Another poor airflow out the HVAC vents thread

[mlipmd]

I have a '90 ZR-1 which has developed a problem that I have researched on here and on the Corvette Forum and Googled and have yet to find a solution to, without ripping the whole interior of the car apart. I have cold AC, I have control over the vents (so I must have vacuum), I have control over the blower speed, but the airflow out of the vents is very poor. Setting the fan on "10" has the fan running at top speed but has the airflow I would expect out of "2". I have removed the blower motor and the evaporator is perfectly clean as is everything else I can see in there. I removed the blower motor controller to look into the other side of the evaporator and that area and as far as I can see is also clean in there. I attached a suction hose to my shop vac and sucked up in there as far as I could go, and nothing came out. I also put it up into the heater vents in the interior of the car and got nothing out. There must be a mouse or other rodent's nest in the ducts somewhere or total deterioration of the small amount of foam sealing the ducts, but where do I look next? Is there anyway to access the main duct system without removing everything under the passenger side dash, and if I did that, would I find where the problem is? I would hate to take that all apart and not find the problem.

[mlipmd]

I found part of the problem. I removed the grates over the center and passenger dash vents and got a good look in there. There were fragments of 30 year old foam which I sucked out with the shop vac and blew into there with the vac on blower, alternating a couple of times. I wouldn't say that totally fixed the problem but it made it a lot better - I can actually feel air blowing on my face now, much more than before. So I doubt I have a rodent's nest in there, it's just partially blocked with old deteriorated dried out GM foam.
The 12V feed to the blower motor itself and to the speed controller both seem normal, at 13.9V with the engine running, so I don't think there's a problem there.
I am trying to upload a short video of the fan motor running but I can't figure out how to do it here. It's not silent, possibly is making a low volume whistling/whining or scraping noise. While it works, maybe at 30 years old it's tired and needs replacing for more oomph. Maybe if I take it out again I could lube it but that would probably be a temporary fix.
Before digging into the interior and dash, I may invest $25-30 on a new blower motor to see if that helps even more.

[GOLDCYLON]

https://www.zr1.net/forum/showthread...ghlight=colder


Replace the 30 plus year old blower motor and while you are there block the vertical gap if it exists

[mlipmd]

The other thing about the foam is, I have no idea if that comes from the sealing of the various doors to direct the airflow, or if it comes from where the ducts join to one another, where, if that is the case, there could possibly be air leaks out of those areas into below the dash, resulting in poor airflow out of the vent outlets.

[Corvette95]

When I had the heater box out on mine, all the foam surrounding the firewall was deteriorated. When I re-installed I used Butyl tape all around the split cases and firewall. It helped mine, plus new blower and Haibeck mod.