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Hot air coming into the cabin

lithiumus

lithiumus

Experienced Member
Joined
30 June 2004
Messages
1,088
Location
Toronto, Canada
I think this was mentioned somewhere before but I noticed that a lot of hot air comes into the cabin when the center console and audio components are not present.

It's been a while since I've driven my car but I noticed how much hot air comes into the cabin when driving. My climate control was turned off, in fact disconnected and none of the hot air was coming from the vents. It was coming in from behind the radio.

Just checking to see if this is normal or if I have some serious air leaking in from under the hood. I'll have to get a Type R hood duct and see if it makes a difference. If this is the norm, I can't imagine that audio compoenents would enjoy the added hot air...
 
Maybe your blower motor is not sealed tight against the front firewall and hot air from the radiator compartment is seeping in. With no radio or climate control to slow down this incoming hot air, you may be more sensitive to it?
 
Lithiumus where you been man?:eek:

or do you just lurk now, the legend is back.

but like they said I would think that your NSX was set for fresh air, then you disconnected it and its stuck in the fresh air mode.

if you reconnect it, turn it on and change to recycle cabin air, then disconnect it will def Keep it in the recycle air part.

or you can open the front hood and cover the intake for the blower motor
as to not let any air in.

hope this helps bro.

log into prime more often
 
wow I have not seen the stormtrooper avatar in quite some time.:smile:
 
LOL! I know it's been a while! With 3 kids all under the age of 5 it's hard to spend much time but I try to when I can. I'll be posting up some more stuff when I get back to working on my projects.

I'm postitive I set my climate control to recycle before I stored the car. In fact, none of the vents in the cabin have any air flow at all. The only hot air coming in was right around the sides of the blower unit.

The area areound the head init feels as though I had the climate set to max heat and fan set to the lowest setting. When the car is stationary, there is no hot air. Only at highway speeds. I'll have to get someone with me (besides my kids) to check the blower unit when cruising or drive so I can check the unit.

I can remember this phenomenon back when I first got the car but just assumed it was normal... I drove around a lot without a head unit when I was working on my first install.
 
also if you take the blower out there is a seal just like the rear taillights that leak, after years in the car I found mine fell apart when I removed it.

they fell on the ground as powder.

so I got some doublesided foam tape and made new one and it worked fine.
 
Hi jagtiger, well... after 2 years I still have this problem as I did not really drive it much the last 2 years but it's back on the road this year and after a recent drive I still noticed this so I still have to fix it. I still need a good passenger to sit with me to help me isolate the problem. Shawn's suggestion of removing the blower and checking the seal is a good one but I don't know if I want to take that on during the drive season but maybe when I store the car in the fall. I'll report back to this thread.
 
Hi Lith, thanks for the reply. Per Shawn, I took out the blower and replaced all the seals. After driving it for a couple of times, unfotunately the cabin heat is still there.

I was wondering if there's a way to disable the heater or the heat source?
 
Hey Jag. Thanks for keep us updated. Hmm must be something else. I drove the other day and felt the heat as well. Ive got a type r hood and im installing thenhood duct soon. Maybe that can rule out the heat from the rad, then it must be something else ie maybe where the coolant comes in for the heater.

So far it feels like radiant heat rarher than a blowing.

Did you remove the blower from the hood side? Ie not from the interior right?
 
Yes, i took out the blower from the front hood side. it wasnt difficult at all approx 1.5hrs including replacing the seals. The radiant heat is definitely coming underneath the dashboard. I suspect it is either caused by the heater core (?) under the dashboard or it could be like you said that the radiator heat is seeping into the cabin underneath the dash.

I also have a type r hood and also considering going to the radiator duct route to see if it eliminates the cabin issue.

Please keep us posted also if the radiator duct works to resolve the cabin heat issue. Thanks Lith
 
Last edited:
Ill let u know. I have my doubts though. I feel it must be the heater/evaporator since the heater core is inside it and is situated in the lower portion.

If thr heater core heats up the entire assembly and its radiating heat, then there is nothing we can do but i think it must be a leak in that unit as it opens up and seals from the bottom but its a real pain to get that unit out to check...
 
