SO here's my dilemma:

We've recently taken a trip to Arizona, the entire trip was extremely hot. Keep in mind the outside temperature was around 60-70F Degrees the entire time and it was on a highway at 80 miles an hour pretty much the whole way. The trip was 10 hours long.

Before the trip my dad had problems with the heater staying on even when he had the AC off. On the way to Utah to pick us up he had some success by turning the AC from auto to manual and switching it down to the lowest temperature possible, and then back to the highest, and then back to low again to receive good cool air.

But on the way up here no matter what we did, even when turning the A/C off completely, the car would blow really hot air on our feet.

My dad is an helicopter mechanic, so he knows his way around metal, we've come to a conclusion after staring at a manual for hours, we just need to know if it's the right one. We think something called the "solenoid valve" is the problem. Maybe it's not getting power, or whatever, but that's what we think. We need more opinions on it though.

Thank you for your time It'd be helpful if we could get a quick-fix by tomorrow morning, as that's when we have to make the trip back home and we would prefer to do it comfortably.

 

There is no solenoid involved for your problem. At this point in time there is no "quick fix" except to set the controls to floor and stuff rags into the air outlets.

Nissan adjusts the passenger cabin air temperature by directing the air flow through the heater core or around the heater core. It does this with a diverter door in the air ducts called the Air Mix Door. A small electric motor called the Air Mix Door Motor moves this door.

You have 2 possible culprits - the heater control panel or the Air Mix Door Motor.

The FSM has a diagnostic procedure in the service manual. It is poorly written and difficult to follow, but that's all you got.

Section HA (Heat & Air Cond) page 50.
GET manual here - http://boredmder.com/FSMs/Nissan/Maxima/1998/

Page 50 is for the manual HVAC controls. I don't know which controls your car has. If you have the auto climate controls, run the self diagnostic that starts on page 70 and follow that.

 

That, we can do

Thanks for the quick reply! We've been through the auto diagnostic found on that exact page, we're still trying to figure things out, But it seems that it only told us we have a bad "PBR" valve, (-26) and a bad sun sensor, (25). I think what we will end up doing is just that, stuffing rags in the air outlets until we can get the car to a tech and tell them what we found.

Again thanks for the quick and precise reply, It's exactly what we needed.

 

Don't worry about the sun load sensor code. The self diag will automatically throw that code if you don't have at least a 55w shop light sitting over the sun load senor when you enter self diag. Its your PBR.

 

The PBR is built inside of the air mix door motor. Be prepared for a shock when you get the repair estimate...

Air mix door motor - old one on right


.

Air mix door motor opened up. PBR is in the left side, bottom middle, next to the motor. The real problem is the contacts for the actual motor itself, not the variable resistor (PBR). In the right half, the contacts for the motor are attached to the white gear. The contacts are made of copper, but they have developed the green corrosion that copper gets and the electricity can no longer can flow.

 

Nice pics Dennis. Don't have this issue yet but I see its starting to come up for people with digital climate controls.

 

Good fix.

 

The motor is the same regardless of which type of climate controls you have. The motor in the photos is from my 97 GXE with manual controls.

 

What I posted is not so much a fix as just information. I suppose you could clean the corrosion and re-assemble the motor but you need to be extremely careful when you open the motor.

That half round gear in the right half needs to be in a very specific relationship with the PBR variable resistor for the air mix door to work properly. If you get them out of sync, the air mix door either won't open all the way or close all the way. There are no instructions for doing this.

 

Oh I didn't know what. So it is better to replace this then. Has anyone ordered this from the dealership? If so, how much did it cost?

 

I'm seeing three different part numbers, 27732-40U00 ($67 @ Courtesy) shows for 02/94-05/98 production date, 27732-40U01 ($67 @ Courtesy) for 05/98+, and 27732-2L901 ($60.35 @ Courtesy) just shows 06/97+.

Not sure the difference or compatibility between the 2L901 and 40U0x parts, best to call and order by VIN.

 

I'm glad I found this thread as I too have the same problem, except that on my 99 SEL the air mix door is jammed in the full cold position and thus I have no heat at all! I called Courtesy Parts, a local Nissan dealer, and Autozone and all have told me incredibly that for my VIN the part is no longer available. I couldn't believe it as this is a critical component without which my auto climate control is useless! They did say though, that there is another year model that is available. Had any of you guys called around to confirm this?

So, can I use an older year air mix door motor on my 99 SEL? Also, how difficult is it to replace? It looks very tight under there. Did you use any special tools?

 

This is not good if that part is no longer available. I will also call up my Nissan parts guy to confirm with him and report back.

 

Replacing the motor looks like it would be fairly simple if you could get the ECU out. I couldn't figure out how to get the ECU out when I did my 97. I asked on the org here and no one answered me. People do it with engine swaps, so it can be done, but I couldn't figure out how. I could not find any procedure on how to either get the ECU out or how to replace the motor.

I pulled the dash out, but that didn't give me the access I mistakenly thought it would. Nissan used Phillips head screws to hold the motor on. If they had used hex head, you could take the motor off without removing anything else.

 

Just to update, I contacted my dealer yesterday and the manual ones are still available for $80 before my discount and was able to locate 2 in the US.

 

Looking for air mic motor for 99 maxima n can't find one anywhere. Can anyone help?