I'm not sure if I am just stupid, but....
My question is,regarding the fresh air vent system. Should the flap inside the car be closed when the scoop out front is open? This is the way it is working on my ZB, but, to me, that seems backwards. When the outside scoop is closed, shouldn't the inside one be closed as well.
Any help, except agreeing with my stupidity would be appreciated

Steve

Hi Steve,

It's not you.
I've recently been attempting to figure out the convoluted heater/venting controls myself. See the reprint of the manual I've attached. What you describe happening on your car is correct. Fresh air (outside)drawn in when the cowl vent is open, and recirculating air (interior) with the cowl vent closed. The figure "C" is the setting where the backside of your dash gets a nice blast of outside air. Still confused? I think we're supposed to be. :-)

Ray

Ray,What happens is that when I open the outside scoop vent, the flap inside closes at the same time. That would mean that the fresh air is NOT coming in. Right?

Steve,

Your linkage may well not be 100% adjusted perfectly, but when the flap inside is closed and the cowl vent is open, the outside air goes through the blower and thus into the heater box. (hopefully) A picture is worth a thousand words so see the diagram attached.
Whether the air comes out hot, warm or cold, at that juncture is dependent on the heater (water) valve position. The valve must be closed to have any chance of coolish air, assuming your heater is connected to the cooling system. Air leaks anywhere between the cowl vent area and the heater box (of which there are plenty possible), plus radiant heating through the firewall sheetmetal, blower housing and duct may also reduce what little fresh air is possible.

They don't build them like they used to,
Ray

Ray, Many thanks. That whole "S" section is missing from my manual. would you mind e-mailing the pages in that section to me, please. Maybe then I can clear this up. However, I still don.t understand how the fresh air vent and the control flap can be closed at the same time. Maybe there's more info in those pages.

Cheers, Steve

Steve,
There are only two more paragraphs in the heater section. One deals with a production change where they changed the angle of the levers for better cable routing and the other is an instruction for optimal defrost setting!

Best of luck,
Ray

Steve, With MG's I don't think there are any stupid questions. I have a ZA and my vent does the same thing as you describe... It makes since to me that the inside flap would be open when the outside vent is in the open position...It is on my list to check out later, But may as well do it now since it is an opeen topic. I was going to look at it and see if someone had reversed the linkage somehow, but maybe these pics will clear up my questions. Thanks guys

Thanks Ray
Glenn, let me know, please, what you figure out.
Thanks, Steve

Steve,

The control for the vent box is as follows:

With the lever pulled fully rearward the external flap is closed and the internal flap (behind the radio) is fully forward. Air then flows from the inside of the car, through the airbox and fan into the heater and then out into the car again. Re-circulation in modern cars.

Next position is on the small ball detent about 2/3 of the way forward. The outside vent is half open and the inside flap is flush with the air box (closed). Air flows from outside, through the fan and directly to the heater unit.

Finally, fully forward the outside vent is fully open and the inside flap is fully rearward. Air now flows directly through the airbox and into the car, good to cool the radio.

The setup procedure is to first set the fully closed (rearward)position),the outer flap can be checked for a decent flush fit and adjusted by moving the brackets on the underside of the flap.

If you can get that correct then move to the mid detent position and adjust the inner flap to sit just flush with the air box, it doesn't really matter if the seal is just inside or just outside of the aperture. Adjustment is on the link to the inner flap.

That's about it, the fully open position is not really important.

I hope this helps a bit.

Paddy

What's a radio?

I use the radio to power the GPS nav system and the hands free phone.

Paddy, Thanks for all that explanation.In your first sentence you say that the internal flap is to be fully forward. Do you mean closed up against the box? This flap is on the outside of the box behind the radio? If so, then mine is backwards. The only time the inside flap is closed, is when the outside one is open. Doesn't seem right to me. Your description sounds the way it should work.
Is the bracket adjustment under the outside flap?
Thanks, Steve

Hi Steve,

Sorry, I made an error with the instructions so I have re-written them below with some extra information.

All directions are in relation to the car. Note: the control lever should be almost touching the underside of the dash when closed and as far forward as you can reach when fully open (about 80 degrees of travel).

The control for the vent box is as follows:

With the lever pulled fully rearward the external flap is closed and the internal flap (behind the radio) is fully rearward. Air then flows from the inside of the car, through the airbox and fan into the heater and then out into the car again. Re-circulation in modern cars.

Next position is on the small ball detent about 2/3 of the way forward. The outside vent is half open and the inside flap is flush with the air box (closed). Air flows from outside, through the fan and directly to the heater unit.

