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Discussion Starter · #1 ·
re-post to save pulling out any more hair!!!!!
Up to the recent hotter weather, 1996, 2.3 LPT CSE working spot on. hot weather arrives, car suddenly starts overheating as shown on temp guage. Running at 9 O'clock, then rapidly jumping up to the red, then dropping down then up again in cycles, each time showing a little hotter. When it reaches the hot level, my A/C compressor clutch does not engage and so cold air!. let it cool and hey-presto all working fine. This has no bearing on driving conditions and the auto fan seems to cut in and run as it should, including for about 20 mins after the car is switched off!
Any thoughs chaps?

Alun
 

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Alun, it's possible that the system recognises the high-temperature condition and shuts of the A/c compressor as running this will only make things worse, or it's also possible that the compressor gap in the compressor clutch has worn too large and the clutch isn't engaging when the under-bonnet temperature is very high.

However, these are secondary to the more serious problem of the engine overheating. If the fan is working, perhaps the thermostat is faulty. Have you tried anything so far to fix the overheating?
 

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Discussion Starter · #3 ·
i have not tried anything at all yet as i thought i would get opinion first. My thoughts are thermostat initially and take it from there, change to a 82 deg unit possibly?
 

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Alun, you cold try an 82 deg thermostat. I have one in my '96 CSE and an 89 deg thermostat in my '96 Aero. I see no difference in the temperature gauges, even in the recent warm weather.

I don't think the thermostat opening temperature is much of an issue in the UK climate. I only fitted the 82 deg one to the CSE because that's what Euro Car Parts sent (I was replacing the coolant and thermostat as a matter of routine).
 

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Fitting an 82 deg stat is normally something that us tuning heads do, in order to start moving rapidly heating coolant away from the head as soon as possible. The downside of it is potentially slightly worse economy.

It sounds to me like a sticking stat- does turning the heater on full drop the temperature- if it does then that's the most likely cause. If not, compared to other things it's a relatively cheap fix to do.

If it doesn't, then that suggests the stat may be OK and there's summit else afoot- as I recall it's a tri-state device and under extreme heat it doesn't allow coolant though to the heater matrix, but makes sure it's all flowing through the radiator which is the more efficient heat exchanger.

Mark
 

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Discussion Starter · #7 ·
i will take your advice and replace the thermostat, however......the A/c cutting out when the engine is hot is due to cluth wear???? how is that adjusted on the compressor. I do not know the make of the compressor but on the outside of the pulley it has three circles that look like balance weight (they are not though) if that is an indicator

Alun
 

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For an explanation of the problem and the solution, have a look for "Adjusting the air conditioning compressor clutch gap" on my web site: http://www.electricbbs.com

Of course, it may simply be that the system doesn't allow the compressor to run when the engine is overheating.
 

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Discussion Starter · #9 ·
ok, i will change thermostat first....at block end of top hose i presume??? Does the cooling system need re-pressurising or just topped up? if it needs pressurising how is that best done?

Alun
 

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You need patience with this one....after removal of thermostat housing cover (2 bolts), you will lose some coolant but just fill up after; if using genuine SAAB tstat, make sure bleed hole on plate of stat is at the top, position carefully with new rubber seal, thoroughly clean the mating faces of the housing and tighten to the required torque...remember aly components! The enabling works to open the housing cover take more time then the replacement itself!
 

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Discussion Starter · #12 ·
I did see that the top hose dissappears into the back of the head and is not immeadiately accessible........oh for a Morris 1000 !!!!!!

Thank you for your assistance

Alun
 
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