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Hello, hope all is well. I have an 1989 6-speed Corvette and while driving there is heat pouring out by my legs when my heater is off. This happens on both the driver and passenger sides. However, when I'm idle the heat does not pour out. The heater itself seems to work fine. I can turn the heater on and off and increase and decrease the heat and temperature levels. It is just that when I turn the heater off, I still feel heat coming out around my legs when I'm driving and it gets worse at highway speeds. More heat comes out the faster I go. As mentioned, when I'm idle the heat does not come out. As you can imagine, this can get quite uncomfortable in the summer with a black on black vette. If any of you have any ideas on what may be causing this problem, your thoughts would be greatly appreciated. Thank you so much.
Mine always seem to have some airflow even with the fans off. At highway speeds I don't even turn it on, I just set the temp to what I want and the airflow does the rest.
In the summer even if I turn it to all the way cool, I still got some airflow and it is warm. The only way I get cool air is to turn the AC on.
I am not sure if you have something wrong like a door not functioning correctly, or if you are just seeing the normal condition. I guess it is a question of how much air flow and how hot is the air coming out.
Sorry not much help, but at least it shows how mine have functioned.
I had the same problem. I took off the 3 bolts on the relay to see the blend door and wedged it to the cold side. Now I have ice cold air. When winter comes, I'll just pull the wedge.
Thank you all for your thoughts, I see I'm not alone. Well, it's hard for me to think that it is normal for hot air to blow out of the floor vents by my feet, and why even more heat comes out at highway speeds -- and when I'm idle the heat does not come out -- and all this happens when the heater is turned off. I have had the car since 1999 and I don't remember having this problem for the first 10 years. I remember taking it to a shop for some repairs on a different issue and when I paid the bill he mentioned some vaguely about missing some parts underneath the dash and I might have heat come out when driving, but it was in the colder months up here in Canada and I didn't notice anything. That's so long ago I can't remember the details. I have been Googling a solution and have read about something called a flap door/blend door/mix door (apparently it is called by various names) and wonder if that my be a possibility, but my heater seems to work fine in that it turns on and off when I push the buttons and I can increase and decrease the fan speed and temperature. It's just this problem of hot air blowing out of the vents by my feet (and more as speed increases), even though the fan is turned off. I have resorted to stuffing towels up the floor vents on the passenger side so my passenger doesn't suffer as much as I do. :-) Note: My air conditioning ran out of freon a long time ago and I never refilled it or updated to new refrigerant. So no air conditioning. Just looking for a solution to stop this hot air. Again, thank you again for your thoughts and how you deal with this issue, appreciate it.
Do you have the electronic climate control? If so set your temp. setting to 60. That will shut off all air crossing the heater core if the unit is still working. Then only engine heat will enter the cabin. That will be warm also. Fix the AC, man.
My 1994 6 speed does the same thing. My AC quit working and all I get is hot air coming out from under the dash. The faster I drive the more hot air blows on my legs and that's not good here in Georgia with no AC to cool things off. I need a new AC system from firewall forward. Was quoted 2K so I'm going to do the work myself for about $800.
I just assumed the air flowing was just the way GM designed the system. I have owned other cars that were designed to always allow fresh air from outside into the car.
I appreciate all of your insights. I set my temp setting to 60 and nothing changed, other than lowering the heater temp to 60, but hot air coming kept pouring out from under the dash -- and that is with the heater turned off. I guess the next option is to look at the blend door as Gatorlaw mentioned. I will have to do some research to know where it is, I don't know where to look for it. I also Googled and read the problem could be that the water control valve or heater control valve is missing, but those were more questions by people and I'm not even sure if a 1989 has them, or if they are missing that this would cause hot air coming out from under the dash with the heater off. Just thinking out loud here and where I'm searching next. Thank you for your helpful words always !
