Rebuilding the ac/heater control switch

3175375

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I am going to have to chase out the switched vacuum hoses. On initial peek at the lines, I see the extension hose bundle, and shortly after that, I see one of the 3 tees.
I don’t see the bleed wire (really a hose).
Does anyone have any reference material on how and where the tees are routed/located?

I have a feeling that some things are missing…

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david hill

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The photo below shows where to look for the vac. supply hose or or fab one yourself as indicated below. The tee is located under the right bottom of the heater box. To be sure you have the right tee, follow the hoses. One should end at the recirculating air dampener.

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3175375

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The photo below shows where to look for the vac. supply hose or or fab one yourself as indicated below. The tee is located under the right bottom of the heater box. To be sure you have the right tee, follow the hoses. One should end at the recirculating air dampener.

View attachment 529629
I have these diagrams in the FSM.
I was hoping that someone had created a sketch for the vacuum hoses as they are color coded (red, yellow and green stripes on some of the hoses that I saw in poking around).

I guess I am going to have to make my own diagram.
 

3175375

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I have found a few pictures of the actuators, with commentary by @Trace 300 Hurst , @bigmoparjeff and others.

I am going to trace out my existing plumbing and create a ‘schematic’ of the control vacuum hoses.
I don’t have any information regarding the ‘bleed wire’ referenced in the FSM. Where it physically is, how it’s mechanized and if it has a restrictor on the end of it or not.

Interestingly, the 68 ac/heater box uses a 2 port actuator for the defrost/heat and the 69 (I bet 70 is the same) uses a single port actuator. This is why port 2 on the mode control switch is capped.
Finally, the reference diagrams for the 68 and 69 mode operations (showing switched vacuum to the actuators) is referenced opposite for ports 5-7 (see pictures)… the diagrams are port reference number only and not physically laid out the way they are depicted in the figures.

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3175375

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Been chasing out the vacuum hoses. Totally mis-plumbed.
Found the bleed wire - PO stuck a wire in it!

PO also:

Had the temp hoses way wrong, put a tee in a hose that didn’t need it.

Here’s what works (manually operated with a mity-vac):

Vacuum reservoir
Defrost/heat actuator
Time delay relay

Here’s what doesn’t:

A/C heat actuator (on driver’s side of the heater box)

Recirculate/Fresh Air actuator (one hose moves it, the other does nothing) - I might be able to get away with this as it may return to that position, but it would create a vacuum leak.

I ordered a A/C heat actuator from Hilltop Motors - they have an NOS that I snagged.

To do:
- mark and remove unnecessary tee in one line
- add a tee for the vacuum source to the temperature control vacuum regulator

Check vacuum lines to the recirculating/ fresh air actuator

Pull the defective actuators and determine if I can find a recirculating/fresh air actuator or rebuild the one I have.

Reconnect everything and tie up all hoses and wiring after verification of proper operation.

Lots of messed up things that I will correct….

I will post some pictures probably on Monday…
 

3175375

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Found this video which is very helpful!
(Thanks to @marty mopar for posting it).



I discovered that there actually is a wire that goes into the bleed wire reference.
Additionally, all of the actuators use a red and white striped vacuum hose - the red stripe goes on the rod side of the actuator and the white stripe goes on the pot side.

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I am going to attempt to remove the recirculate/fresh air actuator and/or duct assembly to get to the actuator.

I also need to check whether I have an early or late AC/heater box.

I also am looking for the recirculate/fresh air actuator…
 

Trace 300 Hurst

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In my case, the recirc/fresh actuator was sticky going to recirc position but easily opened for fresh. But I don't want fresh, I want recirc'd AC air only, so I pulled and plugged the fresh hose and moved the door to recirc permanently.

Two other considerations about my "fix":
The fresh door is an open highway to mice, so you have to remember to go to recirc when you store the car.
Our cars are generally pretty leaky around the window seals, etc. already, so it's not like your not getting new air in the cabin.

Mouse nest behind glove box when I got the car. :mad:
Mouse nest.JPG





I am going to attempt to remove the recirculate/fresh air actuator and/or duct assembly to get to the actuator.
 

marty mopar

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so what you are saying is the mice were smoking and left that cigarette .....damn those mice!!!

If I had to deal with all those hoses, tees, switches, etc. I'd have to sell the car....way too complex a mess. Glad you are trying to fix it!
 
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Trace 300 Hurst

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so what you are saying is the mice were smoking and left that cigarette .....damn those mice!!!

If I had to deal with all those hoses, tees, switches, etc. I'd have to sell the car....way too complex a mess. Glad you are trying to fix it!
And eating a grape lollipop. :)
 

3175375

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so what you are saying is the mice were smoking and left that cigarette .....damn those mice!!!

If I had to deal with all those hoses, tees, switches, etc. I'd have to sell the car....way too complex a mess. Glad you are trying to fix it!
Not too hard, once the operation is understood.
The slideshow that I discovered is priceless in helping.
 

