Heater blows cool air except when car is moving...what is wrong?

Meeyatch1

Meeyatch1

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As the title states, I am having an issue with my car. It is about 8 degrees outside today, and it took about 10 minutes of driving before my car warmed up, and once it did the heater only seemed to blow hot air when the car was moving. If I was stopped at a stoplight the air was pretty cool, but once moving, the air was warm again. The climate control was rebuilt a few months ago so I do not think that it is. This happened while the climate control was set to 90 degrees in 'Full Auto' mode. It still did it when I turned off the A/C and stayed in simple 'Auto' mode, but still at 90 degrees. Any ideas what is going on? I am freezing over here! :frown:

(*By the way, the model year for my car is 1994 if that makes a difference.)
 
Sounds like your thermostat valve has stuck open meaning your car's coolant is flowing too much and taking longer for the car to warm up.Lets wait to see what the gurus say.
 
I hear ya. It's zero here in Chicago and I only get warm air when moving. A long stop light and it feels like the air is on. My temp guage reads normal, coolant is full. 20 degrees out and I dont have any issue, below that and I put a hat on at each stop light. :confused:
 
I had similar symptoms when my climate control board coughed up a hair ball. After coolant level I would think some of your capacitors have leaked onto the circuit board like so many before. Do a search - I think BrianK was fixing them once upon a time. It is a double sided board but if you are handy and have a soldering gun and patience you can repair the circuits and replace the capacitors. Good luck!
 
Greetings

I drove mine into work all last week with the top off on the way in and the way home -- sorry, I couldn't resist. My guess would be either a stuck thermostat, kinked hose, or low coolant. The flow to the heater core would be significantly less at an idle. How long does it take for the air to get cold -- almost immediately, 15 seconds, Etc? Here are the items I would look at/for:

1. Low coolant.
2. A kinked hose under the body.
3. A thermostat stuck open.

You could cover part of the radiator with some cardboard for an experiment. Drive the car until it is good and warm. This would keep the water in the radiator and engine warmer, so the delay in the heater cooling down would possibly show you that the thermostat is open.

Martin
 
Briank said:
First thing to do is bleed out any air in the heater core. Next check to see the water valve is opening all the way.
Click to expand...

How hard is it to do both of these functions? I would like to get this fixed so that I do not freeze to death. LOL! :tongue:
 
First off, you have to realize that the water for the heater core has to travel from the engine, under the car in un-insulated thin wall tube, to the heater core. Also, there is no heat generated in the forward compartment like in normal front engine cars to radiate into the cabin. Our mid-engine cars are not going to have the greatest heaters in the winter. When the engine is at idle the water circulation is reduced also. So heat disipation forward of the engine increases and don't forget the heater core is pulling off all that it can get.

I agree with what has already been mentened about possibly the thermostat, but if the engine is warming up to normal temp at normal rate, even when it is cold outside, then this would not be my first guess. If the engine warms up to almost normal level at a slow rate, in the winter, then the thermostat would be the winner. Too much water circulating and too much cooling to allow the engine/heater core to warm. Now the heater core water control valve is not very likely because you say that you are getting hot air when the engine is at other than idle, but check it anyway, it's easy.
Are you running the heater intake air on FRESH or RECIRC? RECIRC helps for the initial warm up, but you should switch to FRESH after that to reduce the fogging on the inside of the windows from the increase of humidity in the car. That is why you see cars in the winter with the inside all fogged up, they are using the RECIRC instead of FRESH. People don't understand that the outside FRESH air is LESS humid than the inside air when using RECIRC after a few minutes. Human resperation produces abundant humidity, especially when there are three or four people in a car. Sorry, got off on a rabbit trail.

Now air in the system, if the system was properly bleed before and nothing has been done to the coolant system and there are no leaks and you haven't been having to add fluid, is a long shot.

