306 air conditioning/climate control

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lowpugV2

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I'm sure it's been covered but search has failed me.
Is there a bullet point checklist when testing a 2001 306 xsi AC system?
Apart from a leak test and pressure switch test are the other electrical components likely to stop the system working?
 
Yes, the fan blows and the heater works. Ac lights come on and the compressor kicks in but then airflow drops and some weird noises from under the dash happen..
 
I don't really know how the Cooled side of the system regulates itself, so just throwing this idea out there.
Faulty flap controlling air flow over the evaporator. Maybe a busted drive gear on the flap.
 
The cooling side is controlled by the thermostat which is connected to / controlled by the dial at front of dash, eg temperature.
 
Is there a climate control ECU managing the whole system like there is in the 405? I only finally discovered this elusive part hiding at the bottom of the A/C enclosure behind the centre console. Mine's a bit stuffed - no temperature regulation, only full hot or cold. Seems to be a common problem from my research.
 
405 maybe. its like the 205, just a closed loop system that just turns off and on with some hysteresis. Unless its got some smarts which most likely came with the variable compressors in later models like the 306, its a lot smarter / more complicated.
 
As far as I know there is an ecu controller. It's linked to the interior temp sensor in the roof and theoretically keeps the interior at the set temp. The car in question is a 2001 xsi so is the last of the 306 years.
 
I'm getting the impression that if the big mechanical parts are fine then I'd better get familiar with a multimeter!
 
Give me a few weeks and I will have one (306, 2002 model) as well. To investigate but to complicate things its a convertible so no sensor in the non existent roof.
 
Last edited:
Stuey said:
Shane (Double Chevron) and Robmac are pretty good generically with a/c but prob not specifically with the 306.
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Hmm, good to know. By the way, I don't have this car yet, but have looked at it. A very nice China blue xsi... With near perfect paint! Only real downside is the 250,000 Kay's and no ac!
 
Matthew said:
405 maybe. its like the 205, just a closed loop system that just turns off and on with some hysteresis. Unless its got some smarts which most likely came with the variable compressors in later models like the 306, its a lot smarter / more complicated.
Click to expand...
2001 306's have the variable output compressors and has a more advanced control system, as in it don't switch the cold on and off to regulate temperature, but actually varies the compressor output.
Given that the system works otherwise, and that the air flow is physical cut off accompanied with noises when cold air is requested, would suggest that the computer is working fine, but something mechanical in the vent system has failed.
I've never had one apart, so I'm not familiar with how the cold air is mechanical regulated, but there is a flap in the evaporator box referred to as AIR CONDITIONER REDUCTION. This would be my bet as to the cause. The drive motor that controls it looks to be located on the bottom right side of the evaporator box. Not sure how easily accessible it is.
 
The penny drops, these dash boards have electric motors to drive the flaps, the noises you hear are those motors. They are not working so no air gets to you. I have a dash and airbox out of a 306 and if you were here would show you. As mentioned above they are held in with screws and can be removed / replaces. Good luck.

If required I can get a picture of this location for you.
 
gromzx said:
2001 306's have the variable output compressors and has a more advanced control system, as in it don't switch the cold on and off to regulate temperature, but actually varies the compressor output.
Given that the system works otherwise, and that the air flow is physical cut off accompanied with noises when cold air is requested, would suggest that the computer is working fine, but something mechanical in the vent system has failed.
I've never had one apart, so I'm not familiar with how the cold air is mechanical regulated, but there is a flap in the evaporator box referred to as AIR CONDITIONER REDUCTION. This would be my bet as to the cause. The drive motor that controls it looks to be located on the bottom right side of the evaporator box. Not sure how easily accessible it is.
Click to expand...

Genius, I reckon that's it. Thanks!
 
Matthew said:
The penny drops, these dash boards have electric motors to drive the flaps, the noises you hear are those motors. They are not working so no air gets to you. I have a dash and airbox out of a 306 and if you were here would show you. As mentioned above they are held in with screws and can be removed / replaces. Good luck.

If required I can get a picture of this location for you.
Click to expand...


If you could ( as long as no hassle) I would appreciate it. If I get this car fixing the ac would make it a rare beast.
 
Of course, home late and its dark, might have to wait until weekend? How desperate / in a hurry are you?
 
I'd go with the heater flap thesis. Either the gears of the flap shaft itself. Mine is broken all along the shaft. Put the endoscope down to see what was wrong, but haven't motivated myself to take our the dash yet.

Sent from my LG-H815 using Tapatalk
 
Matthew said:
Of course, home late and its dark, might have to wait until weekend? How desperate / in a hurry are you?
Click to expand...

No hurry, whenever suits. Haven't decided on the car yet. Thanks!
 
Here it is, not too hard but up a little in front and too the right of the blower fan under the
dash.

From on top, you will not see this but it shows both flaps controlled by motor
IMAG1256.jpg

From in front, motor is the grey / silver thing held in by a few screws.
IMAG1255.jpg

Easy decision really, its fixable and if the price is right?
 
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