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Discussion Starter · #1 ·
Perhaps something to do with the present Mrs B. ,but I have noticed the windows misting when ACC is set other than 'Auto'. 'Off' is obvious, but I would have thought 'Econ' followed the same air path as auto, just with the aircon pump off. In this weather, the heater is on, & the chiller unit bypassed anyway?

Out of curiosity, mainly.

Steve
 

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I guess chiller unit same as Air Con evap box. The air still goes through this with Air Con off it just doesn't get cooled by the evaporator as the Compressor is not running. When Air Con is running the air is cooled and if below it's dewpoint which is usually the case moisture will condense out into the evap box (sorry chiller unit ) This usually drains away but if the drain pipes are blocked resides in the system and then gets reabsorbed by the air and causes steaming on windows.
Of course there is nothing to stop the windows becoming steamed up with the engine stopped and occupants in the car.
 

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Originally posted by steveb:
[qb]In this weather, the heater is on, & the chiller unit bypassed anyway?[/qb][/b]
The air still passes through the "chiller unit" to condense the water out of it, and is then heated so you get warm, dry air. Great for demisting.
 

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Discussion Starter · #5 ·
But presumably non-a/c cars are able to keep the windows clear without the benefit of reduced humidity? (equiv to econ mode?)

Mustn't say 'chiller box'
Mustn't say 'chiller box'
Mustn't say 'chiller box'
 

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Originally posted by steveb:
[qb]But presumably non-a/c cars are able to keep the windows clear without the benefit of reduced humidity? (equiv to econ mode?)[/qb][/b]
Yes, although it can take a long time and on some days can be nearly impossible, if my past experience is anything to go by. However, SAABPILOT is correct in that a blocked drain can cause misting up. Also, a not-uncommon problem with the 9000 is a leaky heater matrix which will mist up the windows too. Any smell of antifreeze in the car?
 

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I've got the same problem, one CSE steams the windows when aircon turned to ECON, our other dosnt. However, if I leave the aircon switched off for a time and open windows etc once the initial misting is clear its no problem. So for some reason the evap box on one of them must hold water/condensation more than the other. To check recirc flap (mines stuck but in open position), set fan to max, close all doors and windows and see if there is a strong stream of air out of the rear vents up the side of the hatch pillars - if not the re-con flap is stuck closed hence the same air is being recirculated around.
 

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Discussion Starter · #8 ·
Done some checks - on the move, no difference between 'Econ' & 'Auto' - steaming up is really only when stationary/crawling traffic.

I replaced the matrix last year & also checked recirc valve operation. 2 tips I had - 1. the large drain tubes from the plenum chamber into the engine bay are really for water coming through the air intake, hence clogging with dirt, leaves etc. There is also a tiny drain tube from the evaporator unit which is very difficult to get at to clear. 2. When replacing circlip in recirc flap control arm, tie a thread to the circlip - when it drops into the bowels of the chamber, you can retrieve easily.

Steve
 
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