HVAC DUCT INSULATION

[PATHFINDER99NI]

I’m looking at getting my AC up and running again and I want to make sure it works as efficiently as possible. To do that, I am going to install an electric fan, install insulation around the cat area, and I want to insulate the ducts. The air that blows through, blows warm, so I’m figuring the air is being head by the ambient air and the blend door needs adjustment.
On the topic of insulating the ducts, is there a thin spray insulation available or will I just have to wrap them in jute?

Thanks all!

[VStar650CL]

The intake for the HVAC system will be up in the cowl, usually on the opposite side from the wiper motor. So the cats and engine heat don't affect it as much as hot exterior sheet metal does. One of the dumbest things people do from an HVAC-efficiency standpoint is park under trees for years and let the cowl fill up with pine needles and debris. On some cars like gen2 Versas you can even cause a flood that way, from obstructed cowl drains. I don't think I'd mess with the cat shielding directly, that can change the airflow around the A/F sensors and actually cause codes (as can omitting OE heat shields). But extra insulation on the floorboards can't hurt. As far as duct insulation, there isn't a whole lot to insulate unless you want to cover the whole blower/intake assembly. I doubt that's worthwhile. The air isn't traveling long distances like it does in a house, and most USDM A/C's are intentionally very overpowered for the amount of cubic feet they're cooling. OE's know American drivers like their cold air cold and hot air hot.

[PATHFINDER99NI]

The intake for the HVAC system will be up in the cowl, usually on the opposite side from the wiper motor. So the cats and engine heat don't affect it as much as hot exterior sheet metal does. One of the dumbest things people do from an HVAC-efficiency standpoint is park under trees for years and let the cowl fill up with pine needles and debris. On some cars like gen2 Versas you can even cause a flood that way, from obstructed cowl drains. I don't think I'd mess with the cat shielding directly, that can change the airflow around the A/F sensors and actually cause codes (as can omitting OE heat shields). But extra insulation on the floorboards can't hurt. As far as duct insulation, there isn't a whole lot to insulate unless you want to cover the whole blower/intake assembly. I doubt that's worthwhile. The air isn't traveling long distances like it does in a house, and most USDM A/C's are intentionally very overpowered for the amount of cubic feet they're cooling. OE's know American drivers like their cold air cold and hot air hot.

Well since I’m getting hot air out of my dash vents, is it just the blend door not fully closing the hot side? It seems like that air should be much cooler.

I’m not touching the cats shielding at all, in fact I’m looking to see if there is insulation available to glue to the underside of the floorboard, seeing as it will be in the elements.

I appreciate the reply

[VStar650CL]

Well since I’m getting hot air out of my dash vents, is it just the blend door not fully closing the hot side? It seems like that air should be much cooler.

That's hard to judge from the info you've given, the cowl can get mighty hot from sitting in the sun. The A/C on our '13 Altie blows like the North Pole, but on a 100F sunny day it will take a good 8~10 minutes for it to chill all the hot sheet metal and start to blow arctic cold. There's really no getting around that, thermal mass is what it is. The evap will get hot too, along with the walls of the HVAC Unit, and since the oncoming air always travels through the evap regardless of temperature setting, that could take a long time to cool down with just airflow. You can probably separate how much of the thermal load is in the HVAC and how much is in the cowl by running an experiment with the recirc door open and closed under similar ambient conditions, to see how long it takes "just air" to drop the vent temp to outside ambient.