Colder air on passenger vents
 

As the title says, on the passenger side (I have a LHD car) the vents blow colder air than on the driver's side, regardless if for windshield, face or footwell vents, so for example when I set the temperature at 24°C, the air coming from driver's side is very well warm and on the passenger side it feels like it's set at about 20°C, the difference is definitely very noticeable. And to make matters even more complicated, the air vent behind the armrest (between the seats), always blows cold air, not even a bit warm even if temperature is set at HI. Any ideas how to fix this issues? Flushed the heater matrix but still no joy.

I suspect you will have a blocked matrix. The passenger side (left) on RHD cars tend to block up early, causing it to blow cold. I would imagine it would be the same as for the LHD, however I would have thought it would have been the driver's side on an LHD car that blocked first. I would not have thought the pipe work would have been different between LHD and RHD. :shrug:

Does the right side footwell blow cold for sure? The reason I ask this is because, I set mine to feet and windscreen, and when my car reaches the set temperature, it blows warm to both footwells, but warm only on the left side of the screen, and cool on the right side. This is a safety function to keep the driver alert. I wondered if you had changed your ATC control (assuming you have dual climate), with one from a RHD car (again I assume the ATCs to be different or programmable). :shrug:

The rear vents in the console come from the outside. Warm air only comes from below the seats if selected to be warm. Close the vents.

Nope never changed the ATC control, and yes footwell also blows cold on passenger's side.

And what do you mean that the air blowing colder on the other side is a safety function? How would that help in any way?

And as I've stated, I flushed the heater matrix and when finished, the water came crystal clear outside, also even when flushing it for the first time, the water coming out on the other side wasn't really gunky or dirty, it looked pretty well actually

The heater can be controlled thermostatically on both sides individually. The thermostat on the passenger side is not working.------:eek::eek::eek:


Apologies. I should have said the air flaps as Simon said on his post further down.


Getting old makes you say the wrong things for the right reason sometimes.---Lol.




Anyway, Merry Xmas.

Quote. CLF. ------but warm only on the left side of the screen, and cool on the right side. This is a safety function to keep the driver alert.


Sounds like a good idea to stop the driver dozing off but would that then not demist the drivers window ??

I must give mine a try to see if it does what you say.--Interesting.--;)

I looked up the ATC on Rimmers, and there doesnt appear to be a LHD or RHD variant (I am sure we would have read of issues with the SAIC versions if this was an issue).

The matrix could be still be blocked solid, and the water flush is simply passing through it? I had this issue on a car years ago when I used only water to flush. It eventually ran clear, but was still partially blocked, as it did warm up a little more, but not as much as it should have been. It took removal of the matrix, detergent and agitation to clear apparently (a garage did it on behalf of my grandfather - it was his car).

I do not know what the issue is, but blocked matrix is the most common issue for one side being cold.

Never actually considered dual thermostats. There would have to be some form of thermostatic control for the auto function to operate, of course. The drivers side air sampler is obvious, where would the passenger side one be?

It is supposed to keep the driver alert. I first read of it on this forum not long after I got the car in 2014, but never had much opportunity to notice it until a few years ago.

In the winter on a long drive it can become uncomfortable (for me) as I normally have short sleeves on all year round (I prefer not to drive with a coat on).

There is a way of bypassing it (without turning the heat up further), by using the bypass and switching off auto mode, I managed to do it a few times, but cannot remember exactly. When I first noticed it, I feared it was matrix related problem, but once I fiddled with the settings, warm air came through. It even does this whilst the ATC is switched off. The ram air effect, if the ATC system is turned off, the air flow appears to come in the form of which mode it was turned off in. Because of that, I imagine this safety function controlled by the flaps somehow.

I assume you mean 'mist' the windscreen, it doesnt, and wont whilst the ATC is operating and the AC is selected (providing the air dryer is functional), although on saying that, it may do on a warmer climate, but then the heat would not be on I am sure. I am not sure though what would happen with the AC off. The problem I have is my journeys are rarely more than 10 miles at a time.

Hi Galambosi,

Colvert has a good suggestion here although the "thermostats" he refers to are actually servo motors driving air blending flaps on each side. These mix outside air (cooled if the air conditioning is operational) with hot air drawn through the matrix to achieve approximately the temperature you've set on the control panel.

On your passenger side you'll see the servo motor (it looks like 3 fixing screws on the diagram) located immediately above the heater coolant pipes.

Have you carried out the ATC manual diagnostic check Galambosi? With the ignition key in position '0' press and hold the AUTO and air distribution buttons then turn the ignition switch to position '2'. If the RH temperature servo motor or flap is faulty you will see the code FC32 (ignore 21 & 22 which occur when there's insufficient daylight for the sunlight sensors).

Simon

Hello, I have the same problem on my 75 v6 2.5. The coolant has been changed recently with the cambelts.
The passenger side is cold but it heats only at 28 or on HI on the ATC control.
I checked the pipes of the heating matrix and they are both hot.
What do you think?
Have a good day

Hello Brahim, both heater pipes can become hot without hot water flowing through the passenger side of the matrix.The flow is in parallel streams top to bottom. It seems you have a matrix that's possibly air-locked from the recent coolant change. I assume it was OK before this work? If so, the first thing to do is to look at bleeding any trapped air from the system. This is discussed frequently on the forum and you'll soon find the details (also in the Haynes manual and RAVE).

If this is an older problem, the matrix is probably silted up on the passenger side.
The fix is discussed in this thread.

TC

Hello, thank you for your answer.
I don’t know if the problem was there before because I bought the vehicle a few weeks ago.
I’ll try to purge the system if there’s air.
I looked at the engine bulkhead: is it possible to disassemble the matrix by unscrewing the hoses next to the master brake cylinder?
good evening