Vent noises from hot 2 cold

My 89 is making noises when i turn the tepm dial from highest to lowest setting sounds like the flap is bagging how can i fix this?

The fresh air / recirculate flaps are connected so that when one opens, the other closes, and vice versa. When you change temp setting from hot to full cold, the fresh air flap will close, and the recirculate flap will open. You might be hearing the fresh air flap hanging up, and then releasing, as it tries to move .
This happened on my "88 after I pulled the LHS blower motor to repair it.
Without starting the engine, reach down under the blower motor housing, and manually move the recirc. flap. It should move (with the upper flap) smoothly, and silently. If you can feel or hear any kind of scraping, you can loosen all the mounts on the blower motor housing and move the complete ass’y around a little until it is centered. A fiddly operation that will test your back, but it cured the odd flap noises in MY car. This is just one possibility, of course. There may be other problems.

Thanks ,this just started last Saturday got a little cool turned the head on got hot went to turn it to cold and it started to bang before that it worked fine . In a side note temp gauge is still not working ,i changed the sender ,it was working from time to time now not at all more fun stuff to work on.

The recirc flap that DavetheLimey is talking about rarely moves; only when the system is calling for maximum cooling or maximum heat. 95% of the time it remains in outdoor air mode. It might just have been the first time it’s tried to move in a long while.

The doors are supposed to be covered in a foam seal, so when the flaps shut it’s pretty quiet. With age the foam rots away and the flaps shut with a clunk. Besides that, DavetheLimey is correct, it is a bit tricky to get the fan installed just right so those flaps move smoothly without scraping something.

Its like a tap tap tap it keeps going until i put it back to the highest heat then it stops

May be something stuck in the blower wheel. When running slow, it hits something. When running faster, it flexes or something and doesn’t hit any more.

AFAIK, also when you turn the ignition (ACC) or the climate control off.

It seems as though you may have a blower wheel problem, so here is a way to find out.
Turn the ignition on, without starting the engine. Turn the RHS climate control knob to low. The blower motors should start up. Do you hear any noise? Turn the control knob to medium. If there is a noise, does it increase with the speed of the blower?
If you determine that it is indeed a noisy blower , this could be why-
One of the blowers on my car became really noisy, about a year after I got the car. , Clattered like it was coming apart. It was the LHS blower ass’y. I removed the blower box, and discovered that the squirrel cage had become loose on the end of the motor shaft, and was rubbing the housing. From memory, the motor shaft has a “D” shape end, and the squirrel cage is just pressed on. Rather than look for a complete new ass’y, I thought perhaps I could fix what I had.
I drilled and tapped the end of the shaft to 6/32, IIRC, and with a washer, a machine screw, and Loctite was able to secure the squirrel cage back in place. That was six years ago, and no more clattering.
If your noise is one of the blower motors, just find out which one it is by pulling fuse #10 in the main fuse box, or fuse #5 in the auxiliary box, and go from there.

Nope its in the flaps blower is off . I move the temp control from hot to cold and it starts a rhythmic popping like the vent is slipping on a gear . How hard is it to get to the flaps its an 89 convertible it sounds like its coming from the center of the dash

What year is this car? Delanair MkII or MkIII?

A 1989 car- so surely a Delanair#3. Upper/lower blend flaps. I hope Kirbert can help you as I haven’t had to get that deep into my own A/C unit. Darn.

Both the MkII and MkIII have upper and lower blend flaps, but on the MkII they are operated by links from a central servo mechanism. On the MkIII they are operated by individual servo motors that are notorious for stripping gears – which sounds like what has happened here. Unfortunately, the upper servo motor is also notorious for being a b$%^ to get in and out, and they’re also stupid expensive to replace.

I have a notion to replace one of these crapped-out servos with a servo from some other type car and mounted in a convenient location, actuating the flaps via a link up into where the original servo was mounted. But I didn’t get any interest in discussing it the first time I brought it up.

How do i get at it is it behind the motor or in through the dash

Each blower is off-set from the main unit- one on each side. There is nothing behind each one This is the RHS .

You have to go in from the front, AFAIK.