The EASIEST thing you can do, is verfy the coolant level is at the proper level and there are no visible leaks. Get a piece of cardboard the size of the radiator, doesn't have to be exact. Remove the two bolts, 12mm if I remember, that holt the top of the radiator. Don't let the hood drop on your head! Gently push the radiator back and install the cardboard. Drive the car. See what happens. This will confirm or deny the thermostat being stuck open.
When I was bringing my car home in the spring of 05 I was in Nebraska/Wyoming in a snow storm, no heat, at 4 o'clock in the morning. I had one of those fold up foil sunshades in the trunk that the previous owner said "Just Keep It", (I almost threw it out). I stopped under an exit light got out and installed it in front of the radiator, WALAA, 2 minutes later I had heat. The engint temp had been slow to come up to temp, the previous two days in Texas 60-70 degree temps, and would increase slightly with the increase in outside temp as it got later in the day.
Just my .02 cents worth,(or was that $2 worth)
Brad
 
The symptoms is the opposit to a thermostate.

When its a thermostate failure, the coolant does stay cold and either it takes the car a long time to warm up, or the car will not warm up at all.

Also the car will warm up when your driving city but will cool down when your on the high way.

Think about this. If the thermostate is consitantly open, if MORE air flows through the radiator, the coolant would stay cooler.

So, if the thermostate was the issue here, the car would have the opposite effect where when driving on the high way, the coolant is cooler and warms up when the car is stopped or city driving.

When coolant is low, the coolant will flow to the lowest point first which is the radiator. The heater core is located high in the cockpit and thus when the car is sitting still and the water pump is turning slowly, not enough preasure is in the system to boost the coolant up to the heater core. Also when the engine is producing low heat such as an idle at stop, the coolant expands less to fill all the voids.

The heater core by itself is too small to cool down an engine or prevent it from warming up. There are other things at fault with the coolant system. When the car over heats, you can use the heater core as an additional way to delay the boil over but having it on recirc or fresh air will not much difference..... but with that said, 8'F is pretty cold :D

When the car starts up and the water pump start going usually the water reaches the heater core.

Here is what you can do with the nsx. fill the coolant bottle with 50/50 honda mix coolant till the full line on the coolant tank.

Dont worry about bleeding it since your not doing a complete flush, the air will work its way out through expansion and contraction if its not a lot of air.

if you over fill the tank its no biggy, the extra coolant will get vented out through the heat cycles and eveturally your coolant will equalize.

Happy motoring

Rob:smile:
 
Sounds to me like the water valve is not opening all the way, and you need max circulation in the system to keep the heater core water warm. The water valve is located just to the left of the brake master reservoir(LOOKING FROM THE FRONT BUMBER BACK, not from the drivers seat)

Look Here:

http://www.acuraautomotiveparts.org...omp=List All&vinnoT=&trim=&trans=&view=normal

Item #5 is the water valve. When you look into the front bay, the lever should be all the way towards the front of the car. You can disconnect the actuation cable and try to move the valve through its range of movement. If the valve goes further forward when disconnected, first thing I would do is leave it disconnected and have the water valve all the way open. Go for a test drive and see what happens. If that cures it, adjust the cable. It is an issue I have seen before, that when a hose change is done, the cable may get randomly mis-adjusted.

HTH,
LarryB
 
Okay, among other things I am updating, this issue made the decision for me that I am just going to flush all of the coolant, and replace the thermostat. The OEM Honda thermostat is only a $40 part, and Honda coolant is not much money, so I am just going to replace it all just in case. I plan to have this car for a long time, so no reason to be a cheap skate. If I wanted to be cheap, I would have bought a used domestic. ;) Now...the question becomes, how do I do this? Can I flush the entire system at home by myself? Is it hard to change the thermostat?
 
Just burp the system just behind the spare tire. Engine running, crack open the little bolt head that has the little hole in the middle. Be careful it may be hot.

Larry knows this procedure


HTH
 
woodwork said:
Just burp the system just behind the spare tire. Engine running, crack open the little bolt head that has the little hole in the middle. Be careful it may be hot.

Larry knows this procedure


HTH
Click to expand...

Thank you! I appreciate it. Is there any need to drain the entire system and try to force flush coolant through there to clean out any residue or contaminants that may have built up over the years, or is that not really an issue?
 

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