V60 Dual-Zone to Tri-Zone Climate Control: Adding Rear Seat Air Vents?

[Sven’s Owner]

Thanks. I’ll have to check the code again, I thought it said something about the rear but I could’ve been mistaken. But it actually got pretty warm here today and the AC came on and was working fine as far as I could tell.


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[IMAY2023]

After retrofitting rear heated and ventilated seats I tested this to be able control rear seat heating and ventilation from the center display "Rear climate control" 
Changing the setting "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC  enables the rear climate control under the climate control main page. Option appears at the top tabs of the climate control screen. 

However, it breaks the climate system. 
CCM throws DTCs 
1) missing temp sensors on the rear floor air vents (under each front seat) 
2) missing temp sensors on the rear console air vents although 339 SECOND ROW CENTRE VENT is set to 01 without
3) missing actuators for opening and closing the floor vents. 

In addition to DTCs, 
When you change the output vents from the center display, it does not do anything. In fact, no air coming out from any vent regardless which ones you choose. 

There are 3 types of rear seat heating switch. 
1) Basic one that has only two buttons controls only heating level for each side. 
2) Digital, controls both air vent speed and heated rear seats.  This switch is turned on only when  "175 HVAC VARIANTS"  is set to 02 HVAC large 4 zone ECC. 
3) Digital, controls both air vent speed, heated and ventilated rear seats.  Do not know if it turns on without setting  "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC.  Because I could not find a used one to buy and test it. 

At the moment, I installed the basic button "1" above so at least I can use the heated rear seats without breaking the climate control. 

Is there anyway to activate the rear climate control part on the center display without messing up the CCM. In order words, trick the CCM not to activate 4 zone while activating only on center display?

[Joe558]

After retrofitting rear heated and ventilated seats I tested this to be able control rear seat heating and ventilation from the center display "Rear climate control" 
Changing the setting "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC  enables the rear climate control under the climate control main page. Option appears at the top tabs of the climate control screen. 

However, it breaks the climate system. 
CCM throws DTCs 
1) missing temp sensors on the rear floor air vents (under each front seat) 
2) missing temp sensors on the rear console air vents although 339 SECOND ROW CENTRE VENT is set to 01 without
3) missing actuators for opening and closing the floor vents. 

In addition to DTCs, 
When you change the output vents from the center display, it does not do anything. In fact, no air coming out from any vent regardless which ones you choose. 

There are 3 types of rear seat heating switch. 
1) Basic one that has only two buttons controls only heating level for each side. 
2) Digital, controls both air vent speed and heated rear seats.  This switch is turned on only when  "175 HVAC VARIANTS"  is set to 02 HVAC large 4 zone ECC. 
3) Digital, controls both air vent speed, heated and ventilated rear seats.  Do not know if it turns on without setting  "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC.  Because I could not find a used one to buy and test it. 

At the moment, I installed the basic button "1" above so at least I can use the heated rear seats without breaking the climate control. 

Is there anyway to activate the rear climate control part on the center display without messing up the CCM. In order words, trick the CCM not to activate 4 zone while activating only on center display?

I'm working on something with some similarity, now. I am basically retrofitting my own version of the AliExpress kit; I have two 90mm case fans drawing air conditioned air through tubes from the ducting in front of the center console, and am using a factory vent with the touch screen controls. That switch uses LIN to communicate with everything else. T   he simple buttons you referenced have a different PID than the touch screen, and the HVAC variants option is what controls that. Long story long, I am working on an arduino based interceptor that will read the applicable values from the touch screen switch and relay to the car what it expects to see. I'm also using that arduino to ingest the fan settings so that I can control the speed of the fans that I retrofitted.  

   

[IMAY2023]

After retrofitting rear heated and ventilated seats I tested this to be able control rear seat heating and ventilation from the center display "Rear climate control" 
Changing the setting "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC  enables the rear climate control under the climate control main page. Option appears at the top tabs of the climate control screen. 

However, it breaks the climate system. 
CCM throws DTCs 
1) missing temp sensors on the rear floor air vents (under each front seat) 
2) missing temp sensors on the rear console air vents although 339 SECOND ROW CENTRE VENT is set to 01 without
3) missing actuators for opening and closing the floor vents. 

In addition to DTCs, 
When you change the output vents from the center display, it does not do anything. In fact, no air coming out from any vent regardless which ones you choose. 

There are 3 types of rear seat heating switch. 
1) Basic one that has only two buttons controls only heating level for each side. 
2) Digital, controls both air vent speed and heated rear seats.  This switch is turned on only when  "175 HVAC VARIANTS"  is set to 02 HVAC large 4 zone ECC. 
3) Digital, controls both air vent speed, heated and ventilated rear seats.  Do not know if it turns on without setting  "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC.  Because I could not find a used one to buy and test it. 

At the moment, I installed the basic button "1" above so at least I can use the heated rear seats without breaking the climate control. 

Is there anyway to activate the rear climate control part on the center display without messing up the CCM. In order words, trick the CCM not to activate 4 zone while activating only on center display?

