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Discussion Starter #1
Ok so heres the deal. Cold air comes out of my vents most all of the time. The only time that it comes out warm is when I put the heater on vent. However, if I put the blowers on the defrost or the floor or a combination of those, freezing cold air comes out of my dash. If I put the blowers on bi-level (feet and dash) then warm/hot air will come out of the dash. I know my relay switch is out but that has nothing to do with it. The vents will blow out cold air when I am sitting still at a light but when I am moving then the air volume is increased slightly.
Please help me out people, its really cold here in Michigan!
 

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is this with the HVAC ctrl on or off (is it on OFF or one of the numbers?) cuz mine blows out air all the time even when its off.....so in the summer i just keep the temp control at the coldest side, and in the winter i keep it on the hottest side, so that way itll blow warm air when i want it and cold air when i want it.
 

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the fact that u get warm air on one setting is puzzleing but id still have to say its the thermostat considering u said u never get hot air at all, if u cant remember last time it was changed, take 5 bucks and 10 minutes and give that a shot
 

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I am racking my brain. First, I was thinking something is wrong with the controls to the doors that switch the heat from defrost to floor to vent. To get the most heat, move the one lever to recirculate. If that door is closing properly, it should block the cold air from coming in. Heat should increase. I have dropped the fan motor several times when my the recirculate door stuck closed. Then there was a pesky squirrel who stuffed grass and nut shells in my evaporator (that is another story). Another thought is you have an air bubble in your antifreeze system, that could be reducing heat. It would be good to make sure you have plenty of antifreeze and the air was properly bleed that last time it was serviced. I think Lew posted a sticky on how to do that. Is your engine temperature gauge going 1/4 or 1/3 of the way or so when the engine is warm? If not, the thermostat may be stuck open. I am just giving ideas. Also, a plugged heater core would be a possibility, but that does not explain why you get some heat on the vent setting. My brain is overheating, so I will stop for now. :)
 

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naw i think that's a common problem...i have the exact same issue. outside air is always blowing through the dash vents regardless of the control settings.

i can have them set to "off" and air will still be blowing from the dash vents. the only time they stop blowing outside air is when i set the controls too the dash vents.

i dont know if that helps any.
 

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Ok it cant be a thermostat, cause he would be getting no heat period, or his car woudl be over heating. He is saying that he is getting heat on some positions of the selector nob. So it could be something in your air ducts.My guess
-Ben
 

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Discussion Starter #8
Tavel said:
outside air is always blowing through the dash vents regardless of the control settings.

i can have them set to "off" and air will still be blowing from the dash vents. the only time they stop blowing outside air is when i set the controls too the dash vents.

i dont know if that helps any.
This is the exact problem I have....just put into simpler terms. It does seem to be coming from the ducts or something, not electrical or anything. I have never even seen the duct work on my car, does anyone know how to get to it?
 

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live4snow said:
It does seem to be coming from the ducts or something, not electrical or anything. I have never even seen the duct work on my car, does anyone know how to get to it?
Not really. I was looking up in Alldata but they basically showed how to take apart the dash to replace the heater core. Now Haynes has some pictures of adjusting the temperature control levers. Maybe a cable slipped/lost adjustment, or broke. There is a clamp that needs to be secured to keep the proper position.

Haynes has a picture of the Temperature Control Adjustment. Looks like you may be able to see it if you look under the dash on the passenger side. On 91-94 models it says to set the lever to the maximum HOT and pull the door back, then secure the clamp.

Maybe that clamp came loose. I have never looked at the B14 FSM, that may have some detailed information. If you have access to a Haynes manual, it may be helpful
.
 

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When i got my 94 in Jan. last year i had the NO HEAT problem so i traced it down the thermostat. Replaced it and had SOME warm air, finally just kept keeping an eye on things to see when it got warm etc. i noticed that as you were moving it would blow much warmer air but at a light just cool air! This winter i decided to put a piece of cardboard in front of the rad (something my dad told from his day) and believe it or not i now have heat! Of course come spring and the warmer weather i'll take it out but for now no probs and i have heat, the bottom line is i think these cars heaters are cold to begin with you just have to live with ti!
 

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Discussion Starter #11
new94 said:
When i got my 94 in Jan. last year i had the NO HEAT problem so i traced it down the thermostat. Replaced it and had SOME warm air, finally just kept keeping an eye on things to see when it got warm etc. i noticed that as you were moving it would blow much warmer air but at a light just cool air! This winter i decided to put a piece of cardboard in front of the rad (something my dad told from his day) and believe it or not i now have heat! Of course come spring and the warmer weather i'll take it out but for now no probs and i have heat, the bottom line is i think these cars heaters are cold to begin with you just have to live with ti!
No I think you misunderstood. My car heater works fine, its just when the setting isnt on vent, cold air blows out of the vents.
 

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Discussion Starter #12
Catman said:
Not really. I was looking up in Alldata but they basically showed how to take apart the dash to replace the heater core. Now Haynes has some pictures of adjusting the temperature control levers. Maybe a cable slipped/lost adjustment, or broke. There is a clamp that needs to be secured to keep the proper position.

