A/C Problems
Thread Starter
Heel & Toe
Joined: Sep 2009
Posts: 24
Likes: 0
A/C Problems
I have a 1980 L48 and everything works on the A/C, but all of a sudden the A/C won't blow through the vents. It only blows from the lower vent where the heater blows from. What could have gone wrong?
Thanks Kevin
Thanks Kevin
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Check the vacuum signal under the dash and at the switch.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
I wrote this up awhile back for this problem.
The problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Try pressing the 2 halves of the switch together.
The problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Try pressing the 2 halves of the switch together.
Thread Starter
Heel & Toe
Joined: Sep 2009
Posts: 24
Likes: 0
I found three small vacuum lines coming from the engine compartment going through the fire wall. They are colored white/green/black they all look to be in very good condition. Which one is for the A/C? Thanks Kevin
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Melting Slicks
Joined: Mar 2008
Posts: 2,023
Likes: 6
From: Austin Tx
The vacuum line that goes into the wiper valley, goes to the plenum door - this door opens to let fresh air into the plenum when on 'Max AC' - I don't think this is your problem.
Your problem appears to be the diverter that controls where the air, either hot or cold goes.
The diverter has 4 vacuum lines from the console control going to it - Tan and Pink control going to the upper vents, and Blue and Red control going to the lower. Follow these lines to the diverter, and make sure they are correctly connected
Also, you might want to take off the passenger dash pad, and move the H/C wheel back and forth and watch the cable that from the control panel, and see if it's moving the temp control.
Matt
Your problem appears to be the diverter that controls where the air, either hot or cold goes.
The diverter has 4 vacuum lines from the console control going to it - Tan and Pink control going to the upper vents, and Blue and Red control going to the lower. Follow these lines to the diverter, and make sure they are correctly connected
Also, you might want to take off the passenger dash pad, and move the H/C wheel back and forth and watch the cable that from the control panel, and see if it's moving the temp control.
Matt
Last edited by Mashman; Feb 18, 2010 at 05:43 PM.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
I wrote this up awhile back for this problem.
The problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Try pressing the 2 halves of the switch together.
The problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Try pressing the 2 halves of the switch together.
I especially vote for #2, switch has come apart.
Thread Starter
Heel & Toe
Joined: Sep 2009
Posts: 24
Likes: 0
What switch are you speak about? The lever that switches from Max to Norm or one under the dash. If one of the lines are broke where can I get a new line or what would I use to splice them together. Thanks Kevin
Thread Starter
Heel & Toe
Joined: Sep 2009
Posts: 24
Likes: 0
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
The switch is in the console attached directly to the selector for Vent/(A/C)/Heat/Defog.
I just remove the 1 front screw from a side console panel for access.
A piece of hose works great to replace part of a tube.
I just remove the 1 front screw from a side console panel for access.
A piece of hose works great to replace part of a tube.