Flap reset, how to? XJ40

I am getting no air to driver’s footwell and only meagre air to passenger side footwell. Good air output everywhere else. I hear about “flap reset” but can someone explain how to do that? Thanks gang.

Hi Dave …

“Flap reset” … that’s a new one for me.

There is a ton of information on the conditioned air distribution system in the archives but here’s a quick “Cliff Notes” on how it works …

There are two fan assemblies that pump high pressure air into the evaporator/heater matrix assembly (actually just a big box) from both the left and right side.

This high pressure air first passes through the evaporator (basically just a radiator which cools the air) and then through the heater matrix (just a smaller radiator that warms the air) the path of this air is dependent upon the position of the two blend flaps (two long roller pin looking things).

Now you may ask why would you cool the air before you warm it ??? Jaguar decided that if you first dehumitize … is that even a word? … air by cooling it, it’s is more comfortable when you heat it (Jaguar designers worked in strange ways :grinning:) The air is then pushed through the openings that go to the facia vents and footwells.

The two blend flaps (the pie maker type roller-pins) are positioned by the climate control ECU which receives inputs from the control panel and six different sensors.

I’m pretty familiar with this system and I’ve never heard of a “flap rest”.

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Does this refer to the “remove-flap-actuator-and-use-flat-bladed-screwdriver-in-slot-to-free-up-stuck-flap” routine?

Well, terminology aside, what would keep air from coming out of the driver’s side footwell? (and how can i fix it). That’s my question paired down ; )

maybe it does, I’m not sure…

I believe Mike is correct that a common problem is a stuck lower blend flap. This could prevent air from flowing out of both footwells and the vent at the end of the console in the back seat.

Here’s a side view of the climate control housing. The small pipes (only one shown) sticking down on the right are the two condensation drains. The two large pipes on the left (again only one shown) send air to the left and right footwells and rear console vent.

A single blend door (lower) controls the heated/cooled air distribution to the footwells, so you should be getting roughly the same amount of air on either side …however, if one of the blower motors isn’t working (common issue), that could account for the apparent lack of air flow.
Check the motors by pulling the blower fuse from each footwell fuse box in turn. If no change in flow when one of the fuses is removed, that means one of the blowers has quit. Worth checking first.

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Thank you guys, I really appreciate your help with diagnosing this problem. I’ll reply when I fix it!

Dave, there is a lot of information in the archives about this issue. You can find it by using the search tool: