IML: AutoTemp II Insight

[David Duricy <desotobravo@xxxxxxxxx>]

My '73 Imperial developed a vacuum leak that disabled
the blower switch. The AutoTemp system was otherwise
functional.

This week I hunted down the leak. I ended up replacing
the entire vacuum harness but to no avail. The hissing
sound seemed to move around inside the dash, and the
blower switch still didn't have enough vacuum to trip.

The problem turned out to be the vacuum transfer
switch. It controls the fresh air door, and is located
behind the glovebox.

The vacuum transfer switch has a pressed-in bottom
that seals a rubber disk. The bottom had popped out
and the disk disappeared. The switch was open to the
atmosphere, and would make an interesting hiss that
seemed to "move" as the AutoTemp went through its
motions.

Luckily, a broken switch from a parts car let me
repair the switch. The disk goes in pointy side down,
by the way.

Now the hiss was gone, but the fan would only come on
in DEF or HI DEF. After DEF or HI DEF had been
pressed, the fan would stay on if AUTO or HI AUTO were
pressed, but neither AUTO nor HI AUTO would trip the
fan if pressed first.

This is a symptom not listed in the service manual.

The cause turned out to be a faulty number one check
valve in my replacement vacuum harness. With a good,
used check valve installed, the fan came on just as it
should in all modes, and the AutoTemp is working
great.

Hope this information helps someone trying to diagnose
their AutoTemp. I'll post photographs of the repairs I
made later at my website.

Dave







 




		
__________________________________ 
Do you Yahoo!? 
Check out the new Yahoo! Front Page. 
www.yahoo.com 
 



-----------------  http://www.imperialclub.com  -----------------
This message was sent to you by the Imperial Mailing List. Please 
reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be 
shared with everyone. Private messages (and attachments) for the
Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx
To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm