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A/C not blowing out vents only bottom of dash (72 Olds Cutlass Supreme)
I have a 1972 Oldsmobile Cutlass Supreme and my air does not blow out my vents but sounds like it's blowing out the bottom of the dash. I checked behind my AC/Heat control panel and it looks as if a vacuum line is missing. However, I am not sure if that vacuum line controls the air to the vents and if so where does it feed from. I have attached a picture. Any feedback will be appreciated. Thank you.
There is a vacuum reservoir on the engine side of the firewall that looks like a black ball. There should be two vacuum lines connected to it: source vacuum from the intake manifold and another line through the firewall to the AC controls. If you lose vacuum on this, the air flow defaults to the heat (floor) position.
The flapper door that directs airflow among the bottom, dash, and defroster vents in the under-dash HVAC box is operated by a vacuum actuator bolted to the end of the HVAC box near the accelerator pedal. The vacuum switch on the control head is what supplies vacuum to this actuator, so without the hoses connected properly, the system defaults to floor-only airflow. I suggest you get a Chassis Service Manual and look at the vacuum diagrams in Chapter One.
Thank you for your help. After further investigation I realized that I do not have the Vacuum Reservoir at all. I will be ordering that today. Thank you Fun71.
Be very careful when removing an old rubber hose from the canister. I cut it down the center of the rubber hose, and then peal it off the plastic nipple. I broke one trying to pull the hose off, and learned an expensive lesson. Rubber hose is a lot less expensive than a new canister.
Thanks guys. Can you let me know which of these below will work? I was told by a summit rep that 47077 would not work for my car but this is the only part that comes up when i search for a Vacuum tank reservoir for that vehicle. Also, I found a different vacuum tank on ebay. I can't find a clear picture of one.
There are one-port and two-port versions of the vacuum reservior. Either one will work if connected properly. The two-port has a built-in check valve. The port with the check valve goes to the intake manifold vacuum tap, the other goes to the HVAC system. The one-port design requires an external tee with a built in check valve. Yours came with a two-port reservoir from the factory.
I bought the below vacuum reservoir and tried to see if it would mount up right, but it does not have enough clearance over the transmission dipstick tube. Oldspackrat do you still have any available?
Oldspackrat....thank you. I'm still worried about the clearance of my transmission dipstick tube. It appears that it sits up too high. I've looked at other 72 Olds motors and the transmission dipstick tube appears to be a lot lower than mines. Is there anything I can do about this?
Thanks guys. Can you let me know which of these below will work? I was told by a summit rep that 47077 would not work for my car but this is the only part that comes up when i search for a Vacuum tank reservoir for that vehicle. Also, I found a different vacuum tank on ebay. I can't find a clear picture of one.
Oldspackrat......looks good. Does it still function properly and can it be cleaned up with some soap and water? if so..how would I purchase this from you? Also, can someone tell me what the box is circled in red below? I have the adjacent black box (junction box) but not the silver box right next to the vacuum tank in the pic. Also, I called OPG and they told me that my vehicle came with either a 34 or 27 inch dipstick tube so I ordered a 27 inch (I hope this fixes the clearance problem). I measured the dipstick on the one I have already and it was 30 inches so i'm assuming this was not the correct dipstick and tube for my turbo 350 trans and for my cutlass. Thank you for the pics Oldspackrat.
... can someone tell me what the box is circled in red below? I have the adjacent black box (junction box) but not the silver box right next to the vacuum tank in the pic.
That's a voltage regulator. Presumably your car has an internally regulated alternator now.
ddd777,
I have the correct screws for the vacuum bulb. Pm me your address & I'll get them on the way?
LJ,
I have several of these & will make sure you get a functional one that will clean up just fine. I would start with the least aggressive method to clean it such as soap & water & a wash cloth. You can always try a plastic bristle brush if it does not want to clean up. As far as payment, I'll pm you shortly.
So I just installed my new 27" transmission dipstick tube and I still do not have enough clearance for the vacuum reservoir tank. The vacuum tank can mount up to its respective holes but once it does that it sits right over the dipstick tube with probably an inch clearance. Which makes it impossible to check my trans fluid because the tank would be in the way. Can anyone shed light on what maybe the problem? i was thinking about putting it higher up on the firewall but wanted to know would that be frowned upon if i used some self drilling nails to put new holes in the firewall so that the tank will sit higher than where it originally was suppose to sit. Also, can anyone tell me what is the correct height/length of the transmission dipstick tube that came with the 72 Olds cutlass. I'm thinking I need a 24 inch dipstick tube. Or just getting a flexible stainless steel one that mounts to the firewall but I would prefer the original look.
Last edited by LJ72Cut; September 19th, 2016 at 07:42 PM.
Does anyone have a clear picture of where the vacuum line that runs from the vacuum tank to the back of the manifold hook up? I know one line goes from the control panel inside the car to the tank but I was wondering where did the remaining line that hooks up behind the carburetor go. Thanks.
This is what I have readily available. It's an aftermarket intake but the important stuff is similar to the factory one.
I think the factory intake will also have a small vacuum nipple on a runner behind the carburetor for the air cleaner thermal valve.
How do I know what size vacuum line to use? Do they come in a pack with diff sizes?
Also, which vacuum line in the above pic do I trace through the firewall and place on the nipple of the vacuum tank reservoir (the black one or the white/black one)?
The vacuum reservoir similar to the one pictured below from your web link should be mounted on the firewall and have a small diameter vacuum hose (1/4" maybe?) connected to the nipple on the intake manifold labeled AC Vacuum Reservoir in the picture.
As for vacuum hoses, they can be purchased at the local hardware store. I am not certain of the exact size needed but if you have a caliper, micrometer, or precision ruler you can measure the diameter of the port and get a hose with that inside diameter. Or get a small piece of hose from the store and test fit it on the port. It will be the right size, too bit, or too small. Go from there.
If you don't have the reservoir above, once you get one you can bring it to the parts store and try hoses until you get the ones that fit on the reservoir nipples.
If you have on on the firewall, take it off and bring it to the parts store to try fitting the hoses.
Last edited by Fun71; April 27th, 2017 at 06:13 PM.
I have the vacuum tank (seen below) mounted to my firewall however where im assuming the AC vacuum reservoir is located on my manifold I don't have a nipple to connect any vacuum lines to. This is where the issue lies I don't know where to connect the nipple from the vacuum tank to the manifold.
I have circled where I assume the AC Vacuum Reservoir is located on the manifold but as I stated earlier nothing is here.
I have the vacuum tank (seen below) mounted to my firewall however where im assuming the AC vacuum reservoir is located on my manifold I don't have a nipple to connect any vacuum lines to.
I have circled where I assume the AC Vacuum Reservoir is located on the manifold but as I stated earlier nothing is here.
That's the boss where the coil screws on.
You can connect the A/C reservoir to any manifold vacuum fitting.
August 8th, 2016, 04:15 PM
