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AC blowing hot only - air mix motor (code 26) question
So after going the FSM diag procedure, my only problem is a Code 26 (PBR circuit). I looked under the dash and I could see the air mix motor functioning when I changed the temp from hot to cold (auto climate control) but only hot air still came out
My question: is the PBR within the air mix motor the only thing that could be wrong, or has anyone had mechanical issues w/ the actual door that the motor actuates? We're about to have about 6 months of 90°+ weather he're in TX so I really don't mind having it "always cold" while I look for the right part to fix it, especially if it just means removing AC vents/controls in the center and fiddling with that door.
What you videoed is not the Air Mix Door Motor, it is the Mode Door Motor. The Air Mix Door Motor is located above the ECU. Follow the wires that are below the motor you videoed towards the front of the car. You can barely see it from the driver side foot well, it is more easily seen from the passenger side foot well.
The PBR is built inside the Air Mix Door Motor, it is not a separate item.
here is a view of the Air Mix Door Motor from the passenger foot well.
Here is the Air Mix Door Motor opened up. In the left half, about the middle, is a small gear. It is mounted on the PBR. If you look on the right half, there is a white half gear that has some metal fingers on it. The metal is copper and you can see green corrosion on the fingers. That corrosion is why your motor doesn't work.
Last edited by DennisMik; 04-25-2017 at 11:17 PM.
Reason: fix broken photo links
Looks like the power cable I ran to my amp may have caused it to stick - hopefully it didn't break. Will know once I drive it later - it was blowing cold now but the car is cold.
I did replace my air mix motor. Since it sits above the ECU, removing the ECU would give you enough room to remove the motor. Only problem was that I couldn't figure out how to remove the ECU. Others have done it, but I couldn't figure out how. I posted the question here, but I didn't get an answer.
I removed the dashboard thinking I could get the ECU out that way, but couldn't. But with the dashboard out, I ended up cutting the mounting ears off the motor with a hacksaw blade. If Nissan had used hex head screws to attach the motor, I could have done it without removing the dash.
What year is yours? My actuator/arm connection looks different. Looks like 27732-40U00 is the part # I need for my 10/96 build date.
I went through the entire FSM procedure and luckily once while I was watching I saw the actuator move but only whine after that as I switched between 65° and 85°. After a lot of poking around at the motor arm with long needlenose pliers I was at least able to get it stuck on cold rather than hot.
If you could clean the copper fingers, and bend the fingers a tiny bit more, you would be good to go.
But when you take the motor apart, you have to be aware of the strange construction.
When I just pulled the motor apart, most of the gears fell out because the half moon gear is underneath 2 of the 3 gears in the top left of the photo above. There is a definite alignment so that the motor stops at the end of the travel and reverses direction. If I remember correctly, the 2 halves of the motor did not want to separate easily because of the gears being sandwiched (which I didn't know at the time), so I used brute strength and ignorance to separate the halves and then had to retrieve the pieces.
Maybe if you just separate the halves slightly and then stick something thin and flat in to hold the half moon gear, you might be able to hold the half moon gear in the side with everything else.
My bad to re-hash a thread from 6 months ago, but I had to write something because this job sucks! '97 I30 with a bad air mix motor (only blowing cold air all the time...did the fsm diagnostic on the climate control system and got -26 pbr short circuit). Had to order the new motor / actuator from Nissan Parts Zone ($60) because rock auto, ebay, and autozone had nothing.
Anyway, I'm in the middle of doing this job now, and there is no freaking way to get to the air mix motor without removing the ecu, and moving the wire harness out of the way. I also had to take the glove-box out to undo a dash harness that patches into the main ecu harness. Long story short is that it took me the better part of 3 hours just to remove the failed air mix motor.
I honestly thought that this would be a half hour job, and it's going to take me the better pert of tomorrow to finish.
I my end up doing an official write up with pictures, but just wanted to complain and tell everyone that this job is a pain in the !@!#$ There is no space to work, and the three bolts that hold the air motor in place are not accessible unless you remove the ecu and have a special small ratcheting screwdriver (got mine from harbor freight for $2) to remove the ecu from its bracket and the air mix motor from its mount, and a long handle 10mm ratcheting wrench to remove the ecu mounting bracket from the body.
Damn this repair, I hate hanging upside down in the front seat.
I may actually install a remote start and car alarm system since I'm down here and wires and dash panels are exposed. Gotta love underestimating the time on a repair job!
I think I live for this %$^&; Nissan / Infiniti 4 ever!
