Thumping noise near rear A/C, 2016 xlt

[Chance A Tucker]

Having a bizarre issue where I'll get random "thump...thump...thump" spaced about 1 second apart coming from the rear AC system area when we open doors or the rear hatch on our 2016 xlt. Typically it's 5 to 10 of these "thumps" but yesterday it did it for what seemed like 20-25 of them.

Out of warranty though I'll end up taking it to the dealer anyway. Just wondering if anyone else had heard of this?

 

[Trainmaster]

Is the thumping coming from the passenger side rear quarter? If it only happens when the rear fan is on, the thumping you hear is probably the blend door motor with a stripped gear. They fail that way. There are two of them back there. One controls the temperature of the rear air conditioner/heater, moving a blend door. The other directs the air to the floor vents if it's hot and to the ceiling vents if it's cold.

The motors units are little self contained plastic gear boxes, and the gears tend to strip. The thumping you hear is the motor turning and the gear tooth slipping.

They are both accessible by pulling out the "package tray" in the inside rear quarter panel trim. It's a little difficult reaching the three bolts that retain each one.

Replacements are available for about $50 form Ford, $25 for after market stuff and maybe $8 for ebay Chinese junk.

 

[iimagine]

Is the thumping coming from the passenger side rear quarter? If it only happens when the rear fan is on, the thumping you hear is probably the blend door motor with a stripped gear. They fail that way. There are two of them back there. One controls the temperature of the rear air conditioner/heater, moving a blend door. The other directs the air to the floor vents if it's hot and to the ceiling vents if it's cold.

The motors units are little self contained plastic gear boxes, and the gears tend to strip. The thumping you hear is the motor turning and the gear tooth slipping.

They are both accessible by pulling out the "package tray" in the inside rear quarter panel trim. It's a little difficult reaching the three bolts that retain each one.

Replacements are available for about $50 form Ford, $25 for after market stuff and maybe $8 for ebay Chinese junk.

Exactly.

 

[Chance A Tucker]

Would it do this with the ignition off, key not even in the switch?

 

[Trainmaster]

I'm not sure. It might as the contacts in the motor try to operate the motor until the gears are in the proper "parked" position, which doesn't happen because they are broken. I'm not sure if the thing's live with the ignition switch off, but it might be, and it may be on the deluxe climate control and not on the manual one. Those are two different controllers.

Put your ear to the plastic trim over the inside of the passenger rear wheel. If the noise is coming from in there, your problem is the blend motor.

If the noise is coming from the driver side rear, it's the sub-woofer, but that's another story.

The dealers here in New York charge $225 for a "climate control evaluation". They listen to the right quarter panel also.

 

[Chance A Tucker]

It's definitely passenger side. I have a video I'm trying to upload but I'm noobing the forum and can't figure out how to do it.