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NEED HELP!! AC only blows to the floor.

Mikez 81 Vette

New member
Joined
Mar 15, 2007
Messages
1
Location
IOWA
Corvette
1981 Black on Black C3
I have a great car that is a joy to drive, but in the summer when I run the ac it only blows to the floor, It keeps your feet cool but everything else sweats. Is there an easy way to get to the little door that controls the direction of the air flow? I think it's stuck (how I do not know). I can hear the vacuum change when I change the slide the from ac to floor to defrost. (It did work about two years ago).
Thanks, Mike
 

Peer81

Well-known member
Joined
May 21, 2003
Messages
2,497
Location
Netherlands
Corvette
'81 Black
Hello Mike,

The easiest way to get to your ducking and the ac stuff is getting your complete dash off and go from there. And when your there, check the entire ducking and reseal it! Most of the connections are poor and you loose much of the airflow. The door you need to check is next to the big heater core box.

Greetings Peter.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
I have a great car that is a joy to drive, but in the summer when I run the ac it only blows to the floor, It keeps your feet cool but everything else sweats. Is there an easy way to get to the little door that controls the direction of the air flow? I think it's stuck (how I do not know). I can hear the vacuum change when I change the slide the from ac to floor to defrost. (It did work about two years ago).
Thanks, Mike
I'd bet you have a vacuum leak under the hood somewhere in the small lines, possibly a one way check valve is leaking or someone routed something wrong after doing engine work!! Another possibility is a cracked line around the Heat,A/C control!!:upthumbs
 

Peer81

Well-known member
Joined
May 21, 2003
Messages
2,497
Location
Netherlands
Corvette
'81 Black
Good point Junkie :D
If there is no vacuum in the system it will stick in the same position!
The main vacuum source for the ventilation system should be somewhere behind your timing. Just like Junkie says, trace the small vacuum lines first and go from there.

Groeten Peter.
 

XLR8

Gone but not forgotten
Joined
Jun 23, 2004
Messages
6,662
Location
Mississippi Gulf Coast
Corvette
2003 AE Convertible, 1998 LCRM Convertible
I'm not familiar with C3's but I had an issue at one time with my C4 in which it suddenly began blowing through the defroster vent only and I couldn't turn off the heat. My mechanic replaced the vacuum switch (nice guy - that was one of those freebies "don't worry, catch you next time" he sometimes gave me).

Fixed it right up.
:w Jane Ann
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
I'm not familiar with C3's but I had an issue at one time with my C4 in which it suddenly began blowing through the defroster vent only and I couldn't turn off the heat. My mechanic replaced the vacuum switch (nice guy - that was one of those freebies "don't worry, catch you next time" he sometimes gave me).

Fixed it right up.
:w Jane Ann
Yeah,C3's have the same type Vacuum switch's,just a little different!!! There Cheep $2.00-$6.00 :upthumbs
 

c3cvte

Active member
Joined
Feb 23, 2007
Messages
37
Location
Olympia Washington
Corvette
1972 Stingray
Maybe find the vacuum line that goes to the vent doors and hook it up to a differnt vacuum line that you now that works. Atleast you could see if that operates it.....cheap diagnostic.
 

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