Climate control.
Left side blows hot air , right side blows cold air.
Tried self test Had "Flash rom unit error in control unit 41" message. After error was cleared out it did not reappear.
I suspect a heater blend door or air mix motor.
Does anyone know whether there is a relay or some kind of resistor that can be replaced.

Not looking forward to mess with HVAC and replace any of the motros.

Thanks
2006 infiniti m35

All our HVAC motors are bus. Only fuse is before the motors for the unified meter amp which drives the bus motors. Just replace the defective bus motor and you should be good to go.

@ Kirkland91
My 11 M37x is doing the exact same thing. It's out of warranty so I am on my own. Did you ever get yours fixed? If so, was it a door or motor issue or something else? Any help with this would be greatly appreciated.

Thanks

You never mention what you had the temp selected to. I assume both are set for cold. In that case have you checked the temp
Unit that tells the computer the current temp of the air in the car. The m can blow 90 on one side while 60 on another at least on a 2011 m. The g can't seperate the 2 sides like the m can.

Brian

Hi Brian,
I bought the car in August when it was still hot here in Iowa. The AC worked great, I rarely ever ran it on high. The first few times I used the heater I didn't notice anything strange, but since it has gotten colder with temps in the single digits I can run the heater on high with the temp set to 90 and even after 20-30 minutes it never gets hot inside the car. I noticed a small anti-freeze leak and assumed it was the problem so I took it to a local garage. They said the air relief plug on the radiator was loose and they tightened it up. I also had them flush the cooling system to relieve any air that may have been introduced. When I got the car back it still wasn't getting as hot as I thought it should and that's when I noticed the difference in the temperature coming from the vents. So, with the car fully warmed up (engine temperature gauge is in the middle between the H and C) and the temp set to 90 (both modes, single and duel), the vent left of the steering wheel is 125 degrees, drivers center vent is 120 degrees, the passenger center vent is 86 degrees and the passenger vent on the right is 77 degrees. Switching through the different settings (floor, bi-level, upper vent on/off etc..) yields the same result; much cooler air on the passenger side. If I set the temp to 60 it blows cold air and both sides feel the same, I didn't check the actual temp of each vent though. I called the garage back and he said it sounds like a bad motor in one of the mixing doors and the only way to test it is with the computer. I want to eliminate other possibilities before I spend the money on the diagnostic. I have checked the in-cabin temp sensor below the start button and it is plugged in and connected to a small hose that I believe goes to the other sensor on top of the dash. I've also pulled the glove box and made sure all of the electrical connections were plugged in.

Any ideas?

Thanks, Joe

Issue is resolved, however not sure how.
What I did was unplugged blower motor relays (located on the back side of fuse box, on the left side under steering wheel).
My friend has Infiniti M45, so I asked if I can borrow his relays from working car to see if problem is in relays.

Long story short:
relays were ok.
Switching relays did not solve problem immediately.
Looks like some part of ECU was reset.
Climate control started working fine the next day.

Glad u got it done. Sorry I didn't get your last reply so I didn't post.

But glad u got it fixed.

Glad I found this post... I'm having the exact same problem after the Compressor, evaporator were replaced.
Sorry to see you did not know for sure what caused it to start working. My guess is that an full ECU reset is the first thing to do, ensure that the BCU (Body Control Unit) also gets reset. Look at relays second.

Any thing else to try?

I am still having this issue with '06 M35x, and its over 100 where I live today!!!

Problem Recap: Compressor seized, had compressor, nozzles and evaporator replaced. Repeated testing shows no leaks/full recovery.
Since getting the car back the drivers side air temp is always 15 F or more degrees warmer!
the driver's vent is always 68F or higher; while the passenger side air vent can drop to 51F.
Been this way now for almost two weeks. Most recently, the repair shop did multiple full resets in multiple ways, no change. They're unable to solve the problem.

I have the car back now, did all the self diagnostics in the FSM, all passed.

I also tried the ATC trimmer adjustment (FSM ATC-62). No effect on the temp difference between the outlet vent sides.

Today, with the temp at 104 i the sun, car idling, using self-diagnostic mode 41 (full cold, recirc, low fan)
==> the passenger side was good, 55 F
==> the driver side was bad, 77 F.

The FSM does not have any more troubleshooting/diagnostic for this problem.
I am still struggling to find the problem. Any more suggestions out there?

Thanks!

Have you taken it to an Infiniti dealer or just mom and pop shop? Reason I ask is because the dealer has the Consult device which may be able to tell you more...at this point I think you've exhausted quite a bit of troubleshooting yourself...

Infiniti dealer would be the next stop, but I'd want to go somewhere that has a solad HVAC person, this is a weird problem.

Might do one more test: I'm thinking that I'll check the vent temps with the car cold and coolant flow to the heater core blocked see if this problem still persists.
If right still cools more than left when no heat in heater core, duct door positions and sensors don't effect output temp. Which means it is a problem with the evaporator (does not cool evenly( or its installation (air can flow around it on the left side).

If it is the evaporator is the problem than the car goes back to the original garage. Else it goes to Infiniti for more troubleshooting, etc..

Make sense?


.

block flow to the heater core

So I did my own added test beyond what's in the FSM by capping off the heater hoses.... I figured it would be lots of $$$ for an Infiniti dealer to debug - OK if it is an HVAC controls issue, but what if it was an evaporator problem that was outside of the norm? My justification: I needed to flush my cooling system anyways

Turns out it's an evaporator problem! The HVAC controls are all good
Now, has anyone seen an evaporator that cools mostly in one area, and not in the rest? May also be air outside bypassing the evaporator.

