Loud noise under dash

[Mikerson]

Hi folks, I wonder if you can help me identify a problem on 2001 E-250 5.4L.

We took the van on out for one last adventure on Sunday before the snow starts to hit. While driving about 35 on a paved flat stretch, there was a loudish thump from the passenger dash/footwell area. It sounded like somebody dropped a full water bottle onto the rigid plastic of the footwell area. Temps were in the 20s and we had only been on the road for 15 minutes so the van was on “mix” defrost and floor at full fan and max heat. Immediately after the thump, there was a whine sounded like it was coming from the lower dash in front of the passenger seat where the glove box would be on a car. Sounded like a small motor spinning freely, or maybe when you turn off a shop vac that is on its last legs. I was like “What the #&$@ is that!?” and thought it might be related to the HVAV system. So I turned the selector knob from mix to off, and that stopped the sound. After that I tried to recreate the problem by turning back to mix and defrost, but the sound did not return. We continued for another 30 minutes to our destination, parked/hiked, and then returned home without having any more noises or observable symptoms.

Has anyone else experienced this and have a fix? I am generally aware of the vacuum reservoir failure/fix, but thought my year was not among those affected. Could this be some kind of ac compressor issue as well?
Thanks in advance.

[N147JK]

Blower fan lose a blade? I had the plastic blower fan in my car break and of course it made all kinds of noises.

[carringb]

Turn the hvac on when you can, and let us know if does the same noise on Vent or Feet.

Those setting don’t engage the AC compressor, and if it still makes noise it’s the blower.

I had a similar incident, and it turn out my AC compressor suddenly self-destructed.

[Mikerson]

Ok, confirmed again this morning before work. No noises on any HVAC setting either with the van running or engine off. Looked under the hood finally, no oil or anything thrown around that I could see.

[maptester]

Originally Posted by Mikerson

Ok, confirmed again this morning before work. No noises on any HVAC setting either with the van running or engine off. Looked under the hood finally, no oil or anything thrown around that I could see.

I guess we should assume that the blower/fan is working correctly in all settings and from Lo to High speed fan settings.

[Mikerson]

Originally Posted by maptester

I guess we should assume that the blower/fan is working correctly in all settings and from Lo to High speed fan settings.

Correct!

The message you have entered is too short. Please lengthen your message to at least 10 characters.

[kbeefy]

Sounds like a HVAC Actuator or linkage issue.
I know when the recirc door in my F350 changes position it makes a pretty loud thump.


I would run through all the modes (def-vent-floor) and temp settings to confirm everything is working. If you find it is unable to fully engage or disengage one of the zones start digging in to see if something is stuck or broken.

[Mikerson]

Managed to recreate the sound today. Not isolated to when the AC compressor is running. The sound is higher pitched than it was at first. Sounds like a fan blade stripped on its drive shaft or something. Thoughts?

https://youtube.com/shorts/dLvkVtvLOb8?feature=share

[kbeefy]

Thats the blower motor.
Try changing fan speeds while it's whining.


Drop the motor and spin it to see if it's the fan, but every one I've heard like that has been the motor.

[86Scotty]

Agreed. Blower motor. If you're real lucky it's just got a bunch of leaves and twigs and junk in it. If you're not lucky it's the motor bearings dying, not uncommon in any older vehicle. If you're really not lucky it's a mouse in pieces in there. Not kidding.

Wow, they're really cheap. I was curious:

https://www.rockauto.com/en/moreinfo...t=6916&jsn=937