one03sierra

iTrader: (1)

dcc---dc controller.

http://www.dccontrol.com/

marc_w

When the fans turn on while idling, you can't hear them or see any draw on the charging system. You just feel a warm breeze inside the engine bay.

When the AC kicks on, the fans automatically go to 50 percent... and if any cooling is needed on top of that, it gets added on. Just plain old 50% is pretty easy to hear inside the truck... so I can only imagine what 60% is like EVERY time the engine needs to be cooled. I would personally get tired of it...

Yeah, the temp probe only measures the coolant downstream. Mine's located outside the fan area, near the passenger side composite tank on the radiator. So no air is really moving over the sensor...

Basically if the radiator isn't doing it's job on it's own, the sensor will pick up on the hotter coolant temps before they go back into the motor, and reactively fix the issue.

The FAL seems to be a proactive setup.

MacADaYear

Im tryn to understand where you put your sensor... how is it not hit with air? Its in the enginebay right? ... hmm...

Mine is outside the fan area too but the air dosent blow just where the fan area is.. its gets moved all over.

HAZE

delta current, got it. thought maybe it was an upgraded offering from flexalite. i've been involved in construction for 20 yrs, direct current is the first thing that pops in my head when i hear dc. dcc, dual climate control. anyway sounds good, anyone know how many amps the 282's draw ? i see theres a 35 and 60 amp version, what do i need ? thanks for the link. ps can i just order the box and use the vsc wiring ? saw that was offered in 35 amp.

marc_w

Yeah, it's hard to explain... The radiator is something like 34" wide... and the fan housing only seems to be only about 30-31" wide, so there is about a 1.5-2" gap of cooling fins on each side of the fan housing that don't get any air moving over them from the fans.

I was just trying to say that the temp sensor isn't mounted directly in front of a fan, its in that small strip of exposed fins on the side.

The temp sensor is weird looking. Take a hollow brass tube, about 3/4" long, and the diameter of a drinking straw. Flatten one end of it, stick wires in the other end, and put shrink tubing over the whole thing. It only sticks in the radiator about 1/2" or so.

MacADaYear

Oh I get what your saying. But that dosent matter. The posts ive seen before had the probe like you and I have but there is still air moving over it. Not directly on it no, but the air from the engine bay moves around the sensor.

Just something I read on another board im not sure if it really works

one03sierra

iTrader: (1)

the probe that comes with the dc controller is wrapped in an insulation.it is only 3/4 of an inch long. it goes between the fins as does the vsc probe. but since it is wrapped in insualtion and it is short it doesnt protrude as dose the vsc probe. and it mounts in the fins right next to the outlet. it does get a tiny bit of air. but not as much.the air from the engine bay may get to it a little. its just real nice to see it keeping everything cool at around 25 to 40%.

MacADaYear

Ah yea thats way better. I wish the VSC was shorter so it didnt stick out but I dont have the problem with cycling since I did a custom thermostat mod

baskin

With regard to the placement of the probe, you’re correct marc, the probe monitors the temperature of the coolant downstream from the fan and the controller adjusts the speed of the fan for a constant temperature at the probe. The temperature offset is built into the controller.

With regard to the air cooling the probe, the probe is not the issue. If you’ve ever watched the water flow through a canal, you probably noticed a gradient in velocity, the flow in the middle is at the highest speed, and the flow at the edges is zero. The same thing happens in a radiator, this lowers the thermal conductance from the coolant to the fin. The problem is that the fins have a higher thermal conductance along their length than conductance to the coolant, so the closer the probe is to the point where the fin is cooled, the less the measured temperature at the probe tracks the coolant temperature. This is more of a theoretical than practical problem since the controller can be offset to compensate for it.

The cycling problem is two fold and is easy to fix. One part of the problem is that the thermostat is nearly closed at the temperature that you’re trying to attain, so the water flow is very low (the closed thermostat is also indicated by the small change in temperature with the jumpers). The second part of the problem is that the fans tend to be very efficient at low speeds. The combination of the small amount of water being cooled and the high fan efficiency will cause the output temperature of the coolant to change a large amount for a small amount of change in fan speed, causing the system to oscillate. There are three solutions that will work:

1) The U/D jumper will add stability in order to compensate for the low coolant flow (be careful with this, the next two pins over are IGN and GND, you don’t want to jump across the two).

2) Raising the temperature of the controller will allow the thermostat to open more, resulting in an increase in the flow of coolant.

3) The best solution would be to lower the thermostat temperature, since this will also lower both the transmission temperature and fan efficiency.

marc_w

Awesome, thanks Brian!

(The 35A controller here is working great, BTW.)