Vacuum problems with HVAC and lighting.

[67_Eldo]

I've heard about Cadillac Tim's book and I think I need to get it. How can I do so?

In the meantime, I intend to pull the instrument cluster and clean up/renew the speedometer. To do so, I need to pull the left "climate control" boot from the dashboard vent. The manual does not offer much detail here. I think I can remove the hose from the center vent and one little screw from the top of the boot-to-left-dash-vent intersection, and then pull the whole (long) plastic duct out through the top of the dash? I don't see anything else holding the duct in there.

Once I get the duct and the instrument cluster out, the real fun begins: sorting through the vacuum hoses. Right now, the climate-control switch only seems to control fan speed. No matter what the setting, the air always comes out the defroster vents. Also, when the switch is in the Vent position, it feels as though the heater is on. So I need to make sure the heater valve is shut off and the vent doors are routing the air in the proper directions.

This is on my mind today because I took a brief drive when the temperature was 97 degrees (F) with a heat index of 121 degrees F. I don't need more heating right now.

Even if I had to cheat and "hardwire" the vacuum to blast cold air out the dash vents, I'd do it at the moment.

I also have vacuum problems with the headlights: When the car is running, the headlight doors won't drop. I found that out at dusk (and afterward!) coming home about 5 days ago. With the headlight doors up, forward illumination is extremely limited! :-)

It looks like parts stores carry the fundamental electronic part of the '67 Eldorado headlight switch. I assume it isn't hard to separate the electrical switch from the vacuum switch, clean up the vacuum control, and attach it to a new electrical switch. Is that a bad assumption?

So:
a) How can I buy Tim's book?
b) Can I cheat and manually "wire" up vacuum switches?
c) Do the easily available electrical 1967 Cadillac headlight switches fit the Eldorado as well?

Thanks!

[Glen]

I’m trying to remember which car it was that also had vacuum powered headlight doors.  I’m thinking it was a Pontiac.  There are new headlight switches for those cars.  I bought one for my 68 ELDO and it looks like the original.  I have not tried to install it. 

Remember the 67 and 68 headlight switches are one year only each.  The 68 turns on the parking lights with the headlights, 67 does not.      The part number for the 67 switch is 1995152.  Try a google search for that. 

[DeVille68]

Hi

Tim is here on the forum, he might reply as well. His number is:  864-348-7732

I think you could potentially "hardwire" your system. I would suggest that you check every vacuum hose. It is not hard to do but takes a few hours.
This is how I did it:
Luckily, I had access to an external vacuum pump so I did not have to run the engine for a vacuum source. I then attached the vacuum storage tank to the pump and added a tee at the outlet along with a vacuum gauge. Then I added a long vacuum hose along with various fitting to the other tee connection. With this long line of "vacuum source" I would go to each start of a line and connect my "vacuum source" to it. Then I would switch off the vacuum pump and check the reading of the gauge. If it dropped I knew I had a leak. Otherwise the vacuum will remain absolutely steady.

So you might add a tee to the vacuum tank and add a gauge, then route the outlet of the tank to a vacuum line you want to check, for example the line to the defrost actuator. Disconnect this line at the start (in-dash unit) (I think it is blue) and connect it to your "vacuum source line". Then switch off the engine or disconnect the vacuum tank from the engine and watch your gauge. If it drops you have a leaky actuator.

My actuators were all good but I had to snip an inch of some of the lines to get a proper seal on the nipple. My source of vacuum leaks were the two rotary valves (in dash unit and power servo).

Best regards,
Nicolas

[67_Eldo]

NAPA says they have that (electrical) headlight switch (1995152) in stock for $20 so I'll go down and find out tomorrow.

I found a "Gabriel Air Shock" 1/8" hose kit at Autozone so I'll use that to help check (and reroute) the vacuum. I tried my little hand vacuum, brake-bleeding pump to see if it would generate enough vacuum to move things like AC vents or headlight covers, but it doesn't. So I think I'll grab a vacuum pump from Harbor Freight and try that.

Gerald's Cadillacs site has an excellent description of renewing the rotary valve in the Power Servo (http://www.eldorado-seville.com/files/tag-vacuum-hoses.php). I assume that the rotary valve for the dash control uses pretty much the same approach.

