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Coming off my heater hoses or off the control valve is this thin line. I have no idea where it plugs in to. Can someone help me. Here are a few pictures. from the heater hose on the bottom. up around lands up on top ends here. I have no idea where to plug this end into. What is this line used for?
77 vette with air.
That is the vacuum supply hose for heater control valve ,it runs from valve to your A/C and heater controls in dash .
Steven
Thank you for your answer and help. So do you know where exactly it plugs into the heater controls in my dash? And what if I just don’t have it plugged in does it hurt anything? I would like to attach it though.
It would require dash removal to repair it.
All those heater control vac lines worked fine rolling down the assembly line. Not so much after that.
Engineers should have used a thin steel cable to actuate that valve instead of vacuum.
Vacuum is at a premium on Vettes with all those requirements: Headlites, trans, pcv, hvac, dizzy, vapor canister, etc-etc.
You can do what most of us do and simply remove the POS valve completely. NAPA sells a manual shut-off in either 5/8 or 3/4 hose barbs. $27.
Open it in the fall, close it in the summer.
The real problem right now is that vacuum line is broken, causing a vacuum leak. You can pull the passenger side dash panel, the one with the map pocket. Behind it you will find the switch on top of the heater box that sends vacuum to that shut off . You can unhook the vacuum switch. you will see when the door is swung to close off heat it hits this vacuum switch. Unhook it and plug it.
Or. and much better. Look at a HVAC diagram for your 77.
(Yes I have one too). And get everything working properly!
I agree with all of the above...
You need to plug the Black vacuum line at the connector for the hot water shutoff vacuum switch that is on top heater box...
Red Arrow photo below...
A shortened golf tee would be my first choice for a plug...
If you purchase one of those heater control panel vacuum kits you will need to enlarge each hole in the firewall rubber grommet(s) so the new hoses will pass through.
Yes there are 2 grommets, a smaller one for the plenum actuator.
Before you even think about any of the above repairs, get a vacuum reading off of the carb to see if it's even worthy of repairing.
I see you have modifications on the engine. You may not have enough vacuum to operate the valve anyway.
With my cam, I am lucky to have eleven inches of Vac, (downhill with a tail wind)
Yeah I just had the dash out replaced all the bulbs headlight switch,etc. Put all new ducking fixing any leaks. So I’m used to having the dash out a few times. I just didn’t know where this line hooked up onto. I didn’t replace my heater core or anything didn’t need it so but I appreciate everybody giving me their input. Yeah I know this car runs on vacuum. I just replaced all the vacuum lines for the headlights. That was a fun job. I will experiment more with it later on today.
[QUOTE=HeadsU.P.;1605420046]It would require dash removal to repair it.
All those heater control vac lines worked fine rolling down the assembly line. Not so much after that.
Engineers should have used a thin steel cable to actuate that valve instead of vacuum.
Vacuum is at a premium on Vettes with all those requirements: Headlites, trans, pcv, hvac, dizzy, vapor canister, etc-etc.
You can do what most of us do and simply remove the POS valve completely. NAPA sells a manual shut-off in either 5/8 or 3/4 hose barbs. $27. Here is a picture again of the POS valve going up to a hose barb
Do I have to remove the POS valve if I already have a hose barb on it? So do I need not to worry about that vacuum line that comes out of the valve and goes into the firewall. The one I’ve been talking about.
In the rare event that the original cheap plastic brittle tubing is actually a vacuum leak, then yes, by all means cap it off.
As far as the manual shut-off valve: I ran new heater hoses, then down by the firewall the new valve is spliced in. Out of sight. I still have easy access twice a yr.
You can tap into either heater hose that's why they are sold in 5/8 or 3/4 at NAPA. But you could just remove your original and splice into that area.
The new valve has barbed ends already.
That’s good to know,so,I can shut it off,since I live in SC,I would never drive it in cold weather,unless Inhad to,and any time throughout the year,it’s not like we have two weeks of just cold weather anyway,and I have seen many days 70 degrees in December here.now air,you have to have 100+ degrees,oh,and that’s not considering the humidity.lol....Is one of the heater hoses plug into the intake,if so could I just remove that and put a plug in my intake,or does it need to circulation.
In the rare event that the original valvescheap plastic brittle tubing is actually a vacuum leak, then yes, by all means cap it off.
As far as the manual shut-off valve: I ran new heater hoses, then down by the firewall the new valve is spliced in. Out of sight. I still have easy access twice a yr.
You can tap into either heater hose that's why they are sold in 5/8 or 3/4 at NAPA. But you could just remove your original and splice into that area.
The new valv. e has barbed ends already.
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There are already new valves that were installed in the heater hoses. My question is does that mean that that vacuum line is dead I don’t have to worry about it I don’t have to reroute it back into the firewall or anything I’m trying to find where it goes. Or should I just capital off because I’m not sure if vacuum is coming out of there or not.
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There are already new valves that were installed in the heater hoses. My question is does that mean that that vacuum line is dead I don’t have to worry about it I don’t have to reroute it back into the firewall or anything I’m trying to find where it goes. Or should I just capital off because I’m not sure if vacuum is coming out of there or not.
Post #6 will answer your question. ANYTIME the motor is running you "should" be creating a vacuum.
The Black vacuum hose at the rubber connector is ANYTIME Vacuum
Plug Black hose at the vacuum switch rubber connector on top of heater box.
Post #6 will answer your question. ANYTIME the motor is running you "should" be creating a vacuum.
The Black vacuum hose at the rubber connector is ANYTIME Vacuum
Plug Black hose at the vacuum switch rubber connector on top of heater box.
line?