I'm working on something with some similarity, now. I am basically retrofitting my own version of the AliExpress kit; I have two 90mm case fans drawing air conditioned air through tubes from the ducting in front of the center console, and am using a factory vent with the touch screen controls. That switch uses LIN to communicate with everything else. T   he simple buttons you referenced have a different PID than the touch screen, and the HVAC variants option is what controls that. Long story long, I am working on an arduino based interceptor that will read the applicable values from the touch screen switch and relay to the car what it expects to see. I'm also using that arduino to ingest the fan settings so that I can control the speed of the fans that I retrofitted.  

Thank you for the info. 
I know, REAR CONSOLE SWITCH MODULE RCSM  is operating on LIN connection to the IHU and different types of switches uses different LIN signal to turn on/off. 
I wired the switch connector to the IHU and my both switches work if I set the corresponding configuration.  I have the digital with heated seats (not ventilated) and simple switch. 

I am not planning to retrofit rear air vents on the rear console or I don't care about controlling the fan speed, controlling the fan speed would be just nice to have bonus for the kids to play with. 
I can control the rear seat heating with the basic switch. What I do care about turning on/off the rear seat ventilation. So, either I find and use the attached panel or find a way to enable rear seat climate control on the IHU without effecting the CCM configuration.  The CCM must still think it's 2 zone climate so that it does not try to control rear vents and complain about the rear vent temp sensors.  
Can you share more details about the  arduino based interceptor?

[paunionutz]

Why don't you wire the 3 temperature sensors, and install them in the air vents under the front seats (2 in left vent and 1 in the right), and you can activate the 4 zone climate?

[IMAY2023]

Why don't you wire the 3 temperature sensors, and install them in the air vents under the front seats (2 in left vent and 1 in the right), and you can activate the 4 zone climate?

First of all, there are four of them and not three.  One under each front seat (L&R)  and 2 for the central console rear vents (L&R) . 
The problem is each sensor goes directly to the climate control unit which is located on the HVAC blower behind the dashboard, via car's two main body harness connector. 
So, it's not possible to wire the four sensors without actually pulling out the dashboard.

[paunionutz]

So you can install  2 sensors under left seat, and 2 sensors under right seat, to read the same temp. I don't exactly how is at V60, but i've changed CCM module at  XC90, and XC60 who had some problems and i managed to do it without remove the dash. The module has only one clip that hold it, doesn't have screws or something. To make more room, you can remove the airbag and the right upper air duct (has 2 bolt)

[IMAY2023]

So you can install  2 sensors under left seat, and 2 sensors under right seat, to read the same temp. I don't exactly how is at V60, but i've changed CCM module at  XC90, and XC60 who had some problems and i managed to do it without remove the dash. The module has only one clip that hold it, doesn't have screws or something. To make more room, you can remove the airbag and the right upper air duct (has 2 bolt)

No, it's not that simple because sensors are at least of the problem. The major problem is the missing dumpers, CCM freaks out because of the missing dumpers and it messes up the whole air vents. Air flow settings becomes useless,  vents for the windshield does not work at all. 

Anyway, I doing something else completely. 
The way the climate control operates is quite different on new VOLVOs. 
You have the center screen, rear climate control (either heated rear seats button or digital one with FAN speed), IHU and CCM.
Center screen and the rear climate control are connected to IHU via LIN. (IHU is the LIN master) 
IHU is connected to CEM, VCM via FlexRay. 
CCM is connected to CEM via CAN BUS (low speed 125kbps). 
Logic says program a button that sends LIN command to IHU to turn on the rear seat vent. But there is a catch, LIN master (IHU) would not respond to a LIN slave ID (the controller)  if it's not been initiated by the master. Even if you send the correct command syntax somehow, MASTER would drop it. 

So, what I am trying to do is this. 
Listening the Low CAN bus while the car is in 4 zone mode, turning on the rear seat ventilation from the IHU, capturing the command sent to CCM to turn on the rear seat ventilation. Then replicating the same command from a the sniffer device while the car in two zone climate mode. 
In theory that should work.  I already tested on the bench and I can capture the CAN communication and replicate the commands. 
The next step is listening the CCM what it has to say :-)

[suprnowa]

So there are two types of blowers for 2-zone and 4-zone air conditioning?
is it possible to add an air duct to the rear of the 2-zone blower,

[IMAY2023]

simple answer is "No" unless the hvac unit is replaced.
The 4 zone has 3 types.  T8 models, T5 and T6 and xc90. 
T8 (sedans) do not have center rear console vent out but sides and under seat vent outs are controlled independently. 
T5 and T6 (sedans) have  have center rear console vent out, sides and under seat vent outs are all controlled independently. 
XC90 similar to  T5 and T6 sedans plus they have additional blower motor for the third row seat. 

In order to completed the retrofit, 
each vent out has its own temp sensor. needed to be added and wired to the CCM. (under seat and center console or side (T8 sedan) ) 
In order to control the rear temp and air flow 4 missing actuators should be added and wired to the CCM.  

You can find a used complete 4 zone HVAC and add the center too but it's very expensive job.  I would consider retrofitting it only if I ever need to replace the HVAC unit because of of a leakage or something like that.