'69 Eldorado...Help With No Heat and Dash Control Problem...

[STDog]

From the manual.....the vacuum leakage plug is not used on the standard system, is a small, rivet shaped, porous-metal plug located in the end of a purple hose at the air inlet actuator in the right hand shroud side. Its function is to give positive leakdown of the system vacuum when the car is not operated.

Yes, all works correctly when bypassing the T.V.V., temp control, discharge and fan speed.

That sure sound like about 20 second to leak down and open the master switch.
The fact that it works (except for the delayed turn on) correctly when buy passing those 2 parts really makes me think it there.

Never thought I'd need a hair dryer, don't have one. One more tool wont hurt right?

I'd borrow one from a female in your life 

Sounds like you have a "fair weather" car like me! 

Not quite. It was my daily driver until 2007 (and my be again soon).
95+ summer heat and the wonderful Mississippi humidity.
Plenty of below freezing morning/evenings in the winter too.
(like yesterday morning  ) I've got a little 12 heater for a defroster. 

[Glen]

My interpretation of the A B C in regard to the power servo is just establishing points along its rotation. Point A is one quarter of the rotation, point B is at the halfway point and C is three quarters of the way.  This is in reference to the amount of travel of the power servo, not quarters of a full circle.  But you probably figured all that out by now. 

I did bypass the T.V.V. yesterday and the system worked having direct vacuum to the master switch. Its the other purple line from port 2 at the servo that doesn't supply sufficient vacuum to turn on the master switch or if its even supposed to in low, auto or hi?

The power servo is not concerned with low auto or high, it is only concerned with A/C, heat or somewhere in between.  It does provide the vacuum to the master switch for immediate turn on when on the A/C half of the stroke. 

Knowing where the power servo is will help.  If your problem occurs when the power servo is between max A/C and point B then you should check to see if you have a leak in the hoses on port 1 and 3.  A leak in either or both of those hoses could reduce the vacuum to a level too low to operate the master switch. 

When the power servo is in the heat half of the stroke port 2 becomes a connection to pass vacuum from the master switch (coming from the TVV) on to the outside recirc. air actuator.  A leak on that line could also cause the master switch to drop out. 

I hope all this is helping and I’m not confusing the situation.

Glen

[STDog]

My interpretation of the A B C in regard to the power servo is just establishing points along its rotation. Point A is one quarter of the rotation, point B is at the halfway point and C is three quarters of the way.  This is in reference to the amount of travel of the power servo, not quarters of a full circle.  But you probably figured all that out by now. 

that makes sense.

The power servo is not concerned with low auto or high, it is only concerned with A/C, heat or somewhere in between.  It does provide the vacuum to the master switch for immediate turn on when on the A/C half of the stroke. 

Doesn't it also control the fan speed in auto? Or is something else moving the wiper for the speed control switch?
(listed as part of the power servo in the schematic)

When the power servo is in the heat half of the stroke port 2 becomes a connection to pass vacuum from the master switch (coming from the TVV) on to the outside recirc. air actuator.  A leak on that line could also cause the master switch to drop out. 

I looks like the TVV isn't supplying vacuum to to the master switch (to be passed to the port 2 and the recirc. actuator).
When he bypassed the TVV, then he get vacuum to the master and the system functions.

I'm not convinced the temperature differentials are enough for it to enter MAX AC mode.


I guess if he had several vacuum pumps he could apply vacuum to the the master switch on the line from the TVV and vacuum to the control head input,port 1(engine vacuum could me used for this).

Then apply vacuum to the power servo and check to see how it behaves as it goes thrpough the range, looking for leaks.

[69eldo]

That does make sense, now I know my A, B, C's! 

Regarding port #2 in heat mode, it actually receives vacuum from the master switch rather than supplying it? I was wondering why they refer to it as T.V.V. "input" in the manual. That makes sense.

