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Volvo 700, 800 and 900 series Volvo 740, 760, 780, 850, 940 and 960

Thread: 1994... 940..non-turbo vacuum leak under dash Reply to Thread
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  Topic Review (Newest First)
09-01-2010 01:58 PM
1994... 940..non-turbo vacuum leak under dash

Hi to all,
I have a vacuum leak under the dash, when you accelerate the ac/heater blower slows down or appears to. I think what is happening is when you accelerate, the engine requires more vacuum and there is not enough to hold the dash diaphragm engaged and therefore it reverts to default which is "defrost/floor". I have checked the diaphragms I can see on the drivers side under the dash. The dual one checks OK on one port but unable to hold vacuum on the other one. Disconnected this one (plugged hose) and tried to pull vacuum.
Connected hand held pump to hose on dash side of line check valve.
I can draw about 5 inches of vacuum but it leaks down. Can crimp the line feeding the system under the dash after it is (reduced to new kind of hose) and can draw 25 inches of vac. and it will hold.
I am unable to locate the valve bank under the dash. I have taken the glove box out and it is not under there..
There has to be a valve bank because you have different colors going to each diaphragm.
If someone can point me in the direction of the valve bank in this auto and how to get to it I would greatly appreciate it. By the way this happens only when accelerating , the air stops coming from the dash registers and goes to the floor and defrost vents which is "default for Volvo" Sorry for the long post

After further reading I am beginning to think I do not have "Climate Control"
I have three controls....."Blower", "Function Selector", "Temperature Dial" and a recirculating button, and AC on/off button. I do not know if I would have a valve bank or not with this setup. All my different color hoses to the diaphragms may be coming from the "Function Selector" switch. Can anyone help me out here? Thanks in advance

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