Hot air coming into the cabin

[jagtiger]

Thats definitely one of the causes but both jagtiger and I were getting warm air from the air vents. I was not getting any leaks from the foam seal. The hot air seems to likely be from a failed coolant valve allowing some hot coolant into the heating elements and thus heating the air.

Im ordering a new valve to see if that fixes it.


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Hey lithiumus,

I did replaced the seals and the valve but the hot air issue remains. You are probably right that the valve indeed detoriates over time thus allowing some coolants into the coils. I did replaced my valve with a used one off from ebay. Anyways please let me know when you install your new valve and it solve the issue. Thanks Lith

 

[JRZ]

Don't have anything positive to add but, forgot to mention that I have insulated the cabin fresh air inlet on the windshield wipers where there's only air going into the car from the very far edge of the hood. I have the duct hood and wanted to eliminate any chance of the hot air getting back into the car. Sucks that we can only have the windows down on a brisky day .

 

[lithiumus]

Hey lithiumus,

I did replaced the seals and the valve but the hot air issue remains. You are probably right that the valve indeed detoriates over time thus allowing some coolants into the coils. I did replaced my valve with a used one off from ebay. Anyways please let me know when you install your new valve and it solve the issue. Thanks Lith

Ive ordered a brand new part and will inspect and test it and compare to the one im pulling out of the car.


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[jagtiger]

Ive ordered a brand new part and will inspect and test it and compare to the one im pulling out of the car.




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Hey lithiumus any news?

 

[lithiumus]

Trying to order the valve. Its on backorder from honda with no eta so still waiting...


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[Valhalla]

Trying to order the valve. Its on backorder from honda with no eta so still waiting...


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I ordered this off Amazon just last month. Part Number is 79700-SLO-A01 and received it just a couple of days later. It was packed in a genuine Honda bag and was just over $103. Here is a link;

https://www.amazon.com/Acura-79700-...automotive&vehicleId=1&vehicleType=automotive

Good luck.

 

[lithiumus]

I ordered this off Amazon just last month. Part Number is 79700-SLO-A01 and received it just a couple of days later. It was packed in a genuine Honda bag and was just over $103. Here is a link;

https://www.amazon.com/Acura-79700-...automotive&vehicleId=1&vehicleType=automotive

Good luck.

Thanks Valhalla,

Its currently “temporarily out of stock” at Amazon. Ill wait a little longer and see...




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[jagtiger]

I ordered this off Amazon just last month. Part Number is 79700-SLO-A01 and received it just a couple of days later. It was packed in a genuine Honda bag and was just over $103. Here is a link;

https://www.amazon.com/Acura-79700-...automotive&vehicleId=1&vehicleType=automotive

Good luck.

Hey JC,

Did you have the same cabin heat problem? If so did the new valve help?

Thanks
Henry

 

[lithiumus]

Hey JC,

Did you have the same cabin heat problem? If so did the new valve help?

Thanks
Henry

JC just sent me his unused valve. He indicated that he disconnected the pull wire from the valve and tied the valve shut to keep it permanently closed.

I wanted to have a new valve to confirm if its my valve or the pull cable but im pretty certain my pull cable is closing my valve fully.


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[Valhalla]

He indicated that he disconnected the pull wire from the valve and tied the valve shut to keep it permanently closed.

I wouldn't say permanently. I have zip-tied it closed for now. I have adjusted the cable as far back as it would go but it still wasn't far enough back for me to feel comfortable that the valve was completely closed. As I use the A/C most of the year, I'm OK with this workaround for now. Maybe later this fall, up in the bay area for NSXPO, I may feel the need for some heat. If so, I'll just snip the zip-tie and place the cable back on the pin. The cable does move and the valve does open and close. I'm just not confident that the valve closes tight. I can zip-tie it closed again after leaving NoCal. I always carry a couple of zip-ties in the car, who doesn't?

 

[lithiumus]

Ok finally going to install the valve this week. But I also purchased bypass caps just in case this does not work. I tested the new valve and it closes fully but the inside stopper looks to be plastic so it's possible it deteriorated. Will check the old valve shortly and report back.