Damn this repair, I hate hanging upside down in the front seat.
I may actually install a remote start and car alarm system since I'm down here and wires and dash panels are exposed. Gotta love underestimating the time on a repair job!
I think I live for this %$^&; Nissan / Infiniti 4 ever!
Originally Posted by bigd480
A write up would be awesome. Mine is rigged to max cold and I was planning to replace it before winter.
I had to do this to my 97, so I feel your pain. The only advice I can offer is to replace the screws that hold the motor on with hex heads. If you ever have to do it again, you can get the screws out without taking anything else off.
I finished the job this morning. I got working heat and a/c again!
Looking back, it was not that bad.
Much faster (about an hour) to install the new air mix motor and close up, then it was to tear everything apart and remove the old one.
Unfortunately, I didn't even think about hex screws for future repairs, but I still don't think that you can do it without removing the ecu and harness, as the harness blocks access to the two out of the three screws holding the air mix motor in.
I took some pics, so I'll go do a write up once I get some time.
Ever made that write up? Also, is there an easy way to just adjust it manually to hot or cold? Mine is stuck on hot and I live in Texas and it is summer.
You cannot adjust/move the air mix door manually unless you take the motor off.
Although maybe you could cut the arm off of the motor. However, you would have to be very careful that you don't cut/damage the arm for the air mix door itself. If you mess up that air mix door, it would be cheaper to buy another car.
Another, much safer thing you could do is take the hoses off of the heater core from under the hood so that no hot coolant flows through the heater core. You would have to buy a hose coupler to connect the end of the heater core hoses together.
Thanks Dennis. Yeah I had that idea about the heat. This would stop the hot air from coming, but still wouldn't give me cold air right? At this point I'd do just about anything to just get cold air. [Texas + Summer]
Think it would be worth it to take it to a repair shop? Or is something this difficult probably not gonna be worth the money?
If you unhooked the heater core hoses, then you would get cold air from the a/c.
Nissan has kind of a strange way of doing things. The way the air flows through the ducts is:
outside air --> blower motor --> a/c evaporator core --> air mix door --> heater core (or not) --> vents in dash.
Right now with the air mix door stuck and directing all the air flow through the heater core, the air is being cooled by the air conditioner, but then it gets heated right back up by the heater core.
The heater core water hoses (I assume that is what you are asking about) are accessed from under the hood. Open the hood and look at the windshield wiper motor that is mounted on the firewall on the passenger side of the car. Looking down the firewall just a few inches towards the center of the car from the windshield wiper motor, you will see a hose coming out through the firewall. A few inches directly below that is another hose coming out through the firewall. These are the 2 hoses for the heater core.
You will notice that you don't have a lot of room to work in in order to disconnect the hoses. It will be a pain in the butt. If you use too much gorilla power, you can snap the pipe off of the heater core that the hose attaches to. These pipes are a replaceable piece, done from inside the car... another real pain in the butt.
Changing the air mix motor is a pain in the butt, removing the heater core hoses is a pain in the butt and replacing the heater core hose connections is a pain in the butt.
Personally, I would just go ahead and work on the motor that needs to be replaced anyway instead of messing with the hoses.
Once again thanks Dennis. Found the hoses and connected them together. was difficult but only took about an hour with my step dad's help. I'm worried reconnecting them in the winter will be more difficult, but rather have AC than no heat anyway.
Julian I don't know where in Texas you are but last year I had my Air Mix motor replaced for $150 in Austin. The part was about $70 shipped from nissanpartszone.com back then.
bigd480, thanks for the info. I'm in Austin as well. That's good to know the price. I'm in LA most of the year and just come back and use this car when I visit. Now I know how much money to bring back this winter to get it fixed!
To remove ECU the 4 Philips screws should be removed: 2 from rear side and 2 from front side. But it will be still difficult to remove Air Mix Door Actuator. The next step is cutting out all plastic clumps holding electric cables on the ECU frame. Final step is removing the ECU frame: take out 2 (10 mm) bolts from rear side. There is no mount bolts for a front part of ECU frame (just pull out central plate by shifting frame back/rear). Someone may find useful to cut out some parts of the ECU frame. (Pictures attached) And use parts of the plastic rings (from 1/4 tube) for holding the 3 screws inside of holes of actuator. ECU removing ECU removing ECU frame removing ECU removing ECU frame/ECU removing ECU removing ECU frame move back Cut clumps Remove/cut some parts from a frame Actuator installed Used tools
03-17-2014, 03:22 PM
^-I assume this is normal operation. 
