AC > Condenser Fan Issues 2018 Nissan NV 2500. 5.6

[Bobby G]

Hello,

Does any one know what are the inputs that the main ECU is supposed to be monitoring to activate the condenser Fan. Is it pressure AC knob position? etc
In other words what are the inputs that are supposed to be driving the Condenser Fan? At what point does the Condenser fan kick on? As im reading the pressure switch output from the controller voltage goes up to 5V then the Compressor shuts down for safety. With out the fan working.
Here is a bit of a description.
The AC does work when the vehicle moves at certain speed. So as the Air is moving through the condense it keeps the High side pressure low enough to keep the AC ON and operational.
Once at a stop the High side pressure goes above 380 PSI or around there and then the Pressure switch safety cuts OFF the compressor.
The AC System is charged correctly and it does not have a leak. The amount of refrigerant is what the manufactures sticker on the hood is shown.
The door test does turn ON the Condenser Fan every time the test is activated. So the Fan it is operational. Also when jumping the wire from the Relay board does come on.
IPDM is also good, now bad relay nor IPDM issue.
Does any one have any similar issues or know about it?

What drives the condenser fan? Is it controlled through the IPDM and ECU via a CAN network? How do you see the ECM command through a CAN Network?
Thank you 

[crusty]

A dealer Consult service tool will show all the details.  It can also do an active test and force it to run.

The trigger for the electric fan is based on vehicle speed, engine temp, A/C pressure.

 

Now being you have a 2018 with the 5.6 you have a second electrically controlled fan.  That is the engine driven fan.  As I recall, that one doesn't really have any decent scan tool options.  The fan clutch can fail and the fan won't move any meaningful airflow. 

 

The initial description of what you are looking for sounds like you are searching for info on the electric fan.  What it sounds like is the fan clutch isn't working.  So not sure which fan issue you have, or if both?

[Bobby G]

Hey Crusty.

It looks like you are correct. My auxiliary fan runs when the test is performed. ( Door Test also)

As it appears the main fan clutch was not working. We replace the fan clutch on the main fan, the engine fan. The Clutch was not operating the fan at a higher speed. It was just running with the engine speed.

The issue is that the dealer that a was dealing with they diagnosed the whole AC issues as a leak. I'm in the refrigeration service industry and i know that i did not have a leak on the AC System. One was because when i would drive the AC would work fine. When i would stop that's when it would kick OFF.

Even though i had told them that appears to be some king of an issue on the fans. Due to the condenser not cooling down. ( Fan Issues).

At the time i was not sure when the primary Fan (Engine Fan & Clutch) or the auxiliary fan were supposed to come on.

The main fan and the clutch seemed to be a very interesting setup and design. Also there is not much talk about them. Special on this vehicle. as far as i can tell.

And again the auxiliary fan seems to come on as needed from the main ecu im assuming.

 

After replacing the main Fan Clutch seems that all my issues have been resolved.

 It is very interesting that there is no fault codes for the clutch on the main Fan.

A local mechanic some how had another vehicle in the shop same one 5.6 engine. As we were trying to diagnose my issue with his tool, he noticed that the other Vans main fan was moving much more air through it and running much faster. 

That promoted us to focus on the Fan clutch. Which was the correct issue. Even though originally  we were focusing on the small fan the auxiliary. But we could not find anything wrong with it.

We had looked at every HVAC diagram at the vehicle.

It does not seem to have much information on the clutch fan. It seems to be a hidden issues.

 

I want to thank you for the reply, you have the correct answers on this topic.

[crusty]

The electromechanical fan clutch has been around for close to 20 years.  The first one I remember was on a Cummins Ram truck.  Thought it was pretty trick back then. 

 

From what I can tell there are no codes because none of the electrical circuits are broken.  The clutch just doesn't hook up when told to do so.  Happens to thermal fan clutches as well.  This just has electrical control instead of a thermal spring.  Kinda strange to call it a clutch since there is no friction material inside.  Just the flow of silicone fluid that controls the coupling.  Something gave up on the control.  Not common, but not unheard of either.