Finally, fully forward the outside vent is fully open and the inside flap is fully forward. Air now flows directly through the airbox and into the car, good to cool the radio.

The setup procedure is to first set the fully closed (lever in the rearward position),the outer flap can be checked for a decent flush fit and adjusted by moving the brackets on the underside of the flap. These can only be adjusted with the lever fully forward, so this is a trial and error system. I wouldn't try and get too tight a seal as it will strain the fairly weak mechanism.

You will need to remove the fly screen to get access to the two nuts under the flap. Loosen the nuts and slide the brackets forward to make the flap seal tighter, or rearward to make it looser. Try and keep them even to ensure the flap doesn't twist on the hinges.

If you can get that correct then move to the mid detent position and adjust the inner flap to sit just flush with the air box. The internal flap passes through the aperture in the airbox it is only sealing the hole when the lever is in the detent position.

It doesn't really matter if the seal is just inside or just outside of the aperture. Adjustment is on the link to the inner flap just above the lever mechanism. If you look closely there is a split pin and a small clevis on a stud. It is very fiddly to adjust as it is hidden behind the wiper flexi drive. Adjustment is on a slot in the bracket, loosen the nut and move the inner flap into position.

This only leaves the fully forward lever position. as you move the lever forward the inner flap will pass through the airbox and open into the inside of the airbox and the outer flap will rise to it's maximum height (about 45-55 degrees).


Hope this helps

Paddy



Edited 1 time(s). Last edit at 02/11/2011 03:19PM by paddyreardon.

Paddy, Thanks so much for the detailed explanation. Really appreciate it.
I'll try to go through those adjustments over the weekend.
Does your outside flap seal really well. I ask because I seem to get a lot of water inside the car'
which appears to be coming from the air box area and The drain hole is not plugged.
After driving in the rain, my floors are really soaked.

Cheers, Steve

Hi Steve,

Neither the inner or outer flaps seal particularly well, certainly not watertight.

You are aware there are two drain holes in the airbox. One could be disconnected from it's drain pipe. If it's not that then I suggest you may want to look at two areas, the first is the inside of the hole where the heater fan mounts on the bulkhead, It gets a lot of moisture and doesn't have a drain so it rots through into the cabin above the heater. The second is the wiper ferrules and window sprayer fittings, both have leaked at one time or another on my ZA.

I never get any water inside the car no matter what the driving conditions. However, last time I went to the car wash, I felt extravagant and went for the "Platinum" wash, I usually use the "Gold", unfortunately I didn't count on the high pressure horizontal jet coming through the quarterlight seals. Got soaked 4 times.

I guess you could try the local car wash and try to see where it is leaking from. It won't do the car any harm.

Paddy

Paddy,I see the 2 drain holes. The left one has a drain pipe, the right not. Perhaps this is the problem.
Thanks, again.
Steve

Steve,
Since you're doing a thorough job, be sure to look at where the wiper wheel box shafts go through the airbox. The "airbox" is going to get water in it. Unlike most cars, it's not enough to just seal the wiper bezels to the exterior cowl. From the perspective of the wiper arms, the shafts run down through the airbox, then into the interior under the dash. The original sealing is by some thin rubber, like bicycle inner tube.

I used some foam water pipe insulation, like you find at OSH, to seal between the box and shafts. The insulation is inexpensive and comes split, with adhesive to make full round. I think what I used was about 1/2 inch id. If you take the nuts and chrome bezels off you can let the whole assembly down into the car slightly. Cut a length of the insulation long enough that a wee bit will stuff up into the holes when the wiper assembly is fitted back up tight on the cowl.

One more thing, if you look into the bottom of the airbox, there are four 1/4 inch captured nuts. These are used to hold the pair of dash brackets for the radio, vent lever, etc. These originally were gouped up by the factory so not to leak through. This may well have dried out and disappeared.

Forget the car wash, just have a helper run a garden hose (at modest flow) over what ever area you're checking for water leaks. Not as much drama!

Also, I don't think any adjustment you're undertaking will require taking the flyscreen off. Not easy if the screws are rusted. (they are)
Ray

Ray, I'm not actually doing a thorough job. This car was restored(not by me)
about 15 years ago. I've had it for 3 years and only recently decided to try to
find the source of this almost instant fogging up on any wet day. Founf the floors
absolutely soaked, therefore the fogging.
Now I need to find the obviously major leaks. I did find that one of the 2 drains does
not have a pipe on it, but, I'm not convinced that it's the culprit. For sure I'll
attach one and see if things change.
Thanks for all your good ideas. Looks as though you can do all that stuff(or have you already)
with the front end open like that
Steve