So two of us at NSXCapades had an unpleasant surprise on the way down - freezing temps in Florida and our heat only working part of the time.
Has anyone else had this problem? Solution? Thanks!
Has anyone else had this problem? Solution? Thanks!
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Heater only works part of the time
- Thread starter boca rat
- Start date
One day it works and the other not ? I would ask BrianK about the climate control unit failing.
I would just check the temp sensor / aspirator fan. If it is shot, disconnected or malfunctioning the car will blow full cold when temp is set under the default value (25 °C, I do not know the value in °F) and full hot when set over the default value. No more continuous regulation. Or something like that. I am not an expert.
I would just check the temp sensor / aspirator fan. If it is shot, disconnected or malfunctioning the car will blow full cold when temp is set under the default value (25 °C, I do not know the value in °F) and full hot when set over the default value. No more continuous regulation. Or something like that. I am not an expert.
Let's start with the basics
. What does your temp gauge read? Did it dip when you lost the heat? Could be as simple as the Thermostat....
HTH,
LarryB
. What does your temp gauge read? Did it dip when you lost the heat? Could be as simple as the Thermostat....HTH,
LarryB
could be as simple as mine. had nabil check mine for the same reason. when changing to heat, instead of the cable opening the valve, the shroud was slipping around the cable. the one under the dash was the culprit. it's the same as the one under the hood near the valve. put some tape around it and put it back in the clamp and it works perfectly.
LarryB, temp gauge and AEM readout are fine, and car has recent coolant flush, thermostat, hoses done. Spoke to Nabil about this and he mentioned the cable stretch, and also to check coolant, but haven't done the latter yet as only remember when I am driving and it hasn't warmed up yet. Will leave a sticky out to do it first thing!
I also checked with the tech who did the big service, and he said he had the climate control cranked to 90 when he did the bleed.
Note this happens several times during a long drive, it's not every other trip. And BrianK fixed this head unit 18 months ago. I guess it could be a new issue though. Actually this was ean exchange unit come to think of it.
I also checked with the tech who did the big service, and he said he had the climate control cranked to 90 when he did the bleed.
Note this happens several times during a long drive, it's not every other trip. And BrianK fixed this head unit 18 months ago. I guess it could be a new issue though. Actually this was ean exchange unit come to think of it.
Coolant level fine - 6" or so in the Dali reservoir, which I am assuming is fine. No real heat at all this morning on the way to the airport, but warming up - it's Florida! I guess heater controls next. What does the aspirator fan actually do?
Can you remember exactly under what condition/rpm it worked and was it consistent under the same condition?
You may have developed new issue and nothing to do with the following points but if it only worked when cruising on the freeway or at high rpm and not at lower speed/rpm range, you may have trapped air inside the heater core.
Quite common phenomenon as bleeding the air from cooling system on our NSX takes long time if vacuum feed was not used.
Even using the vacuum feed, I always double check that there was no air left at the heater core and upper radiator section as these two places are the worst places for getting rid of the air.
Unlike other production cars, the hot coolant enters from the bottom side of the radiator and the same floor coolant pipe is feeding the coolant into the heater core that is located at much higher position.
So, once the air was trapped, not easy to push it down to the floor level and back to the air/coolant separator at the header tank.
Easy to check.
To prevent burning your finger, best to check when the engine is cold or cooled down enough.
The source of the heat is the hot coolant passing through the heater core located just behind the evaporator and the water valve controls the coolant flow rate resulting in mixture of hot/cold air for temperature control.
Pop open the bonnet/hood and find the water valve located at the side of the blower housing.
This photo is from RHD model so on yours, it will be mounted on the opposite side of the blower motor and also the close/open direction is reversed but the function itself is the same.
Turn the IG key into P2 ON position (lots of lights on the dash), no need to start the engine.
Keep the CCU switched Off (no need to run the fan or anything, just press the 'OFF' button to prevent the battery power from draining) and turn the temperature control dial all the way to the coldest setting.
Check the positon of the water valve lever.
It should be all the way to the closed position.
If you look closely on the water valve lever, you can see text 'SHUT' with arrow showing the closed direction.
Now turn the CCU temperature dial all the way to the hottest setting.
The water valve lever should move towards the opposite side.
If it doesn't fully close or open during the above 2 steps, you have problem with air mix control or cable linkage between the water valve and the air mix motor located at the bottom of the heater unit.
By the way, when you move the temperature dial, the same motor that controls the water valve is also operating the shutter door in front of the heater core.
This will adjust the amount of air passing through the heater core fins.
The video shows when you operate the temperature dial from cold to hot.
[Be careful with the next step. It could be very hot if you didn’t wait for the engine to cool down enough!!]
Now touch on the silver L-shaped aluminum pipe with the bleeder plug on it.
(The engine is not running at this stage so no coolant flow through the pipe but this will give you some idea on the temperature change in the next step.)
As mentioned at the beginning, it should be cold or mild if you started this test procedure with cold or cooled down engine.
Now start the engine and keep the CCU temperature dial at the hottest setting.
Don’t touch the TH pedal to keep the rpm at low range.
Just let the system to warm up the engine.
Again, no need to run the CCU fan or anything.
You can keep the CCU switched off.
Let the engine to warm up.
Now touch on the same silver L-shaped pipe with your finger very briefly for like 0.1sec.
Remember, it’s the hot coolant passing through there and it’s very hot once the engine warmed up so please be very careful.
If it’s not hot or just mild, you have air in the system.
With fully warmed up engine, you should not be able to touch the pipe for more than 5sec while the engine is running even at idle rpm.
Stop the engine and let it cool down completely.
If the air was trapped, then don’t try bleeding the air while the engine is still hot.
