[Bob Lincoln]

Probably is the blend door. You can fix the problem of it switching when going uphill by installing the improved (larger) vacuum check valve that plugs into the power brake booster. The noise itself, not sure that can be changed.

 

[B10alia]

I don't know if I would mess around with it too much, you have to take a lot of things out to get at the HVAC in these cars (from what I understand, most of the dashboard) and unless you're really aggravated by the noise or the HVAC isn't working right, it could be more work than it's worth.
As to why it does this changeover, in case you were interested, the blend doors (as you probably know) are operated by engine vacuum. The check valve is actually a combination check/vacuum reservoir. Under acceleration, the manifold vacuum drops off and can no longer provide enough force to seat the doors closed and the system goes to defrost as a default. The larger check valve assembly provides a larger reserve of vacuum specifically to correct this, the low vac is a problem Chrysler has had for a while, I've heard.

 

[neon98rt]

i put a bigger booster in my car and the door flap sound still happens. But it could be because only my floor and defrost work . i gave up trying to figure it out until spring when i will take the dash off.

 

[SGspirit]

Grateful thanks for pointing me in the right direction.

According to the Haynes manual, you can remove the blower motor without removing the dashboard, but taking the whole heater assembly out requires removing the dashboard. Ouch.

My next step will be to check the various heater settings and outlets to try and narrow down what's wrong. I think the owner's manual lists what air goes where for each of the settings.

This started when I recently had the alternator replaced. For about 20 minutes after I picked up the car, I couldn't get the heater/fan to work. Then it made a different noise, and started working normally except for this plink sound.

 

[B10alia]

What kind of different noise? It could be a loose connection that's causing that electrical problem, but I think that and the plink are unrelated. They're two completely separate systems. Unless there's something physically rattling around inside.

 

[george w]

I suppose that something small could have fallen down inside the housing through a defroster vent. This is one of those niggling little noises that you either totally ignore forever or that you'll tear the entire dash out one day when you've decided that you've had enough ! Unfortunately I fall into the latter category.

 

[russ93spirit]

I think the "plink" sound is the closing of the door against the ductwork. There is a foam insulator material that has most likely deteriorated. What you are hearing is metal on metal contact when the door closes. I wouldn't worry with it.

 

[SGspirit]

I think the "plink" sound is the closing of the door against the ductwork. There is a foam insulator material that has most likely deteriorated. What you are hearing is metal on metal contact when the door closes. I wouldn't worry with it.

That sounds logical. I'll still test all the vents on the different modes. I can see the plink noise happening when I move the control from "Defrost" to "Floor", but I'd think it shouldn't happen when the car points uphill.

The other noise was one time only, so it's not something rattling around. This other noise happened at the same time as the heater/fan started working again after a temporary outage that followed the alternator replacement.

The sound system certainly sounds nice with 4 good speakers. I'm impressed that the cassette deck still works as good as new. It's 22 years old, and no other cassette deck I ever owned lasted more than a fraction of that.

I'm wondering if I damaged the wiper system hunting for the faulty ground. The wipers park in the right position, but when used, as air pressure from higher speeds increases, the swipes go farther to the drivers side until the driver side wiper hits the A pillar, and the passenger side wiper goes to almost directly in front of the driver. It's like there's some slack in the mechanism now, or the swipe is too long.

 

[Bob Lincoln]

The travel of the wiper arms is fixed by the mechanical linkage that operates them. You can remove the wiper arms and induce an offset by putting them back on a different spline, but the sweep distance remains the same length (arc). The only way I could envision it changing dynamically is if the wiper linkage bushings are chewed up and allow the linkage to move different amounts depending on load.

 

[neon98rt]

the plink happens when vacuum is low. I have read a lot of threads on it. I do believe the post above about the foam gasket rotting and now it is metal on metal since sometimes old foam blows out at me. I tried a new vacuum booster and a different heater control. It is either a bad line or bad door actuator. Unless both of my heater controls were bad.... Do they go bad often?

 

[Bob Lincoln]

My truck does make a lound plink when changing climate selections. It also periodically blows light gray foam out the defrost vents, like a fine ash. I guess that's what's referred to. Someday I'll be in there to replace the heater core and can address it.

 

[B10alia]

That wiper thing could be due to rounding of the keyway on the motor shaft. I went to do bushings on my Spirit, because the wipers parked all over the place and moved too far on higher speeds like you're experiencing, and found them all tight and working properly. There's really no good fix for that, I tried something with solder and a washer but the solder is too soft and just gets all banged out of the way after a short time. I don't know how that happened, possibly from using the wipers too much on icy windshields or leaving them on when they were frozen, but that's what happened. The motor keyway on the linkage crank looks like an hourglass now instead of a rectangular slot, which translates into a lot of slop in the wipers. Either way, taking the linkage out to inspect the bushings and keyway might be a good idea. I would think it was the bushings, I think the issue I had is sort of an anomaly but it is possible.

