Air Flow Weak without A/C
Thread Starter
Cruising
Joined: Jan 2014
Posts: 10
Likes: 0
From: Columbus GA
Air Flow Weak without A/C
73 Coupe, with factory air that has been upgraded by the PO. With just vent selected, the air flow (even at max) is very weak across all vents. However, with the A/C on air flow is very strong. Any ideas on what would make this happen? Issues with the temperature controls? Thank you for the help!
Burning Brakes
Joined: Dec 2008
Posts: 971
Likes: 45
From: Middlesex NJ
When you say upgraded by the PO ... do you mean its an aftermarket AC system like Vintage air or do you mean that it was converted to 134a?
If its an original system I don't know enough about them. You might need the AIM for your year car (Assembly manual) to check that all the controls (vacuum and cable) are configured or setup correctly. Then you have to figure out if they are working. That the AIM doesnt tell you and maybe someone on the forum can help diagnose that.
My 69 had vacuum controls for a heat only car but I believe the AC used the vacuum stuff as well to control the doors for where the air comes out of the various vents. My car had a cable (like an old style manual choke cable) on the other control wheel that moved a door to control the temp.
Many times weakness in flow is due to something (someone like mice) grabbing you jute backing off your carpet and stuffing it in the AC evaporator for a home. You could try removing the fan motor and looking around at the evaporator coils with one of those cheap flexible inspection cameras from harbor freight?
If its an original system I don't know enough about them. You might need the AIM for your year car (Assembly manual) to check that all the controls (vacuum and cable) are configured or setup correctly. Then you have to figure out if they are working. That the AIM doesnt tell you and maybe someone on the forum can help diagnose that.
My 69 had vacuum controls for a heat only car but I believe the AC used the vacuum stuff as well to control the doors for where the air comes out of the various vents. My car had a cable (like an old style manual choke cable) on the other control wheel that moved a door to control the temp.
Many times weakness in flow is due to something (someone like mice) grabbing you jute backing off your carpet and stuffing it in the AC evaporator for a home. You could try removing the fan motor and looking around at the evaporator coils with one of those cheap flexible inspection cameras from harbor freight?
Last edited by mysixtynine; Oct 22, 2014 at 01:20 PM. Reason: more info
Racer
Joined: Aug 2008
Posts: 413
Likes: 22
From: Justin TX
Do you still have the original HVAC box on the fire wall?
I would suspect that either a vacuum issue or blockage from a rodent infestation. There is a vent on the passenger side that opens with vacuum on my 69. It may not be operable and not allowing the fresh air intake to feed the vent system.
I put a Gen 4 Vintage Air in mine which does away with the vent options. so really need more info to diagnose what is going on.
I would suspect that either a vacuum issue or blockage from a rodent infestation. There is a vent on the passenger side that opens with vacuum on my 69. It may not be operable and not allowing the fresh air intake to feed the vent system.
I put a Gen 4 Vintage Air in mine which does away with the vent options. so really need more info to diagnose what is going on.
Thread Starter
Cruising
Joined: Jan 2014
Posts: 10
Likes: 0
From: Columbus GA
Do you still have the original HVAC box on the fire wall?
I would suspect that either a vacuum issue or blockage from a rodent infestation. There is a vent on the passenger side that opens with vacuum on my 69. It may not be operable and not allowing the fresh air intake to feed the vent system.
I put a Gen 4 Vintage Air in mine which does away with the vent options. so really need more info to diagnose what is going on.
I would suspect that either a vacuum issue or blockage from a rodent infestation. There is a vent on the passenger side that opens with vacuum on my 69. It may not be operable and not allowing the fresh air intake to feed the vent system.
I put a Gen 4 Vintage Air in mine which does away with the vent options. so really need more info to diagnose what is going on.
