1970 Climate control ???????

[Bill Balkie 24172]

Hello ,
    It got up to 72° here in South Jersey today so when I got home from work I decided to take my car for a ride. I set  the climate control to 65° and selected Auto for the position.I got zero response coming out of the dash vents. Set the selector to vent and fresh air Started blowing out of the dash vents . Set the selector to fog and air came out of the top Dash vents. Set the selector to ice and hot air came blowing out of the top Dash vents. Set the selector back to Auto and got zero response. Set the selected to high auto and got zero response. After about 15 minutes cool air started blowing out of the dash vents . Set the selector to high and cool air came out at a higher rate. Set the selector back to Auto and the temperature control up to 80 and hot air came out of the heating vents. Set the temperature control back to 65 and cool air came out of the dash vents. At this point I felt the system was working properly. My question is why did it take 15 minutes to work properly . Is there something I should addressing . I would have to think when the cars were new the system responded instantly.

         Bill

[Cadman-iac]

Bill, it's an age thing. I have noticed that when I've left a vehicle sitting for some time. I think it's the glue used to hold the foam insulation/sound deadening in place on the mix and the mode doors. That stuff gets a little gooey and if it's sitting with the door closed, or open, and it's up against the duct or whatever in there, they tend to hang up until either there's enough vacuum force or  heat, which ever, to overcome the adhesive in the foam.
If it's all working fine after you used it for 10 to 15 minutes,  I'm sure that's all it is.
The fix for this is not so easy, as you have to take it all apart to get to the doors and replace the foam.

Rick

[cadillactim]

Could be your sensor in the dash pad is bad. It completes the fan ground circuit when the temperature in the car is about 75 degrees. There are two other ground circuits for the fan. A body  ground when in Vent, Fog, or Ice, and the heater turn on switch in the engine head. This prevents the fan from coming on in cold weather until the engine coolant is hot so cold air isn't blowing on your feet.

This is likely why it took a few minutes for your fan to come on in the Auto position. When the coolant was hot enough the fan came on. If your dash sensor was good the fan would have come on immediately in Auto.

That being said 72 degrees us close to that threshold voltage for the sensor to turn on the fan. I wouldn't fault the sensor unless the same thing happened when the temperature is in the upper 70s.

Tim

[Bill Balkie 24172]

Hello Tim ,
     Thank you very much for responding to my post . I did purchase your book a few months back and I have to tell you it is put together very professionally .  To me this is a very complex system . And I do appreciate your book and the job you did to make it easier to understand . However i have a lot of respect for someone who can trouble shoot a 50 year old system like this . Most people would open the hood look around and close the hood . I feel fortunate my system does work eventually. The water sensor that screws into the head . Is that part available ? Also the dash pad sensor is that part available . And if so where would you get them ?  And what is the going price for these two parts ?

        Bill

[cadillactim]

Bill

I have the dash sensor rebuilt for $50. I don't have any heater turn on switches for the cylinder head. The pop up on eBay from time to time.

Tim

[Cadman-iac]

I would like to add that I didn't take the ATC system into account when I offered a possible cause for the problem.  I'm used to the manual systems,  and here in the Arizona heat, it's usually a sticking door that's the cause.
Tim is definitely more experienced with these systems than I am, and would be a better source for information on them.
I hope you find the issue without much trouble.

Rick

[Bill Balkie 24172]

Hello Rick ,
      Thank you for your input. In a 50 year old car  I would not be surprised  if it is a door sticking . The fact the the front dash vents work and the fog and ice work and heat works those doors are eventually working . And that is not a bad thing . I am just not ready to tear into the car like that now . I think over the summer I will be using and exercising these components a little more frequently . Maybe next winter that would be a good project . I will learn a lot this summer .

     Bill

[Bill Balkie 24172]

Bill

I have the dash sensor rebuilt for $50. I don't have any heater turn on switches for the cylinder head. The pop up on eBay from time to time.
Hello Tim ,
      I would like to purchase the rebuilt sensor . Can you e mail me at wlb29@comcast.net  I can pay you using PayPal
     Thanks,
         Bill
Tim

[Cadman-iac]

Bill, I don't want to steer you wrong with ideas that may or may not be the problem.  When I approach these things, I try to find the simplest explanation for the problem first.
In the past I used to really dig in, expecting the worst, and usually after much searching and testing, I would find it was the simple thing that had been the cause in the first place. If only I had checked that first!
So now, my methodology has changed somewhat, and I pursue that simple cause/cure first, before I tear the car apart, and my advice reflects this as well. If I'm going to be wrong, at least I hope I'm not going to cause someone a lot of unnecessary work.
One thing I might add here is, if it is in fact a sticking mode door, I've noticed that a lot of times when it finally releases, it does so with a light thud as the door pops loose. That should be a clue if you happen to hear it.
  But I do hope that you find the problem without much difficulty.