 

[SGspirit]

Yes, I know the keyway you mention. It's where the motor shaft connects to the wiper linkages. Mine was fine when I took it apart. Looked like new. But as I tried to figure out what was going on with the wipers, I must have moved something, so the first time I tried the wipers after reassembly, they tried to go down from the park position. Like having them 180 degrees out of position. So the keyway may be damaged. I'm not keen to take a look at it because I hate pulling the wiper arms and removing the cowl cover. But I should in case I can prevent it from getting any worse.

 

[B10alia]

You put the crank on backwards. I know, I did it three times before I got it back on the right way... probably no major damage done to the keyway. I like to test (seeing as today might be my fifth time taking the wipers off) the system with the cowls off and no wiper arms. I set it to delay and watch the pivots turn and try to visualize how the wipers will move. It's a couple less things to do if I have it backwards.

As for the issue of the blades overshooting, if your bushings are fine and the keyway is fine, it could be the blades. Winter style blades tend to lift and push more than the open frame summer style ones because the closed winter design has higher wind resistance. This, combined with the inertia loads of the linkage at higher speeds, could be forcing even minimal slop accumulated over 22 years to become obvious.

 

[SGspirit]

It's time to update this topic, specifically for the heater door malfunction.

Since this topic was active, the symptoms have gradually gotten worse. I narrowed down the problem to the "panel" setting on the heater, where all or most of the air is blown through the 4 vents in the top front of the dashboard. All other vents and settings seem to work fine.

At first, when in the "panel" setting, no air would come from the 4 vents under hard throttle such as going uphill. Gradually this has gotten worse until air will only blow out through the 4 vents if the car is level or pointed downhill, AND at idle. Since this car never had a/c, this has been quite a problem during our recent hot weather. I assume this means that only at the highest vacuum is there enough vacuum to keep the associated heater door in place.

Unless this update points the finger elsewhere, would these symptoms confirm the earlier advice that the vacuum booster needs to be replaced? Note that no vacuum hoses have ever been replaced on this car, now 22 years old and very close to 200,000km.

And if it's the vacuum booster, can it be replaced without removing the dashboard? I assume that it will mean at least removing the glove box, the lower right silencer, and also the console so the silencer can be removed.

 

[neon98rt]

the booster is under the hood. There are a few treads on this. with part numbers. You blend acuator is bad. I had the same exact problem. I have the blend door "motor" vacuum pump on ebay brand new.

Defrost only and no matter what button you hit nothing changed, except floor. Does it go to floor. and the plink you hear is the door closing. It use to have some foam on it and now all of the foam is gone. Metal on metal when it closes.

 

[SGspirit]

the booster is under the hood. There are a few treads on this. with part numbers. You blend acuator is bad. I had the same exact problem. I have the blend door "motor" vacuum pump on ebay brand new.

Defrost only and no matter what button you hit nothing changed, except floor. Does it go to floor. and the plink you hear is the door closing. It use to have some foam on it and now all of the foam is gone. Metal on metal when it closes.

The system seems to work normally except for the 4 dash vents ("Panel" setting), which only blow air if the car is idling and is level or pointed downhill. I also noticed the air flow from the panel vents does not increase at higher fan settings.

I checked the parts list/chart for the Spirit, and it doesn't have a "blend actuator". Among the seals, etc, it lists:
- heater blend door;
- heater mode door;
- door actuator;
- defroster door,
- blower motor.

Sounds like you're referring to the door actuator, the picture of which shows a vacuum device and not a door. I guess it would be easiest to start by replacing the booster in the engine compartment. Getting at the heater even without removing the dash is quite a bit of work. If this repair requires removing the dash, I 'ain't gonna do it.

 

[neon98rt]

it is either the booster or a vacuum leak.
I had the same problem with the heater control valve. At gas the vacuum would stop and it opened the heat on top of my ac. at idle it sayed closed or going down a hill and the ac worked great. Mine was just a loose hose that i had to make fit on the new control valve for the heater but it was too big. I cut it and made it fit better.

a vacuum guage is needed in your situation. It should be 25 psi . That is what mine was. Im sure yours will be zero.

 

[SGspirit]

Mounted next to the brake booster under the hood, there's the vacuum booster(?). From it, there's a vacuum hose that goes through the firewall into the interior under the dashboard. There's also a fitting attached to the brake booster that has a larger vacuum hose (5/8"?) and another thin black vacuum hose that goes through the firewall.

This latter thin black vacuum hose is almost completely severed, as though something was chewing on it. I say "chewing" because I can't see how else it could have gotten damaged.

Does this sound like it is the cause of my problem with the heater blend door? Is there a repair kit for the hose, or will I have to replace it? I haven't yet traced it in the interior.

Where, with respect to these parts, is the vacuum check valve?

From searching this problem, I see youneon98rt have recently been problem solving this sort of problem. Thanks everyone for the help.