3175375

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Actuator repair underway!

Took the heat/defrost actuator apart and discovered that the diaphragm is good.
Problem is that it slipped off of the disc that the rod is tied to. Secondly, the exterior seal around the rod has a crack.
Re-attached it to the rod.
To repair the exterior seal, I put a ziptie around it after applying black RTV, then buried it with more RTV.

We’ll see tomorrow after it cures.

I also pulled the recirculate/fresh air actuator and it is good.
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3175375

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Actuator repair underway!

Took the heat/defrost actuator apart and discovered that the diaphragm is good.
Problem is that it slipped off of the disc that the rod is tied to. Secondly, the exterior seal around the rod has a crack.
Re-attached it to the rod.
To repair the exterior seal, I put a ziptie around it after applying black RTV, then buried it with more RTV.

We’ll see tomorrow after it cures.

I also pulled the recirculate/fresh air actuator and it is good.
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This is where the diaphragm popped off of the metal disc that is tied to the actuator rod.
The picture shows it attached correctly.
I may run a bead of RTV around the base, to ensure that it stays put…

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sprice

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Good work!
Does it work?
The vacuum tits on my control switch are in good shape, so I didn’t have to do these steps.

Good work!
Does it work?
The vacuum tits on my control switch are in good shape, so I didn’t have to do these steps.
The rivet pin holds nicely. That part I am very pleased with. HOWEVER, I may have drilled to far into the plate under the pins. I cannot get any movement from the door actuators. I checked each hose connection with a vacumm pump and gauge and it was weak so I suspected the actuators themselves were not holding air. Removed and tested and they seem to be ok. I am thinking I have either and hose leak to the actuators or that I drilled to far. I will return with an update once I figure this out.
 

3175375

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The rivet pin holds nicely. That part I am very pleased with. HOWEVER, I may have drilled to far into the plate under the pins. I cannot get any movement from the door actuators. I checked each hose connection with a vacumm pump and gauge and it was weak so I suspected the actuators themselves were not holding air. Removed and tested and they seem to be ok. I am thinking I have either and hose leak to the actuators or that I drilled to far. I will return with an update once I figure this out.
Behind where the vacuum ‘tits’ are, is a piece of rubber, covered with a small steel cover and a slot in it.
One of the mica flat pieces has a tab on it that fits in that slot. The mode switches move the rubber piece to ‘switch’ where the vacuum goes.
When you drilled the holes for mounting the rivets, you may have drilled into the rubber piece, which would create a vacuum leak.
I pulled the rubber piece out and it’s tricky to get it out, but do-able, if you are careful.
 

3175375

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The rivet pin holds nicely. That part I am very pleased with. HOWEVER, I may have drilled to far into the plate under the pins. I cannot get any movement from the door actuators. I checked each hose connection with a vacumm pump and gauge and it was weak so I suspected the actuators themselves were not holding air. Removed and tested and they seem to be ok. I am thinking I have either and hose leak to the actuators or that I drilled to far. I will return with an update once I figure this out.
Here’s a couple of pictures that may show where you might have drilled into the rubber and possibly the metal cover behind the vacuum tits.
If you perforated the rubber piece (68 unit shown, black here - in the 69 switch that I repaired it’s red), then you’ll not get a seal ‘through’ the vacuum switch…
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3175375

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To ensure that the diaphragm stays behind the collar above it (I tested the actuator and the diaphragm popped around the collar), I dug a washer with a rubber grommet out of my loose parts pickle jar that fits perfectly, assembled it and applied some JB-Weld right above the washer.
This will provide a larger area to keep the diaphragm where it belongs.
This may reduce the stroke of the rod, but the reduction will be minimal.
I will report back regarding testing…

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sprice

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Here’s a couple of pictures that may show where you might have drilled into the rubber and possibly the metal cover behind the vacuum tits.
If you perforated the rubber piece (68 unit shown, black here - in the 69 switch that I repaired it’s red), then you’ll not get a seal ‘through’ the vacuum switch…
View attachment 530760 View attachment 530761 View attachment 530762
I believe I did drill too far. Lesson learned. I have an NOS a/c heater control and removed a heater control off a parts car I have and bench tested with the actuators on the floor of the car. I checked all the lines with a vacuum pump and all are holding air and moving and holding correctly. with both units the actuators extend on DEF mode and retract on OFF. The shorter shaft actuator retracts on HEAT mode however no, or little air through the floor vents. I rebuilt the air box some time ago and all was cleaned and lubed (if possible, can't remember). The flaps, I am sure could only be installed one way so don't think that's the issue. I only have vacuum lines for two actuators so I think all that is correct. Is there something I am missing or should be trying? The red stripe vacuum lines are on the shaft side from what I read in above post from Detmatt however a different system. Its a non/ac 68' 300.
 
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