AIR CONDITIONER ONLY BLOWS OUT DEFROSTER

Can anyone help with an air conditioning problem...the air comes out only on defrost...however, occasionally it will start working correctly.   Anyone have any suggestions to the problem?   Is this system vacuum or electrical?   This is a 1996 corvette convertible.  

to start with .. .do you know where your RPO tag is... look at it.. see if you have a manual system C60 or the automatic system C68


if you don't have function...  you will want to check the vacuum system....  here is a partial picture of it...  you will have to open this image in a new window to see the whole thing..   see item 18.. its up in front of the left front tire... there are vacuum hoses to it...  that come from item 24 the check valve...   you could have a vacuum leak in the hoses to the cruise control also



the problem you are having is probably vacuum...  

most of the rubber sections of the vacuum hose are 5/32    there is some 7/32 vacuum hose.. and some 3/32

please.. use some wire cutters to cut the side of the rubber hose from the hose barbs.. then peal it off.. cut a matching length and install ONE piece at a TIME.

i normally use a brake bleeder kit vacuum pump  to supply vacuum to various sections of the vacuum system. pinching it off with a tiny pair of long nose vice grip pliers.. or just some long nose pilers..  just enough to pinch the hose .. not enough to damage it..  only on the rubber sections..

 

I AM HAVING THE SAME PROMBLEM WITH MY 1993. BUT I HAVE AUTO AIR C-68.
THE SHOP MANUAL SUGGEST TO DIRET MY ATTENTION TO THE PROGRAMER. IS THAT THE DIRECTION TO GO. AND IT ONLY BLOWS COLD AIR NO HEAT....  

programmer.. sure.. if you want to bypass diagnosis.. just start throwing expensive parts at it ...

you have 4 vacuum actuators ... 3 shown on this image...   please verify that these are all working full swing..  that the flapper doors they operate are free to move..



this view is looking from about the right front tire.. through an invisible firewall.

you can test them by operating the controls on the dash board..

i would think that item 9 in this image might be your problem.. it moves door 11.. giving you HOT or cold blended air..



#009 16124952 ACTUATOR. A/C Control. A/C Vacuum Control.
ACTUATOR,TEMP VLV(ACDelco #16124952). Required: 01
ACTUATOR,TEMP VLV(ACDelco #16124952). Required: AR
For: Y (1992-1996) (1992 - 1996).
For: Y A/C AUTO ELEC CONT(C68) (1990-1991) (1990 - 1991).

since you have the fully automatic design...     turn the key on without starting the engine...   find the AC controls panel..

push the OFF and the warmer buttons at the same time... hold them for 5 seconds or so.. until the WHOLE dash board lights up..  make sure that you DON'T have your foot on the brake pedal..    one of the displays in your car will start flashing codes...  write the whole code number down..      the warmer button might be an UP arrow..

this is the C68 control panel


the actuators are little motors that move the various doors.. they do wear out...
i don't see what i know as a programmer other than the dash control head..  

try holding the OFF button on the lower left..   and the up arrow to the right of the AUTO .. to access the various trouble codes..  

THANKS I WILL CHECK THIS OUT...THATS WHY I WROTE... I HATE THROWING PARTS AT A CAR....