Keep us posted. I have hot air coming out too when the AC is off. In other cars, setting it to 60 or cold does the trick but it doesn't work for me right now probably bc my AC isn't working. Think it just needs a refill
I had sandals on the last time I drove in the heat and at 103 degrees that hot air under the dash almost burned off the hair on my ugly toes!
I appreciate all of your insights. I set my temp setting to 60 and nothing changed, other than lowering the heater temp to 60, but hot air coming kept pouring out from under the dash -- and that is with the heater turned off. I guess the next option is to look at the blend door as Gatorlaw mentioned. I will have to do some research to know where it is, I don't know where to look for it. I also Googled and read the problem could be that the water control valve or heater control valve is missing, but those were more questions by people and I'm not even sure if a 1989 has them, or if they are missing that this would cause hot air coming out from under the dash with the heater off. Just thinking out loud here and where I'm searching next. Thank you for your helpful words always !
Remove the blower motor resistor on top of the heater box. Look down into the opening and you will see the heater door. I forget which way is open/closed, but you should be able to see it move if someone else adjusts the temp from inside the car.
The OP didn't mention (far as I can find) whether it's manual or electronic controls.
Years ago a friend had a car the heater controls didn't turn off the coolant flow completely. From what I remember we got a ball valve with screw in ends, a couple barb connectors similar to what's used to fix a bad garden hose (to fit the feed heater hose) but the other end screwed into the ends of the ball valve (pipe dope or Teflon tape the connections to the valve) along with a couple hose clamps. Cut the hose going into the heater core and put the valve in. Shut the valve and no flow through the heater core. Open it and flow is again restored.
I don't know if it would be a problem if you have electronic heat controls but definitely works with manual ones.
Thank you again for all this vital information my friends, and thank you for posting that photo with instructions on how to check if the blend door opens and closes, Patsgarage. That is so helpful ! Gatorlaw was onto something when he posted his experience with his blend door and said he took off the 3 bolts on the relay to see his blend door, except I had no idea what he meant or where to look until Patsgarage provided the photo with instructions. :-)
I followed Patsgarage's photo and advice and removed the blower motor resistor on top of the heater box and looked down into the opening and saw the heater door. It is not opening or closing when I adjusted the temp from inside the car. Actually, my neighbour was walking the dog and I asked him to adjust the temperature from inside the car as I looked down into the opening. The heater door did not move no matter what buttons were pushed. We raised and lowered to the temperature from 60 up to the hottest temp and the door didn't move -- it just stayed open -- not covering the heater core. I surmise the closed position is covering the heater core. So it looks like it is a faulty blend door (maybe a faulty part or something) or maybe it is not getting the correct electrical information. Again, I'm thinking out loud and will have to research more to plan my next move.
Note: to answer hcbph's question on whether it's manual or electronic controls, I did a Google search and what's in my 89 looks identical to a "C68 Electronic Climate Control HVAC." I simply push the buttons and it automatically changes, so I guess the heater/ac controls are electronic.
One other note: Gatorlaw, I tried to wedge the blend door to the closed position (covering the heater core) to manually stop the hot air blowing out of the floor vents by my feet as I drive, but it would not open without really pulling on it and I didn't want to break it. It opens about an inch, but to open it more I would really have to pull on it. Also I'm not sure it would have even stayed open because like an elastic, it wants to go back. I like the idea though and would do that I could. Well, it looks like we made some progress, but more research is needed to actually fix it. Thank you !
My 89 did the same thing, turns out it was the programmer located under the dash on the drivers side. One of the capacitors had lost contact with the circut board, a little solder and it was good as new. The programmer is a PITA to remove, I wound up taking out the drivers seat for more room. If you do touch the blend door itself be very careful with the plastic clips on either end of the rod, I got everythig fixed and working perfectly, then broke one.