Thanks!

[cadman56]

I'll stick my nose into this since I restored a 67 Eldo in the early 80's.  All I had was the factory shop manual to work from but it was enough to get every system working as new.
The headlight switch NAPA has will not have the vacuum valve on it.  Does you car have the auto on headlight system?  If so you have a much more complicated system to work with.
I found most vacuum problems with the climate control were due to dirt in the ports of all the control valves that rotate.  I took mine apart and cleaned them after doing a 'figure 8' with them on a piece of fine sand paper that I placed on a true flat surface.  They tend to warp.  I reassembled with a fine coat of silicone grease.
The dash is a pain in the *(). 
Good luck. 

["Cadillac Kid" Greg Surfas 15364]

This looks like what you want.

http://www.caddydaddy.com/shop-parts/switch/headlight/1967-cadillac-headlight-switch-eldorado-only-nos-free-shipping-in-the-us

Greg Surfas

[67_Eldo]

I'm hoping that I can clean up and use the existing vacuum valve on the headlight switch and then attach it to the new electrical switch. The existing electrical switch works, but it has dead spots in the dash-lighting rheostat. I'm doing lots of electrical work anyway -- installing relays to take over the high-current-handling duties in the old electrical system -- so I figured I might as well replace the electrical switch for $20 while I'm in there. The new switch will then run to a pair of relays that will handle the halogen headlights I intend to substitute for the existing sealed beams.

Thankfully I do not have the Twilight Sentinel (or power door locks), so my vacuum circuit is relatively simple.

I messed around with the headlight doors yesterday. Both of my actuators are OK, but the headlight vacuum tank holds no vacuum and the vacuum switch doesn't seem to work. The moment I switch the ignition off, the headlight doors drop like stones.

On the other hand, when the car is running, the headlight doors don't drop when I turn on the lights -- I discovered this problem on the highway at night a week ago -- so I temporarily closed off all the vacuum lines to the headlight doors so I can drive in the dark.

The instrument panel is intimidating, particularly with the left "Climate Control" vent blocking access to some under-dash pieces. I'm tempted to unbolt the bigger dash frame (or, officially, "bezel") because it looks like pulling that frame forward a little bit could make life easier. But I can't find instructions on bezel removal in either the shop manual or in the Fisher Body book. I'm therefore reluctant to mess with the main bezel infrastructure because loosening those big bolts may result in ugly unintended consequences!

Once I can pull all the vacuum switches I can find, I'll clean them all out using the method you describe. As far as I can tell, none of them are working properly right now (although there are probably many other vacuum leaks in the hoses and connections).

Greg: Yipes! I'd rather not spend $362 on a complete switch if I can reuse the current one. However, if my current switch is too far gone ….

Thanks!

[TJ Hopland]

You checked the tank on its own?  A lot of time on old stuff its been the check valve and not the tank itself.    Newer especially Ford for some reason that used the 'soup' cans into the 90's the tanks do seem to rust out.    If the space works out these seem like a well made tank and includes some fittings and the check valve. 

https://www.summitracing.com/parts/sum-g1464

[67_Eldo]

That's a good point: I didn't check the tank on its own. I just checked the tank input, right behind the left headlight.

I need to check the check valve.

Thanks!

[Glen]

I need to check the check valve.

Thanks!

Yes the check valve is the main suspect, it is in the vacuum T.  If you are going to do much vacuum work you should get a hand pump for testing. 

[67_Eldo]

I haven't yet solved the headlight-vacuum problem but I did find the disconnected vacuum hose that was messing up my Automatic Climate Control.

In the hustle and bustle of reworking some of the wiring, the vacuum hose slid off the "flying saucer" in the center of this photo. Once I freed the disconnected hose from the tangled mass of tubing and wires, I checked to see if it had hardened (it hadn't) and then pushed it all the way onto its vacuum connection.

Voila! The whole Climate Control system began working again. I didn't have to rebuild any switches or anything.

Now it is on to removing the instrument cluster, de-gunking the speedometer, cleaning the corrosion off of the indicator panels, repainting, and reinstalling.