When I bypass the T.V.V. and send the vacuum source direct to the master switch it does not drop out, it stays working. Does this mean I do not have a leak there?     

Thanks again guys! I'll do some more digging on Sunday. Back to work today, no more tinkering for a few.

Grant

["Cadillac Kid" Greg Surfas 15364]

Greg,

Again, no cables and no programmer with this type of system. Its all vacuum and electrical.

Grant

Grant, then you should have a multi port vvacuum valve on the back side of your in dash control head.  Is that correct?
Greg

[STDog]

Grant, then you should have a multi port vvacuum valve on the back side of your in dash control head.  Is that correct?

Greg, yeah. The diagrams he posted show it too.
http://www.cadillaclasalleclub.org/forum/index.php/topic,103933.msg125133.html#msg125133
http://www.cadillaclasalleclub.org/forum/index.php/topic,103933.msg125134.html#msg125134

["Cadillac Kid" Greg Surfas 15364]

Greg,


The problem that I see is.....I don't seem to be getting vacuum to the master switch in low, auto or hi.

Thanks,
Grant         

Grant,
I think my brain is finally up to speed. Was running a few Hertz slow.  If the above is still true, the suspect would be the vacuum valve on the control head, or again, vacuum lines someplace.
To eliminate the control head check the ports in the 5 manual positions and verify the opening/closing sequence is as shown on the upper portion of figurfigure.  At this time for purposes of diagnosis I would also bypass the vacuum delay relay.  Once we have everything in sync. we can re activate that feature.
It seems that 1969 was another of the myriad steps in the design change sequences in the development of ATC.  I apologize, but this was an intirinterim I haven't run into before.
Greg

[STDog]

It seems that 1969 was another of the myriad steps in the design change sequences in the development of ATC.  I apologize, but this was an intirinterim I haven't run into before.

Isn't progress fun

Looking at the setup it's 95% the same as the 70 system. The '70 doesn't have the master switch, TVV, or delay relay, but the rest seams the same. I need to go look at the '68 now and see what all changed. I'm thinking they kept a few of the '68 features in '69 and then realized they weren't needed.

I need to figure out both the '69 and '70 as I was hoping to use parts from a '69 on my '70.



Grant,
Earlier in the thread you implied that you recently changed the TVV/water valve. Is that correct?

["Cadillac Kid" Greg Surfas 15364]

Thomas,
You've got the numbers just about right. 5% difference between 69 and 70. Extrapolate that between 1964 when ATC was introduced and 1971 when it essentially reached the final edition of a vacuum/ electric control system is about 40%.  That is the relative  change with the fan, compressor, evaporator, TXV, condenser and (basic) PA remaining relatively unchanged.  It was great progress in an era when transistor radios were state of the art, and a "hand held" calculator that could add, subtract, multiply and divide cost "only $300.00 and weighed about one pound.  Everything is relative, progress in particular.
Greg

[69eldo]

Grant,
Earlier in the thread you implied that you recently changed the TVV/water valve. Is that correct?

Yes, I did put a new nos control valve on the car which took care of the "no heat" problem. This morning I contacted the gentleman that I purchased the valve from and explained the T.V.V. was not allowing vacuum to pass through it when hot. He said that it was probably a bad part and would send me out another. Hopefully a properly working T.V.V. will take care of it.

Grant 

[69eldo]

Grant,
I think my brain is finally up to speed. Was running a few Hertz slow.  If the above is still true, the suspect would be the vacuum valve on the control head, or again, vacuum lines someplace.
To eliminate the control head check the ports in the 5 manual positions and verify the opening/closing sequence is as shown on the upper portion of figurfigure.  At this time for purposes of diagnosis I would also bypass the vacuum delay relay.  Once we have everything in sync. we can re activate that feature.
It seems that 1969 was another of the myriad steps in the design change sequences in the development of ATC.  I apologize, but this was an intirinterim I haven't run into before.
Greg

No problem Greg, I sure appreciate all of your help thus far!