Haynes has a picture of the Temperature Control Adjustment. Looks like you may be able to see it if you look under the dash on the passenger side. On 91-94 models it says to set the lever to the maximum HOT and pull the door back, then secure the clamp.

Maybe that clamp came loose. I have never looked at the B14 FSM, that may have some detailed information. If you have access to a Haynes manual, it may be helpful
.
Come to think about it, the center two vents on the dash are connected to one switch to either let air flow through or block it off. I remember when wiring up my stereo, the cable looked like it was in bad shape so I cleaned it up a bit. Now the lever that is supposed to close off the vents barely moves. I have no clue to where the cable goes so I dont really want to just tear my dash apart aimlessly. And since I don't have access to a Haynes Manual, this is the best help that I can get right here, online. But that doesnt explain why the side vents blow cold also. So the only thing that I can think of is that the main switch that changes it to vent or not is screwed up somehow. But thats weird because I am almost certain that I can hear the vent closing off. Ahhhh!!! I think I'm going crazy.
And I dont think that it is the temperature control adjustment, I think its with the vents but Ill check it out tomorrow.
 

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You are probably right. I described the wrong one. The Temperature Control Adjustment illustration was specific to the 91-94 Sentra. Haynes has a picture for an air control cable adjustment. It says to set the control levers to the defrost position, then push the link and lever back toward the clamp and secure the clamp. It shows pushing the link and lever down and toward the right at about a 45 degree angle before securing the clamp. Does not specify the year with this procedure. Unfortunately, you may have to remove some things to get to the cable. I think you will at the minimum remove the center cluster trim panel. Then Haynes says there are some screws that hold the heater control assembly in place. Then it says to pull and tilt the unit out of the dash. Once you do that you may find the cable or door binding. My bleed door for recirculate was stuck shut when I got it. The dealership wanted about $400 to replace the assembly. I dropped the blower motor, put some Vaseline on the sticking edge of the sticking door, and have not had a problem since. So, things may be binding, or organic matter may be obstructing things. Like I said, I had a squirrel that put all kinds of junk through the evaporator that started blowing through the vents. Things should move freely. Something seems to be binding. I have a feeling the door itself may be binding, and the cable is trying to move it as best as it can. Anyway, that is all I have for now. Good luck.

The idea of cardboard is one I am using this winter. It was so cold one day coming up from my parents that the engine cooled off (no heat). I believe it is just the way it is designed. I put two square lids from some cat litter pails in front of the condenser. It blocked the air enough to so the engine would not cool down from the flow of cold air through the radiator. Easy to install and remove.

It just occured to me, that if the Temperature Control Adjustment is working poperly when you put it on "Hot" it should not matter if it is going the defrost, side vents, floor, or front vents. It should be hot when set to hot no matter which vent it is going through.
 

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Discussion Starter #14
Catman said:
I have a feeling the door itself may be binding, and the cable is trying to move it as best as it can. Anyway, that is all I have for now. Good luck.

It just occured to me, that if the Temperature Control Adjustment is working poperly when you put it on "Hot" it should not matter if it is going the defrost, side vents, floor, or front vents. It should be hot when set to hot no matter which vent it is going through.
I also think it is the door that is sticking or something is not hooked up right. However sice I have many tests and projects due this next week, I am afraid that this is going to have to wait until either next weekend or until I skip again. Haha.

And my heater does blow hot. Its just that cold air comes out of the vents when the heater is not on vent.
 

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Take care of the tests and projects. You wouldn't want to skip class over this. :) This is probably one of those things you want to check out when you are not in a hurry or distracted. You want to get everything back together without too many broken or missing parts (that is what happens to me). :thumbup:
 

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Question for Catman

Hi Catman...let me rack your brain again....I had a problem with my blower..only worked on speed 4. So I replaced the blower motor resistor. That solved the blower problem...now it works on all speeds....My new problem is that now it only blows cold air...I set it to hot and just cold blows out, and I start smelling something burning...Got any ideas??


Catman said:
I am racking my brain. First, I was thinking something is wrong with the controls to the doors that switch the heat from defrost to floor to vent. To get the most heat, move the one lever to recirculate. If that door is closing properly, it should block the cold air from coming in. Heat should increase. I have dropped the fan motor several times when my the recirculate door stuck closed. Then there was a pesky squirrel who stuffed grass and nut shells in my evaporator (that is another story). Another thought is you have an air bubble in your antifreeze system, that could be reducing heat. It would be good to make sure you have plenty of antifreeze and the air was properly bleed that last time it was serviced. I think Lew posted a sticky on how to do that. Is your engine temperature gauge going 1/4 or 1/3 of the way or so when the engine is warm? If not, the thermostat may be stuck open. I am just giving ideas. Also, a plugged heater core would be a possibility, but that does not explain why you get some heat on the vent setting. My brain is overheating, so I will stop for now. :)
 

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Actually, my brain is still overheating. If you could blow that cold air over my brain, you would get some heat. :) The problem is the references I have, Alldata and Haynes are limited in this regard. Maybe looking at the B14 FSM would give some ideas on troubleshooting/repair in this regard. Good luck!
 
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