to be, but its a lot better. Today it got to 90 and the truck actually ran under 210 everytime I drove it. I even let it idle in my drive way for about 10 minutes. The temperature still never went up above about 200. Higher than I want, but it has a 195 T stat so Its never gonna run lower than that until I put a 180 in it, which will be soon. Eventually, Once I have the money and time, I will have it wired like this:

two fan controllers
one for Low Speed
one for High Speed

Each controller has two inputs, one input has a diode in it for the AC to not backfeed power from the regular input.

Low Speed Controller Normal input: Thermostat controlled, 195
Low Speed Controller AC input: AC turn on wire in the fuse panel. hot anytime the AC is turned on, not just when the compressor is on.

High Speed Controller Normal input: Thermostat controlled, 210
High Speed Controller AC input: Compressor turn on wire

so that's that. need a little more money, and as always, time, and itll be done then.

Also, drilled and tapped a 3/8 NPT hole in the intake manifold for a temperature sending unit. Its in the pictures as well.

So heres some pics:

 

Do you have it setup so that the low speed shuts off when you power the high speed? I'm not sure if the taurus fan would care about that or not.

 

I don't have it set up that way... So far no issues though. I don't think itll matter. I hope not at least. I would like to run the low speed on the 87a pin of the relay and high on 87 so only one is powered at a time. One big problem.... My 70 amp relay doesn't have an 87a. That's what I would prefer though

 

Okay. It seemed better. But yesterday it went through a harder test. It was 90 outside and I had the truck idling with the ac on waiting for someone. It was fine for about 20 minutes. Then it climbed over 210 and I had to do the whole -turn ac off and turn heater on full blast and roll the windows down until it cooled down- then ac back on to cool me down. Did that 4 times in the next 15 minutes. So what i don't understand is why would it run cool for 20 minutes then all of the sudden, it starts trying to get hot?

Then, to make it worse. While driving home from work everything is fine because I'm on the highway (or so I think) and half a mile from my exit doing 70mph the temp starts to climb to 210. I live less than 3/4 mile off the highway and the truck gets to 230 as i pull in my driveway so I killed it immediately and popped the hood. Radiator hoses are still very stiff and pressurized like they should be. No coolant leaking anywhere. Radiator cap is doing it's job and not letting any coolant blow past it. Overflow tank is at a good safe level. Absolutely nothing seems out of the ordinary. It's almost like the thermostat just decided to stick shut and wouldn't reopen. Drove to work this morning-80° out- truck never overheated. Acted perfect all the way.

I have no idea what could be causing these problems. T stat is a mopar 195. Got my new electric temp sensor yesterday. So when I replace that I'm also gonna switch to a stant 180 T stat and maybe that'll help me

 

Well if you were on the highway doing 70 you certainly weren't having an airflow issue, so that more or less leaves a circulation issue. It's certainly not unheard of to have a new thermostat be bad.

 

Well I replaced the thermostat today. Stant 180 just like I said. I prefer it running a little cooler anyway. Got my new temp sensor installed as well so my fan actually comes on and cycles off as it should. So I put it to the test in my driveway. I let it Idle and watched the temps. The fan would turn on at 205 and turn off at 190. The fan cycled 4 times I think. That was about 20 minutes. So I decided to go drive it. I drove it around town only with ac off then ac on. Never overheated. I get back and park it and let it idle. The fan never shuts off. The truck sits at 210 the entire time. I shut the ac off, It drops to 205 and no lower. Idles at 205 for 10 minutes before I give up and kill it. So no overheating, that's a plus. But I don't know why the temp wont drop after its been running for a while. To me, theres no logical explanation for that

 

Is the fan running on high or low speed?

 

High speed with the ac compressor, but only low speed for thermostat controlled. I need to get another controller to run a thermostat controlled circuit for high speed.

 

Still having weird issues. One that has been overlooked is the heatsoak issue. I'll park the truck at 195 deg and come back 5-10 minutes later and its close to 250 deg. that's a terrifying number in my opinion. I understand the truck will heatsoak a little bit because theres no coolant flowing through the engine to dissipate the heat. That being said, I cant imagine anything more than a 15 degree difference is okay.

Anyway, did some tests today. Made sure the temp sensor wasnt just on the fritz. Took a temp gun and measured temps at the sensor. always about 3 deg cooler than what the sensor read. Pretty accurate I think. So I checked other areas. specifically radiator which is less than two years old. I shut my fan off manually to let the truck get pretty hot so I knew the thermostat wouldn't be closing on me. 220 deg then I manually turned my fan on High and measured temps and the top radiator hose (In) and my bottom (Out) and with temps at the top around 205 the bottom was 190. temps at the top dropped to 180 and temps at the bottom were 168.

So I worry about only having at most a 15 deg difference from my in to my out. shouldn't it be 30-40 deg cooler coming out the bottom hose? Ive gotta figure this out soon because its only gonna get hotter from here on out. I have a new radiator cap on its way. should be here I think Thursday. Apparently noone local carries Stant Radiator caps anymore. Just a bunch of housebrand junk.

So I'll have a new radiator cap to try. I don't know, maybe mines never releasing pressure and its building up heat because of that.

Im grasping at straws at this point.

 

I'd think the radiator should be close to the same temperature from top to bottom since it's crossflow. Not positive though.