86 Air conditioning not flowing through vents

[Joecar]

So i noticed this when i turned my AC on during a hot day and i felt the air not going through the vents properly. Instead i felt air coming out from the passengers side underneath the dash. Any solutions?

[Stoffregen Motorsports]

Is it freezing over? If you let it sit for a while then start it back up, does it blow cold?

 

If it's not freezing over, you may have a loose duct or one of the flapper doors is stuck.

[Joecar]

2 minutes ago, Stoffregen Motorsports said:

Is it freezing over? If you let it sit for a while then start it back up, does it blow cold?

 

If it's not freezing over, you may have a loose duct or one of the flapper doors is stuck.

Does not blow cold cause i still have to recharge it with some refrigerant. How can i check to see if its loose?

[bottomwatcher]

My ducting has started to crumble. The plastic is brittle and what I have done is glue everything back to the shape is should be then glass over it with 6 ounce finishing fiberglass cloth and epoxy resin.

[Joecar]

1 hour ago, bottomwatcher said:

My ducting has started to crumble. The plastic is brittle and what I have done is glue everything back to the shape is should be then glass over it with 6 ounce finishing fiberglass cloth and epoxy resin.

How can i acess the ducts 

[Joecar]

Also i dont know if all that foam has anything to do with the problem

[720_Jeff]

That evap box should have clips, fastening the top to the bottom.  See the edge of the two pieces, where the foam is coming out, the squares molded into that edge are for a clip that holds the two pieces together.

 

Edited August 18, 2022 by 720_Jeff

[720_Jeff]

I knew there was a thread about this very style clip.  From the pictures, it looks larger than what the 720 would use, but who knows.  At least this gives you an idea what you are looking for.

 

 

[Joecar]

28 minutes ago, 720_Jeff said:

That evap box should have clips, fastening the top to the bottom.  See the edge of the two pieces, where the foam is coming out, the squares molded into that edge are for a clip that holds the two pieces together.

 

I took them off when i took the photo oops 

[bottomwatcher]

Clean out the box. You may find rodents have built a nest in there blocking airflow. I have had rats and mice do all kinds of havoc to my ventilation system including dying in there. My chevy pickup still gags you with rat piss smell when I turn on the heat. Can't get at all the ducting.

[NC85ST]

I can’t tell for sure, but it looks like some, if not all of this seal is missing. I know it was on mine and I replaced it with weather stripping. It made the flow, but that system is not great. Once you make sure the evaporator box is cleaned out and all of the clips back in place (I think it’s either 2 or 3 on the backside that are very difficult to get to) remove the fan and fan box to replace seal between the fan box and evaporator box.

[Stoffregen Motorsports]

All of my restorations get the HVAC boxes re-foamed. You can buy rolls of the foam at McMaster-Carr in different dimensions and different types. I can dig up the foam info if you like. I use wide sheets for the flap doors and thin strips for the seals between boxes and ducts.

 

Below are some pics of a restored HVAC system and the foam I use.

 

[Stoffregen Motorsports]

Here's the page - https://www.mcmaster.com/catalog/128/3949

[Joecar]

2 hours ago, NC85ST said:

I can’t tell for sure, but it looks like some, if not all of this seal is missing. I know it was on mine and I replaced it with weather stripping. It made the flow, but that system is not great. Once you make sure the evaporator box is cleaned out and all of the clips back in place (I think it’s either 2 or 3 on the backside that are very difficult to get to) remove the fan and fan box to replace seal between the fan box and evaporator box.

Yeah when i checked the strip of foam disintegrated so maybe thats the problem

[Joecar]

42 minutes ago, Stoffregen Motorsports said:

Here's the page - https://www.mcmaster.com/catalog/128/3949

Thanks ill be looking at this

[Thomas Perkins]

2 hours ago, Stoffregen Motorsports said:

All of my restorations get the HVAC boxes re-foamed. You can buy rolls of the foam at McMaster-Carr in different dimensions and different types. I can dig up the foam info if you like. I use wide sheets for the flap doors and thin strips for the seals between boxes and ducts.

 

Below are some pics of a restored HVAC system and the foam I use.

 

Wow,That look's like the best stuff to use.