 

[lithiumus]

I removed and installed the new valve. The old valve seems to work when it's closed. There is definitely build up of some sort inside and around the outlets on the inside. As far as I can tell, the old valve should have been working properly and I definitely adjusted the cable. I did see markings with a blue sharpie supposedly marking the position of the arm when open and closed. The marking where it was supposed to be closed was actually not fully closed. It's possible that the cable does not retract enough to fully close the valve so I'll have to check that next. The car is up on my lift with the battery out so as soon as I re-install the battery, I'll test the cable movement at the coldest / full close position and compare to the removed valve.

 

[lithiumus]

Ok. I did some testing and maybe it's just OEM angle of the valve, etc but I'm suspecting that it just does not fully close. It seems to "almost" fully close. If you push it all the way back and lock it. I decided to unlatch it, set to full cold and push it a bit further and lock it in place. Had to struggle a bit to get the loop on but it seemed to be tight.

I did test drives and there is still "warm" air coming in but it's just slightly warm and definitely not hot like before.

So I can confirm that the valves were NOT the issue and it's the cable locking position, but I also do not believe that you can fully close it 100% and it still let's in enough coolant that you will feel warm air. At least it's not hot air.

I've got bypass coolant caps but that might be taking it a bit far. Valhalla's Zip tie may be the way to go for the hot summer months, and leaving it in for spring and fall for warm air is probably fine.

 

[Valhalla]

Ok. I've got bypass coolant caps but that might be taking it a bit far. Valhalla's Zip tie may be the way to go for the hot summer months, and leaving it in for spring and fall for warm air is probably fine.

This is what I am still doing and it works great. No issues all summer long down here in the Valley of the Sun. But I'll be snipping off the zip tie next month when I know I won't be using the AC. Thanks for telling us of your progress.

 

[jagtiger]

Hi JC and Lith,

Would you mind thaking a picture how exactly you installed the zip tie?

Thanks in advance.

 

[YellowScorpion]

Bumping a old threat but. Currently having an issue where my heat went out while driving and started blowing cold air into the cabin. I went through and found my cable to not actuate between the hot and cold setting on the ccu. While the cable is in the "retracted" position, it clicks and is very hard to get out of that position. Once the cable Is freed from the locking "click" retracted position, it moves freely but still with no assistance from the motor that is meant to actuate the cable. Any advice on what it could possibly be? This seems like it is an issue that'll need the dash taken out to solve but I would rather hear what the experts have to say first.


Edit: updated details about current issue

 

[Honcho]

I just did the job of attaching the cable to the motor. Sadly, I think you might need a new air mix motor. It sits on the bottom of the HVAC unit (3 screws) and controls the cable. Part # 79160-SL0-A01 You will need to take the dash out.

 

[YellowScorpion]

I was looking all night for what the motor/actuator was called, your comment was a big help! After looking in the Service manual 22-9 and 22-27 both seem to have the air mix motor possibly accessible from the passenger footwell. how realistic would it be that i could do this job without taking out the whole dash?

I just did the job of attaching the cable to the motor. Sadly, I think you might need a new air mix motor. It sits on the bottom of the HVAC unit (3 screws) and controls the cable. Part # 79160-SL0-A01 You will need to take the dash out.

 

[NSX_n00b]

I was looking all night for what the motor/actuator was called, your comment was a big help! After looking in the Service manual 22-9 and 22-27 both seem to have the air mix motor possibly accessible from the passenger footwell. how realistic would it be that i could do this job without taking out the whole dash?

What you're seeing on those pages is an X-Ray vision of what's back there. The dash has to come out in order to replace that motor.

Now the worse news...and [MENTION=18194]Honcho[/MENTION] can correct me if I'm wrong...but the whole EVAP needs to come out as well. The motor is mounted to the bottom of the unit (if it's the one I think it is) and the only way to access the 3 screws holding it onto the evap is from underneath. Well the SRS controller is right there and in the way so you need to pull the EVAP out so you can remove the motor and put the replacement motor on.

 

[YellowScorpion]

So after just taking a peek in the passenger footwell. with the underpanel removed (missing) i can see a small set of plastic gears that move along with the turning of the temperature knob, i guess i really will need to remove the dash :/

Good News guys! i just did a Manual conversion to my Climate Control! Selling manual conversion kits for $499.99, a real steal compared to that pesky Automatic climate control adjustments!

Edit: Ive removed the glove box and the air tube that leads to the door vents. and from what i can see, most of the EVAP unit is accessible from this side. Does anyone have a image of where this motor is on the EVAP unit? Im hoping the cable got unhooked from the motor and i can easily reattach it?

