Understand Climate control system?

[jamie392]

My climate control system doesn't work properly. And before I can fix it I need to try and understand what components it has that make it work. Anyone with knowledge in this please help me

It is a 2004, so I believe it has the newer FSR. In auto mode, lets say I set the temp to 23, it will pump hot air and never slow down or shut off. Same with cooler temperatures, basically the auto function seems to do nothing. I can manually adjust the fan without a problem though.

I'm wondering how this auto function is supposed to work, and why there are the adjustment valves (hot or cold) on the center vents. If you have it on the hottest position (on the vent) but put the auto system on 16, it will still pump hot air of course because I believe the hot air valve is open, so how does the auto system actually blend the hot/cold air when it is a manual control?

Also is there a sensor somewhere in there to measure the inside temp? I heard I should hear a small fan but I never hear any noise after I turn off the car.

Thanks a lot I really need to try and solve this
Jamie

[JCL]

Before getting to the mechanical diagnosis, start with the operating discussion. This is how it is supposed to work.

Turn the air conditioning on (snowflake). Push the auto button so that not only the temperature is auto, but also the fan speed. Turn the centre vents to neutral (no red or blue dots). Set the recirc to auto. Now, see if it works. Turn the centre vents off (shut) if you like.

Now we add in the centre vents. The centre vents are not an absolute temperature control. They are better thought of as an offset control. If you have it set to 23 (I have mine set to 19, but that is another story), then the thumb wheel on the centre vents allows you to have a warmer or cooler flow on those two vents. They aren't a temperature control, they simply provide a slight offset. They aren't an automatic setting, but rather a manual override, and that is where owners get in trouble with them. One blue dot is one degree cooler, two red dots means two degrees cooler, one red dot is one degree warmer. This is designed so that with a comfortable temperature in the vehicle (automatically held by the AC control), you can have slightly warmer or cooler air blowing on your face. The problem is that if you set it to 16 degrees on auto, and three red dots, then the air conditioner will work hard to get it to 16 degrees, while the warm air in the centre vents fights it. It is an illogical setting.

See if the above works (as designed) before starting to diagnose any mechanical problems. The most common issue is that people have the auto control set to cold, with three red dots, or vice versa.

Good luck.

[jamie392]

thanks for the reply!

So now I believe the auto function is working but there is still a problem. I didn't realize that even though the "auto" button is lite up, that it will not work automatically unless you press it again and see the auto button pop up on the display. Now when I click that auto button the fan speed changes relative to the temperature setting.

The problem is, that with the AC button clicked, when I move the center vent dial to the middle position (no dots) the air is really warm. When I move it back to the 3 blue dots it is relatively cold, or cold enough that it is comfortable on a hot day.

As far as the AC system goes I had the refrigerant tested and there where no leaks and it was evac'd and recharged again anyways. Also, the AC compressor is kicking in and they said the system seemed to work perfect.

What would cause it to be on a warmed setting like it is doing?

Thanks again
Jamie

[JCL]

If the auto function is working, and there is sufficient refrigerant, but you find it more comfortable with 2 or 3 blue dots, then run it there. It may be that it has been warm out recently, and the system and ducting just needs to cool down to get to a steady temperature.

[jamie392]

The thing is that if I turn the center vent to the max cooling, then the floor vents + the rear seat vent still push out hot air all the time. But all the front vents seem to push out cold enough air. Is there some motorized valves in there that might have gone wrong?

[e30mpower]

Regarding the rear vents, are you sure that the temperature dial next to the vents is set in the blue range?

[jamie392]

Yup, it is set blue and blows warm. Just curious if there are some motors or valves in there that sometime go wrong or get stuck?