[Thomas Perkins]

You know I got to throw my two cent in.The stuff Stoffregen-MotorSports has is probably the best.I put 3 heater cores in mine.Yes 3.Two came from Autozone with lifetime warranty,First one lasted 11 years.The next one lasted 5 years.Then when I took the last one back to Autozone,they were discontinued.They gave me my money back.Orielly's,Advance didn't have any.Looked on Ebay,Found the last one,exact same one as Autozone but 30 dollars more.It lasted just 3 years.Then it got ugly,looked everywhere and the only thing was a used one on Ebay from a friend.It looked real scary looking.So,I called up Jack,the pro that put my Jasper Engine in.He said he will get one and put it in.Then I said to myself,now I am going to have a high labor bill.Then he called back and said,he couldn't find a new one and he doesn't put used parts in.So he said he could put a brand new custom made heating and air system in and he has a restored Jeep Wagoneer with one he put in it.Also my A.C. compressor was bad too.I went and looked at it and it was awesome.So he hooked me up.All my Nissan heating and air is completely gone,I mean everything.My foam that sealed everything was dry rotted.I had a mouse nest in the blower motor box.The other heater cores didn't fit in the box good,had problems with the adjusters.The cable got bent,had to replace.Nissan had them then.Their are a zillion things to take off to get heater core out.Got to lift the dash up.When you do it 3 times,you get good at it.But never again.I have boxes of green scrub pads that I used to seal everything back then.It worked.Got them from Work.You get real creative when you own a 720.Here are some pictures of the last heater core that I installed in 2018.They get pin holes and fog up your windows.If your coolant over flow container gets low,check out your carpet.I did install gray carpet when I had the heater core out,it goes behind the core.Got rid of the black carpet.Made my inside more gray.It gets real humid here in Georgia.Even put a gray carpet over the dash and painted the door panels and side and back.I also used some door seal that worked. lot cooler after it sits in the sun all day. 

Edited August 18, 2022 by Thomas Perkins

[Joecar]

Can someone tell me where the clips are for this box before i just tear it out lol

[Joecar]

Its still in there so something is holding it

[NC85ST]

Those clips are used on all sides of the box. The 2 or 3 in the back are very hard to get to. Not much space to get your hand between the box and firewall. The left rear clip can be very difficult because of the trans tunnel. Go ahead and remove the fan box first, it makes it a little easier.

[Stoffregen Motorsports]

Yes, you remove the entire boxes from the firewall. You're not supposed to take them apart while still attached to the truck.

 

Not sure about the 720, but some HVAC boxes attach with fasteners accessible inside the engine bay.

[720_Jeff]

The evap inlet/outlet pipes go thru the firewall, otherwise all the fasteners are inside the cab.  I've taken a couple out at the junkyard, as I recall, there wasn't much to it.  There might be a screw that is not so easy to reach behind the evap somewhere.

Check out Charlie69 post
Posted June 24, 2020

 

[Thomas Perkins]

I had a new evaporator put in mine.Did not do any good.The air compressor was bad.A shop was going to put a new compressor in but the wrong one was sent and they told me that they wouldn't or couldn't find another one.So I got a custom made system.If you are looking for a compressor.Rock Auto has them,but you will have to get a new hose to fit it.My system uses the same one Rock Auto sells.But it didn't come from there.I checked out my part number and it matches Rock Auto's.All my hoses came in a kit.I had the exact same night mare as you Joecar.All that Nissan junk is gone from my 720.A very bad invention.I removed the clips on that box before and it was a job.When jack took all the Nissan stuff off,I let it stay with him.Here's a picture of my new control knobs.Everything under the dash has been replaced.The hole where the old heater core hoses came thru the firewall has  been closed with Dynamat,same thing I used when I replaced my carpet.That is the hose going to the compressor.

Edited August 20, 2022 by Thomas Perkins

[Joecar]

12 minutes ago, Thomas Perkins said:

I had a new evaporator put in mine.Did not do any good.The air compressor was bad.A shop was going to put a new compressor in but the wrong one was sent and they told me that they wouldn't or couldn't find another one.So I got a custom made system.If you are looking for a compressor.Rock Auto has them,but you will have to get a new hose to fit it.My system uses the same one Rock Auto sells.But it didn't come from there.I checked out my part number and it matches Rock Auto's.All my hoses came in a kit.I had the exact same night mare as you Joecar.All that Nissan junk is gone from my 720.A very bad invention.I removed the clips on that box before and it was a job.When jack took all the Nissan stuff off,I let it stay with him.Here's a picture of my new control knobs.Everything under the dash has been replaced.The hole where the old heater core hoses came thru the firewall has  been closed with Dynamat,same thing I used when I replaced my carpet.That is the hose going to the compressor.

I might have to do this cause im so lost on this mess lol.

[NC85ST]

You did find the one nut on the lower right hand corner of the box, right? It’s between the heater and evaporator box. I forgot about it. I just went and looked at my parts truck and found it. There is styrofoam in the evaporator box that can make it difficult to wiggle off. Disconnect the lines, under the hood, going to the evaporator, it should help get it out.