Series II - Vacuum leak in AC control system
#1
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Symptoms are that the system responds sluggishly when engine rpms are low, and when switching off there is a gradually diminishing whooshing sound lasting 15 - 20 seconds. The sound is from the area around the cold air centre vent.
Before I start dismantling anything, does the air blend box have to come out to access the centre flap servo?
Before I start dismantling anything, does the air blend box have to come out to access the centre flap servo?
#2
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Symptoms are that the system responds sluggishly when engine rpms are low, and when switching off there is a gradually diminishing whooshing sound lasting 15 - 20 seconds. The sound is from the area around the cold air centre vent.
Before I start dismantling anything, does the air blend box have to come out to access the centre flap servo?
Before I start dismantling anything, does the air blend box have to come out to access the centre flap servo?
Larry Louton
#3
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Thanks removed the crash pad and searched for the sound with a rubber hose acting as a stethoscope. The sound originates from an area between ac/heater box and bulkhead. Only thing I know to be there is the hoses an T-piece in connection with the ventilation fan flaps. The problem had to be in an inaccessible place. Next is to inspect with a boroscope.
Currently away from home so tool access is very limited.
Currently away from home so tool access is very limited.
#4
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Do you have friend that still smokes cigarettes? Remove panel from under steering wheel. The blower motor housing has a blue vacuum line going to it. Remove blue line and have your friend blow smoke into it. The smoke will find the leak. I bet that the leak is behind the radio. You will never see it with a boroscope.
Larry Louton
Larry Louton
#5
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Greg in France (07-21-2023)
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#10
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if this is a USA car, there is a check valve between two rubber lines hanging near or by the battery by the firewall. .
this check valve feeds the a/c Servo. If it gets stuck with debris, it interferes with the Servo operation.
Memorize the orientation of the check valve, it normally has an arrow pointing to interior of car, remove it and blow on it. Air should come out from one side only. If no air comes out from either side, or if air comes out from both sides, check valve is bad.
one possible remedy to free the ball inside the valve is to put it in warm water a while until any debris is loosened by blowing into it. Or just replace it.
this check valve feeds the a/c Servo. If it gets stuck with debris, it interferes with the Servo operation.
Memorize the orientation of the check valve, it normally has an arrow pointing to interior of car, remove it and blow on it. Air should come out from one side only. If no air comes out from either side, or if air comes out from both sides, check valve is bad.
one possible remedy to free the ball inside the valve is to put it in warm water a while until any debris is loosened by blowing into it. Or just replace it.
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Bill Mac (07-25-2023)
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