AutoTemp I (1968)

[Brad Hogg <roadhogg@xxxxxxx>]

If the 68 system has anything in common with the 74-78 system, that symptom
is quite common.  There is a vacuum switch that is turned on by hot wanter
from the engine.  On the 74078 cars it is located near the blower motor,
under the hood, near the firewall, close to the right fender.  The device
serves two purposes.  The device allows the ATC system to turn the hot water
on and off as needed and it also houses the vacuum switch that will hold the
ATC system off untill the engine reaches about 120 F.  When the water is
hot, the switch opens and allows the vacuum to be present at the ATC system.
There is another switch that turns the electrical on, this switch is
operated by the vacuum.

In the DEF position, this system is bypassed and the ATC will run in HI mode
at all times to clear the windshield.

Check for vacuum at this switch and at the soup can reservior under the
hood.  These systems do not employ magic and they can be repaired, often
easily with a little investment in  troubleshooting.

----- Original Message ----- 
From: "David Duricy" <desotobravo@xxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Thursday, July 01, 2004 4:14 PM
Subject: IML: AutoTemp I (1968)


My work on the 1968 Imperial Crown convertible has
gotten to the point where I am testing the AutoTemp.
The AutoTemp has an interesting problem.

I believe that the system was working correctly when I
bought the car, and was still working correctly when I
first re-started the AutoTemp today.

However, the servo began to make a grinding sound,
while I noticed that the system would not start on
"Auto" but would start on "Hi-Auto", "Def", and
"Hi-Def". After the system is on, pressing "Auto"
turns it off.

Pressing "Off" causes a buzzing sound, which I think
is the circuit breaker, and cuts the fan abrubtly and
leaves the A/C doors open.

I cannot hear the servo trying to park.

My bet is that corrosion has gummed the servo works,
causing the motor therein to jam, and thus trip the
breaker. Does this sound reasonable to those of you
who have worked on this system?

I'd like to open the servo box. Does anyone here have
experience with this style servo? I'm curious to know
how similar or disimilar it is to AutoTemp II.

Thank you for your insights!

Dave Duricy
1968 Imperial Crown (convertible)
1973 Imperial LeBaron
1950 DeSoto Custom (Visit DeSotoland.com!)