Rick

[Bill Balkie 24172]

Bill, I don't want to steer you wrong with ideas that may or may not be the problem.  When I approach these things, I try to find the simplest explanation for the problem first.
In the past I used to really dig in, expecting the worst, and usually after much searching and testing, I would find it was the simple thing that had been the cause in the first place. If only I had checked that first!
So now, my methodology has changed somewhat, and I pursue that simple cause/cure first, before I tear the car apart, and my advice reflects this as well. If I'm going to be wrong, at least I hope I'm not going to cause someone a lot of unnecessary work.
One thing I might add here is, if it is in fact a sticking mode door, I've noticed that a lot of times when it finally releases, it does so with a light thud as the door pops loose. That should be a clue if you happen to hear it.
  But I do hope that you find the problem without much difficulty.

Rick

Rick ,
    That's good advice , that's why i am going to start with the engine coolant temp. sensor .Again I feel good that the system does work . Sometimes it is necessary to drive your car every day for awhile to exercise the system .

    Bill

[Jeff Rosansky CLC #28373]

Rick ,
    That's good advice , that's why i am going to start with the engine coolant temp. sensor .Again I feel good that the system does work . Sometimes it is necessary to drive your car every day for awhile to exercise the system .

    Bill

I believe that sensor just makes a system ground. To make things simple you should be able to just ground the wire to fool it. And/or check continuity between the wire and ground.
Jeff

[Bill Balkie 24172]

Hello Jeff ,
    Great idea .Thank you very much for your input.

    Bill

["Cadillac Kid" Greg Surfas 15364]

The heater turn on sensor in the passenger side cylinder head are available in quite a selection of "make" temperatures for a myriad  of applications. Typically those specified for our cars range from 90 to 120 degree turn on (when the contacts "make") temperatures. The actual delay time seems greater when you are waiting for cooling or heat, but if your connection to the sensor is good and it does "finally" turn on you can avoid spending the $45.00 for an NOS sensor.
Greg Surfas

[cadillacmike68]

^^ But that's only when the system is calling for heat. If the system is calling for cold air, then it should turn on almost instantly. 1970s have a purge that a few seconds when the system is initially turned on.

Now, if you are in that middle area, where the ambient temp is cool enough for the system to think it needs heat, then this can cause a delay.

[Cadillac Fleetwood]

Bill,
Do I recall that you had the instrument panel top off?  You may want to check the connection at the dash sensor to make sure it is tight.

-Charles Fares

[Bill Balkie 24172]

Hello  Charles ,
     You are right , I had it off to replace rhe radio Speakers . Charles if i remember correctly the only wire attached to the dash cap is the Radio Speaker wire . Anyting can happen but i do not think i  even touched that senser . The good part is its not that hard to get at . I purchased an extra dash senser from Tim just in case . I can ground out my heater switch  senser to see if thats OK. Good thinking by Jeff Rose .
Its always good to hear from you Charles .


     Bill

[Bill Balkie 24172]

I believe that sensor just makes a system ground. To make things simple you should be able to just ground the wire to fool it. And/or check continuity between the wire and ground.
Jeff
Hello Jeff ,
      I removed the wire from the heater switch sensor and grounded  the wire to the hood hinge . Stated the car and put the switch to auto and got blasted with air . switched it up to high and it responded with more air. turned the temperature up to 80 and the dash vents quickly shut off and the air came blowing out of the heat vent . Thank you for that tip . Looks like I need a heater switch sensor .  Thanks again for your help .
        Bill

[cadillactim]

Bill

I thought you said earlier that the system did come in after a few minutes. That sounds like the heater turn on switch is working.

Mailed your dash sensor out today.

Tim

[Bill Balkie 24172]

Hello Tim ,
    Thank you for sending the dash sensor . I might or might not need it but I am
Glad to get it .
    Tim if you read my post it takes at Liest  15 minutes for my system to respond in the auto setting .  After  15 minutes sometime longer  the system works OK .
    Today I pulled the wire off the heater sensor and the system responded as soon as the car started .  Why should it take 15 or more minutes for that heater sensor to kick in ? Do you think something is wrong with the heater sensor ?
    Bill

["Cadillac Kid" Greg Surfas 15364]

Bill,
I would wait until the weather in your neck of the woods warms up a bit.  If it still takes what you feel is too long pm me about a new sensor.
Greg Surfas