Fan motor operates erratically, fan motor has been replaced

[OMalley401]

I have a 2020 Rubicon Gladiator with a weird quirk that's driving me nuts. If I leave the blower controls on a manual setting when I turn the Jeep off, the fan will start back up at that setting when I crank the Jeep up. If I have it set to "Auto" when I turn it off, once I turn it back on, it will not go above 1 on the fan speed and I can't change it. With the engine still running, if I set the fan speed to 5 (still blowing at 1) and then turn the jeep off and open the door to turn it all the way off, then start it back up, the fan will come on at the higher fan speed. From that point, I can reengage the Auto setting and everything will work just fine. The only thing that I must do is to manually turn the fan speed back up high before I turn the jeep off again. I just replaced the fan motor thinking that the relays to adjust the fan are integrated into the motor, but that didn't change anything. I've had the TSB done that addressed the hot air problem. I've made sure that all the fuses are properly engaging the fuse block, also made sure that everything plugged into the CanBus is set correctly. Where else should I look now? I've got other electrical gremlins going on, but this one is pissing me off the most. Suggestions??

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[Chasm]

Sounds kind of like the fan resistor failing on my old truck. That was much older tech than this though.

 

[OMalley401]

That's what's so damn frustrating. Everyone I have talked to, says about the same thing.

 

[Hootbro]

I've got other electrical gremlins going on, but this one is pissing me off the most.

What other electrical problems? You may have a cracked can bus star block that is located behind the glove box that is known to crack the solder joints and give weird issues.



If this was just a stand alone issue, there is not much that controls the fan motor other than the HVAC controller. That leaves either bad software or the HVAC controller itself.

If you have a high scan tool like JScan and not just a simple OBDII reader, I would scan the vehicle and see what if any codes that may be posting but not reach the level of tripping the check engine MIL .

 

[OMalley401]

Let's see. Here are the current electrical issues that I am aware of;

1. Auto function within the HVAC system operates the heat, air, and routing, but does not control the velocity of air movement. If it was set at 5 manually and then switched to Auto, the air flow does not change.
2. If I have the air set on manual, but use the remote start to warm things up, the air resets to 1 again like I left it in Auto.
3. I have a Magnuson SC with a custom tune. So when it shifts at WOT, it shifts hard. Now when it shifts into the next gear at WOT, it acts like it's missing. I let off the throttle, it stops missing, floor it, it's fine.
4. If I let the Jeep sit for a couple weeks, it will operate erratically. What that means is that sometimes it will fire right up just fine, sometimes it won't fire up at all, sometimes it will crank, but will run a rough idle and won't get above 2K RPM then dies. If I let it sit completely off for 2 minutes, it will crank right up and run just fine.
5. Sometimes it will crank and run fine, but feels like at reduced power. If I pull over, turn off the ignition, and open the door, restart the Jeep, it will run just fine.
6. Occasionally if I am driving and hit a bumpy section of road, it will die. Pull over, turn everything off for 2 minutes, fires right up and acts fine.

I have chased grounds and made sure that there aren't any loose connections. I am at my wits end with this POS. What little I have searched, could this be related to the CAN BUS system?

 

[Hootbro]

The supercharger charger and tune thing is it’s own issue and may or may not be related.

Generally with the can bus block previously mentioned, the whole dash board will light up like a Christmas tree and have other random issues like the stability track errors and others showing on the cluster.

Really need someone with a scope that can monitor and look at can bus wave forms and knows what to look at to see if it is dropping out or sending errant data. Cheap thing relatively speaking if you cannot afford professional shop labor to diagnosis is to shotgun a new can bus block but that is still a stabbing guess without data. Really need a OBDII high level systems scan to see what codes are flagging but not posting that would help narrow things down.

There is also another connector in the LH wheel well that is a somewhat common issue of getting corrosion in and causing issues mainly related to engine stuff that is worth a look.

https://www.jeepgladiatorforum.com/forum/threads/tcm-connector-preventative-maintenance.88516/

 

[OMalley401]

The SC related issue at WOT is a new development, that's why I mentioned it. As for the plug under the passenger side, I will definitely look into that. I typically keep this jeep at the beach and with the salt air environment, that plug would be a prime candidate for corrosion. As for the Can Bus lighting the dash up, nothing so far. I'll reach out to a tech that has that type of tool to see if there's anything going on. Thanks for the tip.

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