1979 CDV High blower speed intermittent

[fasted55]

Hi.  The high blower speed works intermittently.  I have installed a new blower motor as they are inexpensive.  The blower resistor is fine.  The climate control in the center dash works fine except for the intermittent nature of the high speed blower.  I have cleaned up the terminals that I can access (blower motor ground to chassis, blower motor terminals, blower resistor terminals, engine compartment firewall connector).  I have not tried to gain access to the under dash connections (back of climate control, the ATC programmer, the inside firewall connector).   One fact that makes me suspect a high resistance somewhere in the circuit is the fact that if I remove the connector to the blower resistor and reconnect it I can usually make the high speed come on and sometimes leaving this connector unplugged the high speed comes on.  At least until I turn off the car and then I have to repeat the disconnect/ connect routine.  I have sprayed contact cleaner into the climate control (off, economy, AC low, auto, AC high, defroster) but I suspect the wiper and contacts are under a cover.  I have seen a YouTube video that shows if you take the glove box liner out you can at least see the ATC programmer.  Any ideas or shortcuts before I tear into the dash?  I really do not want to have to remove the center vents to take the dash apart because I just know I will break them.  Thanks for reading.  Ed

[bcroe]

The high blower setting runs enough current to sometimes burn out
connections.  Unfortunately with Climate Control that current runs
right through the dash circuitry; the problem may be there.  You will
have to track down the fault and do repairs.  I wrote an article in the
Self Starter a decade ago about how to add the type relay in non CC
cars, to keep the high speed currents away from the CC dash controls. 
Bruce Roe

[cadillactim]

Check the blower relay and the back of the dash control where the harness plugs into it. Very common overheat areas on 1977-80 models that cause melting of plastic at terminals.

Tim

[fasted55]

Bruce, Tim, thanks for taking the time to reply.  I should have mentioned in my initial post that I have rewired the fuse block with a new relay as the fuse block terminals for the relay had indeed overheated at some point in the life of the car.  I will check the wiring again as it's easy and probably buy a new relay as they're inexpensive.  I do have a few additional questions, two specifically for Tim since he is an expert at reconditioning the climate control (i.e. his own web page).  Q1: Am I correct in that the wiper contacts of the climate control will not receive contact cleaner if I just spray it in from the front slider area (i.e. they're covered)?  Q2:  Is it safe to assume the climate control is NOT faulty as it does all it's functions correctly?  Q3: How do you get the center vents out?  Do the vents have posts on the sides that fit into holes or do the vents clip onto posts and have horseshoe shaped female clips?  Q4: Do both sides of the vents need to be disconnected simultaneously or can you pop one side then the other?  And if I break one trying to get them out does anyone have spares for sale ?      Thanks and regards, Ed

[cadillactim]

Ed

The sliding contacts will not get much spray through the slit because they are toward the back of the controller.

To remove the vents you will see a slotted pin on the inside of the outermost vent slots (2 pins per vent). Take a small screwdriver and pull each pin toward the center of the vent to release the vent from the housing. What I do is do one side at a time. Pull in on one pin while gently prying the same side out a little. The do the other side and vent will come out.

You can still have a problem with the programmer blower sliding contacts. You can use spray on that but you will need to remove the programmer cover to be able to spray it. (The blower contacts are on the left side of programmer).

Make sure the blower resistor connections are clean.

Remove the dash controller and check for burnt connections. Once the controller is out you can use spray on the contacts since you can get to them then.

Tim

["Cadillac Kid" Greg Surfas 15364]

Ed,
When you pull the center outlets out you have acess to tow of the several screws that hold the center dash cover in place.  Once the cover is off you have ready access to the screws holding the AC control head in place.  Yopu can pull it forward, disconnect the vacuum and electrical plugs and you then have good access to the sliding contacts.

The answer is yes the replacements are available albeit costly.  Knowing how easily they are broken in the removal process ( I bought the Kent Moore tool for R & R and have not broken any since) I bought a few of them a few years back when you could still get them through the dealer.
Greg Surfas

[fasted55]

Tim and Greg,
Thank you for the pointers.  As the weather warms up here in Phoenix, the need to get my high speed blower circuitry debugged increases in priority.  Although whenever faced with something that involves a dive into tight quarters like the dashboard I tend to procrastinate and do just about any other chore than the one that should be my top priority.
Thanks and regards, Ed