1978 heating/air flow is low

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S

sjckn

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May 4, 2020
Thunderbird Year
1978
hello, I'm new to this forum. Have 1978 diamond jubilee w/tops. Very little air flow comes out of the vents even when blower is on high. The air that does come out is always warm.
I don't want to look into getting the AC working until I get this figured out. Seems like the blend door might be stuck. Is there a good way to troubleshoot? Thanks
Scott
 
All the vacuum lines and doors are usually located behind the glove box. Take out the glove box and start inspecting things around there first
 
Took the glove box out and inspected the vacuum lines and motors. The door for the inside/outside air seems to works fine. The selector for vents/floor/defrost seem to work ok as air flow gets directed as it should. Just low air flow. Barely noticeable. Fan speed varies ok in different positions. Maybe blower or evaporator core clogged? don't know if I can check those without tearing a lot apart - which I am not too keen on doing. May have to live with.
 
Sounds like something might be clogging or plugging up the vents. The fan works fine in low, medium, high speeds? Try different places like floor vent, dash vent, defroster vent. Does it come out slow on all of them? Does it have an air control on or by the fan & heater switch? sometimes you have to slide the air or vent control back or forth to get more air flow
 
Fan seems to work on all speeds. The fan is not making any unusual noises. Air flow comes out slow on each - floor, defrost and dash.
I'll try working the levers a bit to see if it changes. I know that the car must have sat for some time before I got it as I had to replace the gas tank due to internal corrosion, change the carb and all of the fluids.
 
Some critter might've gotten in and made a nest in your duct work. See if you can remove the motor and inspect the duct work. Or get a portable air compressor and blow them out with a nozzle
 
Might also be a bad actuator valve not opening up the doors. If you can find or see any little arms coming out or around the duct work by the vacuum hoses twist them back and forth to make sure the doors aren't stuck and see if any more air comes out
 
OK Thanks. I appreciate the help. I'll have some time this weekend to get into it again.
 
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