Z32 1990 Heater Woes, Help please

[rkubara]

I have the first generation Auto Climate Control system on my dead stock, beautiful collectors 1990 TT and cannot get heat, only slightly warmed air. I have placed a clear tube in line with the coolant to the heater core and see coolant flowing perfectly. But just in case I flushed the system with CLR Metal Cleaner then radiator cleaner. CLR Metal Cleaner does an amazing job at cleaning heater cores as it does not damage aluminum and it only needs to be pumped through for a few minutes. And yes flushing it afterwards is important and not ever had and damage the thin metal core. The heater core is OK.

I operated all the Climate Control diagnostics and the air flow switches as it should. All sensors are reporting the correct temperature, roof, floor and outside. The roof fan is spinning and I cleared all dust. Every diagnostic setting does seem to work but it there must be something I am missing as the AC works and will blast cold air, but I cannot get hot air even in diagnostics mode.

I suspect there is a door that deflects the air movement between the AC core and the heater core and that it is not moving from the AC core position. If I am correct then it is one of 3 things:

1) The Auto Climate Control system is not sending a signal to that motor.
Replace Auto Climate Control module?

2) The motor to move the door is not functioning.
How do I check this and if needed, replace the motor?

3)The linkage from the motor to the door has broken or come loose.
How to I check this?

I have removed the glove box and lower dash panels to the right of the heater system and cannot see any access to the above, all motors and linkage on this side activates.

I am hoping with your input, I can remove the steering wheel, driver's seat and access the heater area from the driver's side and source my problem. But then again, maybe it is my Climate Control module?

Please offer any insight you may have.
Thanks
Ron

[Ace2cool]

Oof, you have an extremely difficult task ahead of you. You are certainly on the correct path. I would say the CC module probably isn't the culprit in this case, as those were exceptionally simple, unlike the later generation.

The mix door is gonna be basically in the dead center of the dash. Here's a good thread with a how-to in the last post.

dash-removal-for-actuator-motor-replace ... 10267.html

It's not the "correct" way to do it, but it beats the crap out of removing the dash.

[rkubara]

Thank you Ace2Cool for your reply. The link you provided is for a Infiniti QS56 truck, are you suggesting it is the same procedure, or just that it is possible to access the door linkage via the center council?

You seem to be confirming there is a mix door/flap that directs the flow to the AC or heater core and that there is a motor and linkage which is likely my problem.

But I still do not know where it is located or what it is called; is it the Air Mix Door, Mode Door or Intake Door that is my problem? A schematic diagram would be ideal or even a part number so I know what I am looking for and where. I have the service manual but not certain what I exactly am looking for which door/motor/linkage.
Also, which diagnostic mode should be activating/switching it? Or maybe there isn't one?

Thanks
Ron

[rkubara]

Is there a way for me to manually move the door/flap to the heater position for the winter until I can do the repair? If so how to I access and do this.
Thank you

[rkubara]

I have been reading past posts on this topic and it has helped me understand a bit more. But none of the photo links on these posts work anymore so there still is missing bits for me. I have accessed the system via the radio and drivers side and when using system diagnostics it does seem like all the actuators that I can see move. Yet there still is no air flow coming through the heater core. I am wonder if there is a door I cannot see that directs air through the core and that it is not working.

I just cannot find enough info, photos or schematics to fully understand how it works so I can confirm what exactly my problem is. If I have to pull the dash, I want the repair parts on hands and at this time, I do not know what those repairs parts are.

In the meanwhile, how do I manually adjust the doors/actuators to get the system to have warm air flowing?

[rkubara]

Just finished putting it back together after hours of learning how it works. I got the engine up to temperature, opened the door that is accessible via the center council/radio removal via the diagnostics tool and I can clearly see the heater core. I used a laser digital thermometer and read the temperature on each horizontal bar of the heater core. The top 4 bars are all at 37C, the bottom 4 are at the ambient temperature of my a garage which is 10C today.

So I now think the heater core and AC core are the same unit, top is heat and bottom is AC. There must be a door/flap on the other side of the heater/AC core that directs air flow either to the top of the core or bottom and mine is stuck on the bottom. If anyone can confirm this is how it works I appreciate it.

If I am right, which motor/actuator controls that door/flap, where is it located, what is it called, can I remove it without taking out the dash and what is the part number?

Now if someone can tell me if I can manually move that door/flap to the upper section of the core and get heat until I am ready to take the dash out?

[Ace2cool]

Sorry, yes that was just a thread that I found that was the simplest and most concise explanation of how to get to it. It's kind of a pain.

http://www.nicoclub.com/service-manual? ... zx/1990/ha

Here's a diagram on page 2 of the air flow and the locations of all the mix doors. (and the positions they should be in to perform certain functions) Page 4 shows an overall system layout. The mix door, judging by the diagram, should be on the front bottom of the heater core unit. The IPB backs up this assumption.

https://parts.nissanusa.com/nissanparts ... &siteid=14

The way the system works is that the air passes through the cooling coils on the left, then air gets either directed through the heater core or around it via the mix door, and then the mode doors direct it from there. What determines if the cooling coils are cold or not is whether or not the A/C compressor is activated. Hope this helps. Take photos if you can, in order to help future searchers out!

[DCaff300ZX]

Be sure to check the heater core out as well, very commonly they fail slowly from blockage at the intake area as it's down low and the sediments settle around it and in the lower cores reducing flow, and eventually rotting through the bottom and leaking all over the floor. My '90 NA was similar to yours for about 5 years before the leak finally occurred and the problem got solved accidentally by the new core, and correct coolant flow.