electric fan problems

phum · **Posted:** Sat Dec 23, 2017 8:05 pm

the electric fan doesn't operate. If I pull relays ( as instructed here on lost) it operates on both speeds. What activates this fan and where do I go from here to fix it
P.

flash7210 · **Posted:** Sat Dec 23, 2017 9:28 pm

fan is activated by the coolant temperature being above 205F or any time the air conditioning is on

seems to me that your electric fan is working

WWDiesel · **Posted:** Sat Dec 23, 2017 9:53 pm

As Flash stated, seems the fan is doing what it is supposed to do functionally!
What do you perceive as the problem with it?
More information would be most helpful in diagnosing your problem and offering good advice.... :roll:

phum · **Posted:** Sat Dec 23, 2017 10:28 pm

Fan doesnt operate at all with ac. or engine temp. rise when going slow towing causeing engine temp gauge to go off the scale and trans oil temp to overheat. Turning off ac doesnt help

flash7210 · **Posted:** Sat Dec 23, 2017 10:36 pm

It would be helpful to know exactly what temperature the coolant is getting up to.
Same with the transmission temperature.

Unless you are operating under extreme conditions, the engine driven fan alone should be enough to keep things cool.

phum · **Posted:** Sat Dec 23, 2017 10:47 pm

Dont know exact temps but ennine temp was off the scale and trans oil temp light came on and trans was reluctant to shift..I think engine fan is adequate at highway speed but not going slow.

phum · **Posted:** Sat Dec 23, 2017 10:58 pm

I am confident it is an electrical problem, pull the relay and the fan works and everything is normal but I would prefer to fix it properly

phum · **Posted:** Sun Dec 24, 2017 1:17 am

I think I read somewhere that one speed setting was triggered and controlled by the ecu and the other by the ac. Is this correct?
What in the ac system triggures this?

WWDiesel · **Posted:** Sun Dec 24, 2017 1:14 pm

phum wrote:

I think I read somewhere that one speed setting was triggered and controlled by the ecu and the other by the ac. Is this correct?
What in the ac system triggures this?

From the FSM,
The A/C high pressure switch controls both A/C compressor clutch engagement/disengagement, and electric cooling fan operation when equipped with the 2.8L diesel engine. The A/C high pressure switch is mounted on a fitting located on the A/C discharge line near the A/C compressor. The A/C high pressure switch turns off the A/C compressor if the refrigerant system pressure exceeds 3100 - 3375 kPa (450 - 490 psi).

The A/C high pressure switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the A/C discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the A/C discharge line pressure drops to 1600 kPa (235 psi).

The A/C high pressure switch contacts open when the A/C discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The A/C high pressure switch contacts close when the A/C discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi). The A/C high pressure switch is factory-calibrated and cannot be adjusted or repaired. If the A/C high pressure switch is faulty or damaged, it must be replaced.

The A/C low pressure switch monitors the pressure of the refrigerant leaving the accumulator to the A/C compressor. When equipped with a diesel engine, the A/C low pressure switch is electrically connected in series with the A/C high pressure switch, between ground and the engine control module (ECM).

Both fan speeds are controlled by the ECM from various inputs from the A/C pressure switches, engine coolant temperature sensor, and the transmission temperature transducer via the TCM.

:SOMBRERO:

mass-hole · **Posted:** Sun Dec 24, 2017 1:58 pm

The low and high speeds are triggered by the ecu on coolant temp. Low will trigger and then high a few degrees above that. It also stays on for an extended period even after coolant temps go down.

Your engine driven fan should provide the flow you need at low speeds if the clutch is working properly.

Sent from my iPhone using Tapatalk

phum · **Posted:** Sun Dec 24, 2017 5:39 pm

Thanks for such detailed help. At this stage I will assume that the ecm is not sending the signals. I will contact Marco, Yeti in the new year to see if he can check the tune he did for me and make sure that the fan operation is still functioning.
As an aside the cannister behind the battery freezes within a few seconds of starting the ac. I have been told this is normal but I have never seen it in another vehicle.

Have a happy festive season and a prosperous new year.
P.

electric fan problems

Who is online