The entire cooling system is under high pressure so if you open the bleeder, it will erupt.
You’ve been warned.
When the engine is cold, remove the cap from the header tank and open the heater core bleeder on the L-shaped pipe.
You may want checking the upper bleeder at the radiator for any air left but unless you have replacement o-ring or replaced just recently, don't do it.
100% guaranteed to introduce new coolant leakage from there.
Now you should have heater even at low rpm as long as your CCU air mix control (water valve + shutter door control) and the water valve lever cable are operating fine.
Kaz
You may have developed new issue and nothing to do with the following points but if it only worked when cruising on the freeway or at high rpm and not at lower speed/rpm range, you may have trapped air inside the heater core.
Quite common phenomenon as bleeding the air from cooling system on our NSX takes long time if vacuum feed was not used.
Even using the vacuum feed, I always double check that there was no air left at the heater core and upper radiator section as these two places are the worst places for getting rid of the air.
Unlike other production cars, the hot coolant enters from the bottom side of the radiator and the same floor coolant pipe is feeding the coolant into the heater core that is located at much higher position.
So, once the air was trapped, not easy to push it down to the floor level and back to the air/coolant separator at the header tank.
Easy to check.
To prevent burning your finger, best to check when the engine is cold or cooled down enough.
The source of the heat is the hot coolant passing through the heater core located just behind the evaporator and the water valve controls the coolant flow rate resulting in mixture of hot/cold air for temperature control.
Pop open the bonnet/hood and find the water valve located at the side of the blower housing.
This photo is from RHD model so on yours, it will be mounted on the opposite side of the blower motor and also the close/open direction is reversed but the function itself is the same.
Turn the IG key into P2 ON position (lots of lights on the dash), no need to start the engine.
Keep the CCU switched Off (no need to run the fan or anything, just press the 'OFF' button to prevent the battery power from draining) and turn the temperature control dial all the way to the coldest setting.
Check the positon of the water valve lever.
It should be all the way to the closed position.
If you look closely on the water valve lever, you can see text 'SHUT' with arrow showing the closed direction.
Now turn the CCU temperature dial all the way to the hottest setting.
The water valve lever should move towards the opposite side.
If it doesn't fully close or open during the above 2 steps, you have problem with air mix control or cable linkage between the water valve and the air mix motor located at the bottom of the heater unit.
This will adjust the amount of air passing through the heater core fins.
The video shows when you operate the temperature dial from cold to hot.
[Be careful with the next step. It could be very hot if you didn’t wait for the engine to cool down enough!!]
Now touch on the silver L-shaped aluminum pipe with the bleeder plug on it.
(The engine is not running at this stage so no coolant flow through the pipe but this will give you some idea on the temperature change in the next step.)
As mentioned at the beginning, it should be cold or mild if you started this test procedure with cold or cooled down engine.
Now start the engine and keep the CCU temperature dial at the hottest setting.
Don’t touch the TH pedal to keep the rpm at low range.
Just let the system to warm up the engine.
Again, no need to run the CCU fan or anything.
You can keep the CCU switched off.
Let the engine to warm up.
Now touch on the same silver L-shaped pipe with your finger very briefly for like 0.1sec.
Remember, it’s the hot coolant passing through there and it’s very hot once the engine warmed up so please be very careful.
If it’s not hot or just mild, you have air in the system.
With fully warmed up engine, you should not be able to touch the pipe for more than 5sec while the engine is running even at idle rpm.
Stop the engine and let it cool down completely.
If the air was trapped, then don’t try bleeding the air while the engine is still hot.
The entire cooling system is under high pressure so if you open the bleeder, it will erupt.
You’ve been warned.
When the engine is cold, remove the cap from the header tank and open the heater core bleeder on the L-shaped pipe.
You may want checking the upper bleeder at the radiator for any air left but unless you have replacement o-ring or replaced just recently, don't do it.
100% guaranteed to introduce new coolant leakage from there.
Now you should have heater even at low rpm as long as your CCU air mix control (water valve + shutter door control) and the water valve lever cable are operating fine.
Kaz
Last edited:
Kaz, this is awesome.....and I left on a business trip this morning, so don;t get to play Doctor NSX until Friday....aaarrrgghh!!! I'll let you know what comes of this.
Thanks a lot!
Thanks a lot!
Kaz, sorry still haven't gotten back to this as has been unseasonably warm here. Hopefully this weekend.
First of all, Kaz Awesome write up.
You metioned about the pic being right hand drive and the orientation would be opposite. I noticed something else I wanted to mention. On the 1991-94 US models the "bleeder plug" is actually a rubber plug with a clamp, instead of the threaded bleeder in the pic.
See parts pic, items#1 and #18 .
http://www.acuraautomotiveparts.org...ical-exhaust-heater-fuel-cat/water-valve-scat
I noticed Boca's sig states 1992 model year. When I saw your pics, it just came to mind since I just finished a 1992 service...
Regards,
LarryB
.You metioned about the pic being right hand drive and the orientation would be opposite. I noticed something else I wanted to mention. On the 1991-94 US models the "bleeder plug" is actually a rubber plug with a clamp, instead of the threaded bleeder in the pic.
See parts pic, items#1 and #18 .
http://www.acuraautomotiveparts.org...ical-exhaust-heater-fuel-cat/water-valve-scat
I noticed Boca's sig states 1992 model year. When I saw your pics, it just came to mind since I just finished a 1992 service...
Regards,
LarryB
1991 Larry, 1991....last time I looked at least!
First of all, Kaz Awesome write up
I noticed Boca's sig states 1992 model year. When I saw your pics, it just came to mind since I just finished a 1992 service...
Regards,
LarryB
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