Thank you again for all this vital information my friends, and thank you for posting that photo with instructions on how to check if the blend door opens and closes, Patsgarage. That is so helpful ! Gatorlaw was onto something when he posted his experience with his blend door and said he took off the 3 bolts on the relay to see his blend door, except I had no idea what he meant or where to look until Patsgarage provided the photo with instructions. :-)
I followed Patsgarage's photo and advice and removed the blower motor resistor on top of the heater box and looked down into the opening and saw the heater door. It is not opening or closing when I adjusted the temp from inside the car. Actually, my neighbour was walking the dog and I asked him to adjust the temperature from inside the car as I looked down into the opening. The heater door did not move no matter what buttons were pushed. We raised and lowered to the temperature from 60 up to the hottest temp and the door didn't move -- it just stayed open -- not covering the heater core. I surmise the closed position is covering the heater core. So it looks like it is a faulty blend door (maybe a faulty part or something) or maybe it is not getting the correct electrical information. Again, I'm thinking out loud and will have to research more to plan my next move.
Note: to answer hcbph's question on whether it's manual or electronic controls, I did a Google search and what's in my 89 looks identical to a "C68 Electronic Climate Control HVAC." I simply push the buttons and it automatically changes, so I guess the heater/ac controls are electronic.
One other note: Gatorlaw, I tried to wedge the blend door to the closed position (covering the heater core) to manually stop the hot air blowing out of the floor vents by my feet as I drive, but it would not open without really pulling on it and I didn't want to break it. It opens about an inch, but to open it more I would really have to pull on it. Also I'm not sure it would have even stayed open because like an elastic, it wants to go back. I like the idea though and would do that I could. Well, it looks like we made some progress, but more research is needed to actually fix it. Thank you !
Looks like your blend door is still held onto the blend door motor. If the door does not move freely, you will break the plastic clip and then
you will stuck with more problems.
See the white plastic clip. It attaches to the blend door motor as shown. The other side of that rod is the blend door you see looking down the hole in the engine compartment.
Basically I just wanna say I appreciate how helpful you've been in responding to my post. The pictures have really helped. It looks like we narrowed it down to an issue with the blend door. It's always nice to finally have a lead to solve a mystery problem ! Why won't the blend door move is the question ? Hmmm. Well, it looks like a major aggravation to remove and install, so I guess I'll first see if there is an electrical problem as mentioned by Patsgarage in post number 14, but I'm not an electrician so this doesn't look simple no matter which way I go. I'm glad we got a lead though !!! Hopefully I can post a solution to this, but it will take time. Again.....THANK YOU.
So I just checked this on my '89. When I 1st removed the resister the blend door was all the way to the passenger side\heater core. When I turned the heater up to 90 it moved all the way too the driver side. After turning the adjust to auto, bilvl, or eccn, and temp to 60, the blend door stayed near the 1/4 passenger to 1/2 way position in the middle. Is it fubar? It's electronic on the dash.
I had a quick thought. Since the blend door is the small plastic door that regulates the flow of air through your heater core, if I can't figure out why my blend door is not closing, or some months pass before I can actually figure out the problem, can I use tin foil to cover the heater core as a temporary fix during the hot summer months ? In otherwords, the blend door is not closing and covering the heater core. This allows heat to pour in while I'm driving when the heater is off. So could tin foil act as the blend door and block the hot air blowing out of the floor vents by my feet when my heater is off ? This would only be done during the summer months when I don't need my heater. In the winter time I would remove the tin foil. Theoretically all I would need to do is follow Patsgarage's instructions in post number 14 and remove the blower motor resistor on top of the heater box. Look down into the opening and then place and mould a piece of tin foil to cover the heater core and that would block most of the heat from coming in during summer. OR would that cause any engine/electrical problems ? If that would cause problems, then I wouldn't do it. I'm always interested in your thoughts. Thank you so much.
I am not sure how much luck you would have using tinfoil to block the heat, but it would not hurt anything to try as long as you are sure you could get it out without removing the entire heater box. I would try disconnecting the arm at the actuator by pinching the end with a pair of needle nose pliers (see pic, thanks HAD2HAV2) and usinf the rod to close the door.
06-23-2017, 12:09 PM
Heat while driving, but my heater is off