 

[NSX_n00b]

As you can kinda see in the second picture, the cable is on the left hand side of the evap and leads to the motor under the evap unit, but here is two pictures that hopefully help:

http://www.nsxprime.com/photopost/nsx-prime-member-galleries/p4064-evap-2.html

http://www.nsxprime.com/photopost/nsx-prime-member-galleries/p4063-evap-1.html

 

[789]

I doubt you will have enough room to remove the motor under the evap. unit without taking out the dash OR even you may have to remove the evap to remove the motor. Unfortunately, I don't have a clear photo to show the space below the evap., but that's really minimal. You may see from the first 2 photos I attached below to show you all the carpet removed prior I removed the dash and the next photo to have the dash removed and the last photo shows there's nearly no room between the evap. and the central tunnel (see arrow marked in RED). Hope it may help you to visual more about the space. Good Luck!

 

[Kaz-kzukNA1]

It can be removed without taking the whole heater unit or the entire dashboard off the car.

However, only done it on the RHD model and thus, if you have LHD, the orientation, position, etc would be different/reversed from the above photo so please be careful.


In post #70 above, you mentioned that you saw some movements at the motor.

If that is the case, before trying to remove the motor, I recommend using the mirror, endscope, etc to check the movement of the motor lever/cam where the water valve cable is attached.

The air mix motor is attached right at the bottom of the heater unit.

Again, this photo is from the RHD model.

Please note that this motor not only controls the water valve under the bonnet/hood through the cable but also adjusts the air mix door/damper in front of the heater core by rotating the spiral shaft.

This video shows the door movement starting from cold (closed) to hot (open).

It controls the amount of air flow passing through the heater core behind.

At the same time, the water valve cable controls the amount of hot coolant passing through the heater core.

With these two controls plus the temperature of the air flow from the blower fan together with the feedback from the cabin air temperature sensor, the cabin temperature is controlled.

The centre shaft is inserted into the [ + ] slit of the air mix motor and the water valve cable moves in parallel.

If removing the motor body, you want to keep/set the relationship between the water valve cable and the air mix door properly.




If you can confirm that the motor lever is moving, then I would first check the water valve cable holder.

From time to time, I saw the cable/sleeve being unlocked or the bracket itself being bent due to some work done inside the cabin.

Or, simply someone pulled the other end at the water valve too much.

If someone worked inside the cabin in the past, something could be preventing the smooth operation of the water valve cable.

Possibility of damaged/bent cable as well.


At the air mix motor, the edge of the cable sleeve should sit right at the round notch of the cable holder.


Kaz

 

[jagtiger]

Kaz,

This is some great information - very detailed with photos. Thank you for sharing.

Would know if the cabin hot air issue that some of us are having is associated to maybe a failed component or just need a proper adjustment in the a/c air mix unit?

 

[Honcho]

Kaz,

This is some great information - very detailed with photos. Thank you for sharing.

Would know if the cabin hot air issue that some of us are having is associated to maybe a failed component or just need a proper adjustment in the a/c air mix unit?

Having gone through all of these components recently, I would address any leaking hot air issues in this order:

1. Check cable adjustment at the water valve in the front bay. It does close all the way if properly adjusted and no coolant flow should reach the heater core in this stage. The cable can slip over time and end up not fully closing the valve;
2. As Kaz mentioned, use a mirror and check the movement of the air mix motor and cable position as you slowly increase temperature on the CCU. Much more rare than the above, but if the cable has somehow slipped out of position, it will cause the exact same symptoms as above. Similarly if the motor fails or is slipping/stuck, you'll see it.
3. Finally, and this may require removing the HVAC unit, you should check the air mix doors to make sure they are fully closed and sealed at the "cold" position. If they are jammed or otherwise out of position, or if the foam has deteriorated, warm air may be "leaking" past the seam.

The early cars are reaching the end of service life on many components and the HVAC unit is one of them. I suspect a lot of them are exhibiting this issue due to the above factors, which are inevitable considering they are 30 years old. Thankfully, members like Kaz and [MENTION=31168]nsxspdfreak[/MENTION] offer services that clean, check and re-foam the unit. Many owners in Japan simply buy a brand new, complete unit and swap it in. Obviously much more expensive than a re-build, but you get the advantage of all new motors and thermo-probes too. Good for another 20-30 years.