When I took out the blower unit out i noticed that there are heater coils underneath/inside the dash. Now it make sense to me that the radiant heat could have been leaking to the cabin somewhere.
 
I am new to this forum, thread and car. I just picked up a 1991 NSX and I noticed the heat coming in as well.
Remind me, doesn't there exist some sort of valve that keeps the hot water from flowing through the heater core? If that is in in place and working, it would seem to me that the core would be room temperature when water is not flowing. The heat I would suspect is coming from the heat off the back of the radiator, flowing up through the front compartment. Just my guess, but that is where I am starting.
Does anyone have a schematic of the heating and cooling system? I sure could use it.
Thanks a million.
 
I had the classic issue of heat coming into my cabin when driving at speed, even with A/C set to full cold. In my case, it was coming in the footwell. A very nice NSXCA member at the 2012 NSXPO showed me how to adjust the water valve cable under the hood vent valence (on the coolant pipe going into the firewall). In fact, he adjusted it right there at NSXPO and problem totally solved. Took all of about 10 seconds.

The issue is that over time, the cable leading to the heater control motor slips in the retaining clip, which creates slack, which means the water valve does not close completely and hot coolant circulates through the heater core- even when set to full cold. All he did was unclip the retainer, pull the slack out of the cable, and re-clip. Garrick, before you disassemble your HVAC, you should check this simple fix. BTW, your powdercoated covers are still going strong on my NSX. They are one of peoples' most-appreciated things about my NSX at car shows. :)
 
Hey Speedmaster, welcome! The more members working on the problem the better we are as a community in solving these issues and it will benefit everyone!

As suggested by Shawn, check the blower seals first. That is probably the largest firewall opening that needs to be sealed between the underhood area to the interior cabin. It's highly unlikely that there would be an air leak elsewhere in the firewall that would produce that much heat.

I think you are on the right track as there is supposed to be a valve according to the service manual (which you should download as soon as possible!). I have yet to understand its function but if it is what you say it is, it's highly likely that the heater core that is in the evaporator inside the center dash is heating up but the air vent is closed i.e. not blowing hot air and is just radiating heat inside the dash. Definitely something to look at if the valve is supposed to be closed. Will check the service manual and report back.
 
Honcho thanks for your input.What I couldn't figure out is my heater valve is already in the shut/close position (control cable is disconnected) and there still radiant heat coming underneath the dash? So it must be the heat from the radiator so... I went ahead and replaced all the foam seals around the blower per Shawn's recommendation but I can still feel the heat after 15 min of driving. There's no heat when AC is on.
 
Briank said:
The heater valve is not spring loaded so disconnecting the cable only disables control of it.
Click to expand...

Hi Brian, it in the close/shut position but I will put a zip tie just to be sure it stays in the close position. Thanks Ill keep you guys posted.
 
cant ignore this one, especially with the summer weather. Definitely hot air coming near the feet. So much text but no pics! Any diagrams of whats going on? Not that its that big of a deal, doesnt sound like a problem.
 
Speedmaster said:
I am new to this forum, thread and car. I just picked up a 1991 NSX and I noticed the heat coming in as well.
Remind me, doesn't there exist some sort of valve that keeps the hot water from flowing through the heater core? If that is in in place and working, it would seem to me that the core would be room temperature when water is not flowing. The heat I would suspect is coming from the heat off the back of the radiator, flowing up through the front compartment. Just my guess, but that is where I am starting.
Does anyone have a schematic of the heating and cooling system? I sure could use it.
Thanks a million.
Click to expand...

Have you had a chance to download the free shop manual in the Wiki.
The diagrams and schematics are in there.
Not many of us keep an inventory of pics and schematics when they are readily available on demand for free.
 
Drove the nsx today with the heater valve in the shut position..after 20-30 minutes the radiant heat inside cabin is there. Since I already replaced the seals around the blower, I suspect that the radiator heat is somehow finding its way underneath the lower dash. Now I'm looking towards getting a DF or NsxR radiator hood duct to see if it will solve the issue since it is design to channel the hot air from the radiator towards the nsxr hood opening and away from the front firewall. Anybody has one for sale?
 

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