960: 97 960 vent control issues

[MrBill]

Okay I just bought this car. It was cheap and is in pretty good condition.

The A/C works fine. HOWEVER:

The vent control doesn't work properly. I did some searching but my situation wasn't documented. It's not a vac leak from the motor I don't think.

Here's the issue. I have the rotary dial-style A/C control. I think later 760s through these 960s had a similar setup. The floor and defrost seem to always be blowing. If I select the front vents, all of them blow. If I select defrost, the front vents turn off and the defrost and floor still blow.

Any suggestions?

[badvlvo]

Check the blend door and actuator. It could have something like a pen or some other foreign object keeping it from working.

[15A]

BTDT with my 760 a few years back (its the same part - I replaced mine with a 98 V90's). Right behind the glove box and to the left is a gold "distribution block" - about 2" x4" with a colored assortment of vac lines (purple, pink, etc) coming in and out of it. Can't miss it. These are known issues over time and big $ to buy new. Find one in a yard and replace it. Very quick and easy swap.

If you can't find one, I probably still have a couple known good spares.

[MrBill]

Originally Posted by 15A

BTDT with my 760 a few years back (its the same part - I replaced mine with a 98 V90's). Right behind the glove box and to the left is a gold "distribution block" - about 2" x4" with a colored assortment of vac lines (purple, pink, etc) coming in and out of it. Can't miss it. These are known issues over time and big $ to buy new. Find one in a yard and replace it. Very quick and easy swap.

If you can't find one, I probably still have a couple known good spares.

Dumb question:
How far back does the same gold distribution block go?
I have an 86 760 that is being replaced. It has 315k on it and I was thinking about parting it. it has the 'automatic climate control' but it isn't the rotary knob thing. I know it has colorful vac lines inside. The climate control in the 86 works fine - same distribution block?

[stove]

88-98 ecc

[15A]

Originally Posted by stove

88-98 ecc

What he said.

But as with everything....the newer the better. If I still have mine, they were pulled from a 97 960 and a 98 V90 (68k and 77k).

[MrBill]

Okay so I dove under the dash today

First - I find this:

I assume this is the golden box.

Next - on the driver's side, I find these:

I assume these are the vacuum servos?

So I turn the vent control knob and I put my hand on the golden box - every time I turn the knob, I feel a movement in the box. That's a good thing I'd say.
So I looked under the hood and traced the vac lines. Every one of the rubber elbows were cracked/dryrotted/not capable of holding air.

I went to the parts store, got some vac line, and voila! working vents. I did find that when I accelerate the vents seem to fade away. It would seem the check valves aren't doing their job.

[FlyingTog]

Originally Posted by MrBill

I did find that when I accelerate the vents seem to fade away. It would seem the check valves aren't doing their job.

Mine does that. When people ask why, I tell them the car unlocks the A/C compressor clutch at WOT for moar powar.

[500dollar744ti]

it's probably one of the servos. every single 960 does it to an extent but the properly functioning cars will take lots of WOT before the vent flow starts to drop off.

the cars that have a real issue will lose flow to the vents under light load and full load and it will be somewhat intolerable.

i've added a vacuum reservoir to my s90 in addition to the one that's already there. i fault traced and couldn't find any leaks in the vacuum control block, lines or servos. the vents only loose some flow under long periods of heavy acceleration. i've seen every 960/s90/v90 do this to an extent even when they were pretty much new. adding the extra vacuum reservoir has stopped it from happening altogether.

edit:// i thought you were talking about the issue we discussed on the phone, didn't even read your post up there. if the air distribution doesn't respond to the selected position, it's usually the vacuum block itself.

[MrBill]

Yeah I'm going to make a vac reservoir out of some pipe or something.

[MrBill]

Okay so I was thinking harder.

IIRC - my 760turbo (86) has a vacuum pump. When I have the hvac system running and the motor isn't running, this pump will often turn on.
Maybe i could set up some sort of vacuum switch (engage if vac is under X) and use that pump?

[TrickMick]

Originally Posted by MrBill

Okay so I was thinking harder
IIRC - my 760turbo (86) has a vacuum pump. When I have the hvac system running and the motor isn't running, this pump will often turn on.
Maybe i could set up some sort of vacuum switch (engage if vac is under X) and use that pump?

let Frankie Goes To Hollywood guide you:
"Relax, don't do it ...when ya wanna get to it...relax....."

strip a spare set of "vacuum balls" out of a J/Y car and plumb it in-line.....
un-neccessarily complicated shiite tends to back fire on ya... a "spare
set of balls" never hurt anyone......

[MrBill]

But then I can't go cockswinging with my vac pump

[linuxman51]

Originally Posted by MrBill

But then I can't go cockswinging with my vac pump

hahahaha. it's been discussed before, using a vacuum pump to drive the hvac system vs the engine vacuum.