The vacuum delay relay is currently bypassed. I think that I'll wait to do any further testing until I install the 2nd new control valve with a working T.V.V. and then see where I'm at.

Thanks,
Grant

[STDog]

The vacuum delay relay is currently bypassed. I think that I'll wait to do any further testing until I install the 2nd new control valve with a working T.V.V. and then see where I'm at.

Have you tried to locate a replacement delay relay?

If you can't find one, you could use normal delay valves in series to get the time right.
http://en.wikipedia.org/wiki/Vacuum_delay_valve

Not sure you need the full 45 seconds. 40 would probably be close enough (two 20sec valves)

[69eldo]

No, I haven't looked into a new delay relay yet. Actually, I'm not sure that its even bad? Not sure how to go about properly testing it to know for sure that its not working correctly. I'll have to look up the part number to see if there's a new one available somewhere.

Thanks for that link!

Grant 

[Glen]

The power servo is not concerned with low auto or high, it is only concerned with A/C, heat or somewhere in between.  It does provide the vacuum to the master switch for immediate turn on when on the A/C half of the stroke. 

Doesn't it also control the fan speed in auto? Or is something else moving the wiper for the speed control switch?
(listed as part of the power servo in the schematic)

Sorry for the confusion, I was talking about the vacuum system only.  The power servo does three things:
1)   Operates the vacuum valves to operate duct doors turn on/off water valve etc.
2)   Controls fan speed
3)   Moves temperature door to mix cool air from the A/C evaporator and reheated air from the heater core. 

I looks like the TVV isn't supplying vacuum to to the master switch (to be passed to the port 2 and the recirc. actuator).
When he bypassed the TVV, then he get vacuum to the master and the system functions.

Agreed, I was referring to normal operation. 

I'm not convinced the temperature differentials are enough for it to enter MAX AC mode.

I guess if he had several vacuum pumps he could apply vacuum to the the master switch on the line from the TVV and vacuum to the control head input,port 1(engine vacuum could me used for this).

Then apply vacuum to the power servo and check to see how it behaves as it goes thrpough the range, looking for leaks.

This is where having one of those hand vacuum pumps comes in handy.  They are almost a requirement for these cars that use a lot of vacuum operated stuff.   

Grant,
It does sound like the TVV is bad.  If you still have problems after that you may have leaks somewhere.  My concern is based on the thought that with the TVV bypassed the master switch could be getting a greater “volume of vacuum” (for the lack of a better term) that will mask small leaks.  The restriction of the TVV may cause the problem to reoccur.  But I hope not. 

You may want to check the TVV by attaching vacuum hoses and putting it in a pan of water on the stove.  As the water is heated the valve should open and you can blow through it.  With a thermometer in the water you can see at what temperature it opens.  As a safety thing, keep it off the bottom so it is not heated directly by the heating element. 

Glen

[69eldo]

I received my new replacement heater control valve yesterday and just installed it. The system seems to be working perfectly now in all heat modes. I now have full vacuum running through the T.V.V., the fan speeds, temp dial and air distribution all work like they should. 

I was able to find an nos delay relay and ambient sensor, both are on the way. After installing them I'll see if that changes anything. Hopefully this will be the end of this chapter!

Grant

 

   

[STDog]

I suspect the ambient sensor is fine.

Might I inquire where you located the delay relay?

[69eldo]

The delay relay I found at Chicago Auto Parts, the first place I called. There were two others that showed it, but I didn't call them to confirm. Here's the info on the other two.....

GM part #3514732

Llewelyn Obsolete GM Parts, CA.....818-363-5094

Collectors Auto Supply, WA.....800-414-4462

[69eldo]

I installed the new delay relay today and its working just fine. It delays vacuum to the T.V.V. for a short time and then lets vacuum pass through it to the T.V.V. and on to the master switch. I still need to have the a/c topped off and then hopefully that will be it!

Thanks to all that helped along the way!