Vacumn Leak - need help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

slamd58 · 03-16-2005, 02:54 AM

Guys I have a vacumn leak behind the dash. It gets worse when the top air/heater control is moved from inside air to outside air. I have traced it from a vacumn canister in the engine bay (bolted onto the heat/a/c exchange box on the left side of engine bay). I can remove the line in the engine bay and the leak stops. I am assuming this line goes to the heater/ fan unit under the dash. However I can't see where it goes...... to much stuff up there. Does any one have an idea of where this line should attach? Anyone got a picture of there dash out but the heater box in place (if that is possible).......

thanks for any help

p.s. got all the leaks fixed on my blazer and had some engine work done...... (the 454 is smooooooth now). Also, had the muffler shop extend the pipes out to the back of the blazer instead of dumping underneith..... It is much quieter and sounds awesome.... I know I'm disappointing some of you who work on your trucks..(and actually still love doing it...I'm jealous) ...been there done that..... don't have the time since I just bought the Coldwell Banker R.E office here in K-falls....

vtblazer · 03-16-2005, 06:59 AM

Your correct, it goes to the heater/AC control panel.
The controller had three tit's on the back that accept the hoses, that's where it needs to go.
I want to say the middle one but can't remember for sure.
If you can't get under enough to see the back of it, there's only two screws holding in the controller, just remove those and it will drop down.
Check the owners/shop manual's too, thay should show where engine vacuum will go.

slamd58 · 03-17-2005, 12:02 AM

VTBlazer - thanks for the info. I was looking at the controller today and saw the two bolts underneith the controller that looked like it held them on..... could this also be the reason why the fan switch is harder than heck to move from one position to another.....or is it just a bad switch?

Is there any chance that someone could post the page out of the shop manual that show where the vacumn lines go? I don't have one yet, but is now on my list of things to order.

03-16-2005, 02:54 AM	#1
slamd58 <- Determination Pays Off Join Date: Dec 2004 Location: Klamath Falls, OR Posts: 77	Vacumn Leak - need help! Guys I have a vacumn leak behind the dash. It gets worse when the top air/heater control is moved from inside air to outside air. I have traced it from a vacumn canister in the engine bay (bolted onto the heat/a/c exchange box on the left side of engine bay). I can remove the line in the engine bay and the leak stops. I am assuming this line goes to the heater/ fan unit under the dash. However I can't see where it goes...... to much stuff up there. Does any one have an idea of where this line should attach? Anyone got a picture of there dash out but the heater box in place (if that is possible)....... thanks for any help p.s. got all the leaks fixed on my blazer and had some engine work done...... (the 454 is smooooooth now). Also, had the muffler shop extend the pipes out to the back of the blazer instead of dumping underneith..... It is much quieter and sounds awesome.... I know I'm disappointing some of you who work on your trucks..(and actually still love doing it...I'm jealous) ...been there done that..... don't have the time since I just bought the Coldwell Banker R.E office here in K-falls.... __________________ 1958 Chevy Pickup 350/350, PS, PB, Tilt, A/C, 4 wheels Discs, 17" Wheels. Full Leather Interior - SOLD 1972 CST Blazer 454/400, A/C, 4" lift, 35's, Double wall top

03-17-2005, 12:02 AM	#3
slamd58 <- Determination Pays Off Join Date: Dec 2004 Location: Klamath Falls, OR Posts: 77	VTBlazer - thanks for the info. I was looking at the controller today and saw the two bolts underneith the controller that looked like it held them on..... could this also be the reason why the fan switch is harder than heck to move from one position to another.....or is it just a bad switch? Is there any chance that someone could post the page out of the shop manual that show where the vacumn lines go? I don't have one yet, but is now on my list of things to order. __________________ 1958 Chevy Pickup 350/350, PS, PB, Tilt, A/C, 4 wheels Discs, 17" Wheels. Full Leather Interior - SOLD 1972 CST Blazer 454/400, A/C, 4" lift, 35's, Double wall top

03-16-2005, 06:59 AM	#2
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,537	Your correct, it goes to the heater/AC control panel. The controller had three tit's on the back that accept the hoses, that's where it needs to go. I want to say the middle one but can't remember for sure. If you can't get under enough to see the back of it, there's only two screws holding in the controller, just remove those and it will drop down. Check the owners/shop manual's too, thay should show where engine vacuum will go.



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