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Discussion Starter · #1 ·
Hi all

I have a 9000 CSE which operated wonderfully until a few days ago. First the air con started to blow cold about two hours into a journey, now the heating system doesn't seem to work at all. Any suggestions?

Chris
 

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Discussion Starter · #3 ·
It has ACC. Worked fine. Then just blew cold air couple of hours into journey. Then didn't work at all. Then worked ok for about an hour but not to usual heat levels. Now nothing. No fan. Could it be the internal sensor as that was quite dirty and made a horrible whirring noise. Cleaned it up so no noise but still no heat or fan.

Thanks
Chris
 

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Discussion Starter · #5 ·
Originally posted by Mark B:
[qb]Please try the ACC unit's self diagnosis (checking) procedure detailed in the handbook.  This will tell you how many, if any, sensors are faulty.  Let us know. [/qb][/b]
Thanks for tip but afraid I don't have the handbook. Can anyone tell me the procedure?
 

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Had the same problem on my 1992 Carlsson. It turned out to be the heater/AC flap valve arm had snapped. It must be fairly common as Saab will sell you a metal arm that slides over the stub of the plastic arm and after that everything worked fine.
 

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Press the AUTO and <-> (bottom right) buttons together. The display will then change from temperature to "0", and the self check/recalibration process will start. If faulty sensors are detected, the display will change to 1 or 2 or however many faults are found. When complete, after about 30 seconds, the display reverts to show the set temperature.
 

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Discussion Starter · #8 ·
Originally posted by Mark B:
[qb]Press the AUTO and <-> (bottom right) buttons together.  The display will then change from temperature to "0", and the self check/recalibration process will start.  If faulty sensors are detected, the display will change to 1 or 2 or however many faults are found.  When complete, after about 30 seconds, the display reverts to show the set temperature. [/qb][/b]
Thanks for that - there are no faults. It may heater/AC flap valve arm as mentioned by Aeroguy. Any quick way of finding out.
 

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Take the plastic cover off the false bulkhead - bit between the base of the windsreen and the engine compartment. You can then see the heater control arm and flap close to the fan unit, change heat setting (get someone to do this) and watch to see the arm/flap moving.
 

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A similar question on the same topic. Could someone confirm that the ACC controls the temperature by mixing hot and cold air into the cabin. Does it ever switch off the flow of hot water from the engine to the heater matrix? The reason for asking is that mine is nice and warm at speed (50+MPH) but goes stone cold when slowing down into traffic or into town (even wit the system set to "Hi", but warms back up again if speed increases. When its blowing cold the return hose from the heater is cold. I do not know whether to suspect the ACCII unit or one of the sensors (fault code is zero) or the heater matrix (car done 140K). When I replaced the interior cabin sensor the temperature was all over the place.
 

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As far as I know air temp is achieved by simply mixing hot air from the heater matrix with cold air that has by-passed the heater matrix - there is no flow control on the heater matrix.

However, the engine cooling system is set up such that when things get hot (engine) all the coolant is sent from engine to radiator and hence no flow to the matrix. I'd look checking the engine cooling side of things and first call would be a new 'Saab' thermostat fitted the correct way.
 

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Adrian said:

However, the engine cooling system is set up such that when things get hot (engine) all the coolant is sent from engine to radiator and hence no flow to the matrix. I'd look checking the engine cooling side of things and first call would be a new 'Saab' thermostat fitted the correct way.

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I'm not sure that this is correct. Surely flow to the heater matrix is maintained under all conditions.

It seems to me that when the water pump is running slowly there is not enough flow to the heater matrix. Logically, this suggests an underperforming pump (unlikely as long as the drive belt is intact), or some from or restiction in the heater matrix or the associated pipework.
 

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I'm with Adrian. It's my understanding that somehow (possibly via a "tri-state" thermostat) when things get very hot, the flow is diverted more away from the heater matrix towards the radiator, on the basis that there will be maximum cooling available that way.
 

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Yep the Saab cooling system has a tri-state thermostat and I'm sure if things get hot all the cooling flow is diverted just to the engine/radiator. For this reason removing the thermostat on an engine with cooling problems will actually make the overheating worse. I solved this problem for a chap in France a few years ago - car overheating, he removes thermostat and car still over heats, I tell him to fit new thermostat and problem is solved.
 

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The car has had two new thermostats (to make sure it got the correct Saab one and that it was fitted correctly), the heater matrix was flushed and steam cleaned when the head gasket was replaced 2 weeks ago. This did not change the performance of the system at all.
 

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It seems that I must confess to stupidity, or at least not being awake before noon. I haven't got the manual here to check, but I suspect that the thermostat has a circular plate at the bottom. As it warms up, it opens the top to the radiator by moving the circular insert down, whilst closing the recirculation path around the engine by moving the circular lower plate down. In extreme conditions the thermostat will open fully and effectively block off the recirculation through the cylinder block, the flow going through the radiator instead. However, from memory, most thermostats only reach their fully open position at a fairly serious temperature, one which we are unlikely to see at this time of year, unless there is something seriously amiss.

Whilst I haven't been able to do a detailed examination of the pipework, I'm puzzled as to how the fully open thermostat closes off the flow around the heater (although this would obviously result in increased heat loss from the radiator). And what about the flow of coolant to the turbo? Surely that's not stopped?

Bubbles/Adrian, could you explain further please?
 

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Discussion Starter · #18 ·
Originally posted by Aeroguy:
[qb]Had the same problem on my 1992 Carlsson.  It turned out to be the heater/AC flap valve arm had snapped.  It must be fairly common as Saab will sell you a metal arm that slides over the stub of the plastic arm and after that everything worked fine. [/qb][/b]
Checked that now thanks, appears to be working fine. Any other suggestions?
 

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I missed this thread somewhere along the line,
First let me assure all that the thermostat is no differant than any other,Saab's own is better quality than most,when cooland is cold,'stat is closed,preventing flow to radiator,as coolant reaches operating temp 'stat starts to open.The stat will remain fully open during warm weather but will open and close to maintain temp during cold weather,the flow to the matrix is constant untill it is regulated by a valve either manualy or through the ACC.
I would suspect that ChrisM's problem will be either an airlock in the system or a faulty water pump,checking the belts would be worthwhile.
Try taking a heater hose off whilst the engine is running,if there is a good strong flow of water then everything should be OK,be carefull not to damage the heater hoses as one costs over £30.
 
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