Heater vacuum actuators

[Tanz]

The two vacuum actuators that are on the side of the heater and operate the heater flaps are not working. Neither one will hold a vacuum. One will work if vacuum is applied and I push it to give it some help but it still won't hold a vacuum.

My question is where can I get replacements from? looked at SJ Sports cars but can't see them on there.

[Dave Eds]

GeofSmith's loft?

[Rambo]

I think Geoff is currently the Guinness world record holder for the amount of heater vacuum actuators he has in his loft

[Dave Eds]

I had more.......

[dapinky]

Are they part of the matrix/heater unit???

If so, I *may* have one or two in my loft........


..... assuming that you mean items #2 & #3 on page 18.01A of the parts book, I'll have a look when I'm next in the loft (which may or may not be this week, depending on when Angie wants the Chrimbo Decs bringing down).

[Fredjohn]

Dave's offers a good one, but try a bit of silicon spray or WD40 on them first. And on the flap hinges too.

[Dave Eds]

IIRC Dave those bits were present on some but not all of the units that accompanied me to Castle Combe in my old Insignia ........

[dapinky]

In that case spud, I may or may not have any on the half-of-the-bootful that I ended up with.

[Tanz]

Are they part of the matrix/heater unit???

If so, I *may* have one or two in my loft........


..... assuming that you mean items #2 & #3 on page 18.01A of the parts book, I'll have a look when I'm next in the loft (which may or may not be this week, depending on when Angie wants the Chrimbo Decs bringing down).

Yes - it's items #2 & #3. Between now and the weekend I will remove them from the heater unit. If I apply a vacuum using one of those guns you use to bleed brakes they don't move or hold vacuum. At the last 2 MOT's I was told there was a vacuum leak somewhere and the idle mixture was very weak. Most of the dash is out so i'm nearly at the point where I can get to them. I will try a bit of WD40 as one of them moves if manually pushed to get it started. The 3rd one that operates the recirculating flap on the left hand end of the dash works perfectly.
But if anyone has good ones to sell (#2 & #3) I would be very interested.

[Tanz]

OK, so after removing the whole dash board, (easy if you say it quick) I removed the two vacuum actuators - one a single action and one a double action.
Applying a vacuum to them using the brake bleeding gun resulted in no movement at all in either of them and also neither of them would hold a vacuum. However, I noticed if I squeezed the two halves of the body together on the single action one, it worked fine. So the leak was between the two halves of the body.
I carefully separated the to halves of the body, applied some gasket sealer and pushed it back together. Now works fine and holds vacuum.




The double action one had the same problem. The body on this one is in three sections and much more difficult to pull apart. I damaged it trying to separate it but with the benefit of hindsight there was no need to take it apart. Just seal it on the outside by pushing sealer into the joints and it would be fine. I managed to get a second hand one that worked perfectly but sealed it on the outside anyway in case it failed in the future.

[RonR]

Hmmmm....

I wonder if this could be the cause of my heater never delivering cold air, even in summer?
The car has a new Volvo water valve and all the vacuum pipe connections were checked, but the vacuum was still a bit on the low side, even after doing the "Tap Washer" trick with the bleed valve.

Please stop me... I feel the urge to take the Dash out.....

[Tanz]

Hmmmm....

I wonder if this could be the cause of my heater never delivering cold air, even in summer?
The car has a new Volvo water valve and all the vacuum pipe connections were checked, but the vacuum was still a bit on the low side, even after doing the "Tap Washer" trick with the bleed valve.

Please stop me... I feel the urge to take the Dash out.....

A couple of things you can check before taking the dash out.
When you turn the hot and cold dial does the water valve move? When moved to the closed position the valve should close and stop delivering hot water. In any other position the valve should be open and hot water should pass through the heater matrix. Temperature is controlled by how much air passes through the matrix or around it. So the water valve is on or off. If there is no vacuum in the heater control pipes it wont close. It will be stuck on all the time.

Also the hot/ cold control is linked by a rod to a flap on the heater box which in turn operates a micro switch which directs vacuum to the heater valve. If the rod is badly adjusted (it can be adjusted by turning it) the flap won't close sufficiently to operate the micro switch. This was the case with mine. When I turned the hot/cold dial the heater valve didn't move. After removing the dash and applying vacuum with the brake bleed gun - if I pulled on the rod to it's full extent the valve moved.

If you locate the main feed pipe to the heater system in the engine bay and apply vacuum to it (brake bleed gun) - see if it holds vacuum. If it doesn't there is a leak somewhere. You can eliminate the reservoir located under the wing by clamping the pipe that comes out of the reservoir with a brake line clamp and applying vacuum.

[RonR]

Thanks for that explanation Phil, it gives me more things to look at before resorting to dismantling the dash.
Unfortunately my brake bleeding set is a "push" rather than a "pull" jobbie, so I think my next tool purchase will be a vacuum gun!

[roy666]

Hi Chaps..tagging on the end of this topic; is removing the dash the only practical way to sort out heater control and air problems? I have only hot air coming through because the heater temp knob is stuck solid, and the air only comes through the wind screen vents and no where else despite turning the selector knob to any of the other positions;... ok, a little air does come through the lower foot well vents and I do here something going clunk... but nothing on the other positions. I'm assuming it's all to do with stuck vacuum valves as described previous on the thread.... i already have stereo out, ash tray out and about to pull out the heater control panel. I can get to the hot/cold microswitch but can't really see any vac valves to check. Seems like it really is a dash out job? cheers Mike

[Fredjohn]

Before you start removing the dash, check that the vacuum pipes to and from the reservoir are connected.

You will however need to remove the passenger wheel arch liner to get at the reservoir. Once those connections are checked, then look at the other end of the pipe from the reservoir to the distribution box behind the dash.

It's worth looking at the for once excellent piping layout section PE in the workshop manual. P14c for the 4 position knob or P15 for the 6 position knob as appropriate.