In any case, below is my write-up for the local shop.... pretty unhappy about the whole thing, this is wayyyy too much work on my part. And I won't drive the car this way in the hot late afternoon.


Note to shop:
============
I've left my Infiniti M35x to have the A/C repair work completed. The compressor, evaporator, and other components were all replaced a few weeks ago. The passenger side gets cool, the drivers side always is much warmer, though lower than ambient - your last round of troubleshooting was inconclusive, and I took the car back, and did some of my own troubleshooting.

HVAC System: All incoming air goes through one blower to a single evaporator. The air is split left/right after it goes through the evaporator... then doors open/move to control how much air goes through the heater core and to which ducts receive that air.
Per Factory Service Manual for HVAC (attached file atc.pdf ) see pages atc-37 & atc-38 for system diagrams

Problem: air on left (driver's side) is 15 +/- 5 degrees warmer than on the right (passenger) side of the car.

Question: Is the L/R temp problem associated with the ducting/interior hvac controls?

Test Approach: Eliminate heater so that the output temp of interior vents cannot be warmed due to HVAC interior controls/ducting or improper air flow through the heater core.

Situation: Disconnected/capped off the heater hose and testing the AC with engine initially cool, mid-seventies outside.

Testing: With heater capped-off and AC on, ALL measurements showed the driver's (left) side to be 15 degrees warmer than the passenger (right) side.
The test were conducted with the target temp HVAC system at 60 and 90 degrees, dual and non-dual modes - this made no changes in output temp when keeping fan speed the same, and ensured that the HVAC controls did not contribute to any temp differences.

Results Summary: With heat disabled, The lowest temp seen on the passenger side was just above 40 degrees, and on the driver's side just below 60 degrees.

Conclusion: Only the evaporator cause temp change in the incoming air.
Given that the Evaporator was indeed cooling the driver side air a small amount, the air on the left side included air that was not drawn through the evaporator, or the evaporator is not uniformly cooling the air going through it.

Note: If this evaporator core is defective, do NOT install another evaporator core from the same manufacturer. Best to have the OEM replacement part.


References:
Parts list and Diagram of Evaporator Assembly
http://www.orderinfinitiparts.com/parts ... mCallOut=1
Factory Service Manual for HVAC is attached

Update: the shop checked the evap installation (good) and sensors (not sure why) ... they're stumped, assume that the air exiting from the evaporator would mix enough be for the doors to the left versus right vents. I can't assume that that much mixing occurs in the tiny space between the thin directional evaporator fins and the vent doors. This does mean that air on the left comes out of the evaporator warmer than the right.

I came up with a new test, though. If I close down all the left vents, the increased airflow on the right side should be slightly warmer. And vice versa. Doesn't prove whether air is bypassing the evaporator OR the evaporator is cooling things unevenly.

They've offered to replace the evaporator. I notice the aftermarket evaporators are ~$65, and the OEM from Nissan is $375!!!
On the other hand, maybe the Nissan evaporator is copper, and the aftermarket one is aluminum? I want to find out.

Here is a page with some great pics of a used OEM evaporator:
http://www.ebay.com/itm/06-10-infiniti- ... f1&vxp=mtr

and page with a pic of a new UAC aftermarket evaporator:
http://www.ebay.com/itm/A-C-Evaporator- ... b6&vxp=mtr

I'll do a separate posting with more thoughts about uneven evaporator cooling (and copper versus aluminum).

I noticed this problem as well today. My car is still under warranty. I've also noticed an unusual blower fan noise. I will report back when I know more.

M37x2012 wrote:I noticed this problem as well today. My car is still under warranty. I've also noticed an unusual blower fan noise. I will report back when I know more.

Keep in mind your fix might not apply as your car is a different generation...but it'll be good to share the knowledge regardless.

was this problem ever resolved? update?

svard75 wrote: ↑

Fri Oct 31, 2014 5:53 pm

All our HVAC motors are bus. Only fuse is before the motors for the unified meter amp which drives the bus motors. Just replace the defective bus motor and you should be good to go.

Hi, could you pinpoint on where the hvac motors are located? I'm also not sure if you mean buss fuse by "bus" - I'm assuming so. I'm not as well versed on electrical, excuse the ignorance!
I'm having a similar issue as original poster - My Drivers side blows A/C fine for both sides, however for heat, only the drivers side gets heat and not the passenger. I wouldve thought this would be a blend door actuator on passenger side, but I'm not sure as the failure happened at 60k miles on my M37 (seems like early failure for the actuator based on how reliable infiniti's are!)

Thanks
Victor

The motors are on common circuits sourced from the HVAC control head. Because the power and communication are shared by all the devices involved, it's called a bus. If you disassemble a typical actuator, it's generally a "toy boat" brush motor with zillion-to-one gearing, so they aren't particularly hardy. When replacing it you should also make sure the problem isn't a sticky mix door, restricted movement will make those little motors fail very quickly.

PS - Dunno what year your M is, but you can find the location in the "Automatic Air Conditioner" (ATC) section of the FSM here:
https://www.nicoclub.com/infiniti-service-manuals

IIRC, I think on all the M's the passenger mix requires pulling the glove box and the blower unit.