Brandon8965

iTrader: (9)

I have run through the car 3 times now and can not figure out why on earth my heater will not go off. No matter what temp I set it blazes the same blisteringly hot air.

Has anyone experienced anything like this before?

njmaxseltd

iTrader: (19)

Auto or manual climate control?

Brandon8965

iTrader: (9)

Auto.. I do apologize

DennisMik

iTrader: (2)

There are 2 items involved. The temperature control part of the heater controls and the air mix door motor.

My car was the motor Pray that yours is the other part.

Brandon8965

iTrader: (9)

so what exactly is it that happened to yours.

i just went out and took a look at it just to see.. that is in a god awful location!

DennisMik

iTrader: (2)

The motor died and I had to replace it. God awful job. I followed the troubleshooting guide in the FSM to figure out if the dash control or the motor was the problem. And the troubleshooting procedure was't exactly crystal clear either. Once I felt positive that it was the motor, I tried to find out exactly how you replace that motor. But I never did find one.

The motor is held on by 3 Phillips head screws. It looks possible to get the motor out if you remove the ECU. People have taken the ECU out, but I'll be damned if I could get mine out.

So I decided to take the dash out and remove that whitish box that the motor is mounted on. I got the dash out and took all the bolts out for the white box but then found out that to take that box out, I needed to take the hoses off the heater core, which happens to be mounted in that white box and also drain the a/c because the evaporator core has to be removed to get the white box out. I was ready to toss in a gallon of gas and a match.

While I was crying in my beer, I was looking at my mess from every angle I could. I finally realized that if I took out the air ducts that run town the floor hump to the back seat, I could get at the motor mounting tabs with a hack saw blade and cut them off. Once I had cut the motor out, I used a small (4"?) pair of vice grips to get the Phillips head screws out. To mount the new motor, I used hex head screws because there is not enough room for the vice grips.

And don't be thinking "Why didn't that a-hole use an off set screwdriver?" The answer is - there's not enough room.

It probably took me something like 10 hours, but in my defense I took a lot of photos and created a how-to thread for removing the dash. That and too much time crying "why me?" It can probably be done in 4 to 6 hours depending on how determined you are. Once you know where the screws are, you can do the dash by yourself in an hour or less.

Here's a link to that thread. Further down in the thread I did post a photo of the air mix door motor.

http://forums.maxima.org/4th-generat...dashboard.html

njmaxseltd

iTrader: (19)

You realize with auto climate control, even when it's off air will Coe through the system tempered to what your set to. Example, you had heat on 85 degrees then turn it off. You'll still get hot air out the lower level until the car hit 85 degrees. Turn the temp down to the min and you'll get only outside non-tempered air through the system.

Brandon8965

iTrader: (9)

thanks for that.. i will take a further look at it from that angle..

with your motor dead the heat never went off at all? that just sounds weird

yes i do realize that.. that's why i said no matter what temp i set

DennisMik

iTrader: (2)

You have to understand how the heat system works. In the maxima (probably all nissans) the engine coolant flows through the heater core all the time - there is no water turn off valve.

So to regulate the temperature in the passenger cabin, they direct the air either through the heater core or around the heater core or a mixture of both for middle temperatures.

The directing of the air is done with a flap inside the air ducts called the Air Mix Door. And the Air Mix Door Motor is used to move that door. If the motor or the control unit fails while the door is channeling all the air through the heater core - you have heat all the time.

Brandon8965

iTrader: (9)

that makes perfect sense.. i will have to look at that in the morning.. hopefully if that is the case i will be able to remove it by the ecu and not take apart the entire dash

DennisMik

iTrader: (2)

Before you buy any parts, get down in the passenger side footwell and pull off the plastic console cover so you can see the ECU. Then look at the Air Mix Door Motor while you change the temperature setting. Don't forget to turn the ignition switch on when you do this. If you see the arm on the motor moving, you have a broken door inside the duct.

Brandon8965

iTrader: (9)

^ will do.. thanks for the help

i'll post with updates

Brandon8965

iTrader: (9)

so i looked and saw what appeared to be a door moving but it looked to me like it was just routing the air from the dash vents to the floor so maybe i was looking in the wrong area.

This is killing me!

DennisMik

iTrader: (2)

You cannot see the air mix door itself, it is completely within that big white box.

Were you in the passenger side foot well looking at the motor that sits just over the ECU? The air mix door and its motor have nothing to do with what openings the air blows out of. Changing the temperature setting will not cause any changes to vent settings. Vent settings are changed by the Mode Door Motor that is visible from the driver's side foot well.

Brandon8965

iTrader: (9)

ah! so how exactly did you determine the motor dead

it seems every time i have time off to do this it is raining!

DennisMik

iTrader: (2)

I followed the diagnostics in the service manual and and found that the control panel in the dash was sending voltage to the motor and the motor did not move. I don't remember if I tried to jumper power directly to the motor or not. But I checked and found that the wires were good and that the heater control was sending voltage, so I probably didn't jumper the motor directly.

dwapenyi

iTrader: (3)

I am glad to learn this. This will help the heater core last longer.

Thanks