I have a 87 trans am and I installed a ac blower and it blows perfect for the defroster on the windshield but won't work on the dash vents that blow towards you!! When I was installing the blower I notices that it had two hard lines in the engine bay on the firewall, I didn't hook those up because I didn't know where to hook it up. Can that cause the problem? I think it's two vacuum lines that's on the fire wall but I don't know where to connect them. Please help!!

 

It has two lines coming from passenger side firewall and it looks like wires but there not I think there vacuum lines that control the ac doors. Do you guys know where too hook them up?

 

vacuum hose from the hard line to the heater control valve and from the manifold to the hard line going to the heater controls.

without them, you wont be able to switch from defrost to vents; you need vacuum

 

Here's a picture of the heater control valve

 

But it has two vacuum lines. Where does the other one go?
And where can I buy the heater control valve?

 

Can I take the vacuum from the vacuum canister?

 

You can buy the valve from Advance/AutoZone/or any parts store relatively cheap;around 20 bucks, I recently bought one.

The one line comes from a tee from the plenum and vacuum caniser(ball in the drivers fender by the battery)to a small check valve to the hard line in that harness by the pass firewall. The other runs from the hardline on firewall harness to Heater Control Valve as shown in the photo I attached earlier.

 

My car didn't have a/c or heat nothing when I bought it. I went and bought a blower and blower box put it in got a heater core and ran hoses from the intake manifold and back. It works great but just blows threw the defroster vent. What's the heater control valve? I'm so confused

 

Subscribed.

 

IROCgiraffe, this is either gonna get bad, worse, or repaired. He didn't mention that his HVAC was GONE when he bought it! So, on that note, back to square one.
I'll look for a diagram of a complete hose/routing combo thingie and see what we can do. Mercy!

 

OK, Start with this.



You will need to go to the store and get the hoses, Heater diverter valve, and clamps to get the system "back to original".

Then we'll work on the vacuum line/lines to control it.

 

Thank you so much it's making some sense now lol... Do I realy need the heater control valve to make it switch from defroster to vents? Can't I just plug the vacuum line that goes to it? Is the heater control valve needed?

 

Without it, you will have hot coolant flowing to the heater core all the time. It diverts flow so it wont; it's less than 20 bucks; where are you located?

 

no mine I hear a hissing from the climate control panel when it is on, so I know it's a vaccuum leak that is not allowing the flap to divert the air from the blower to where I want it.... my heater core is currently bypassed due to it leaking, but my vaccuum line to the heater valve is still attached, so I doubt it's the heater valve under the hood since it control coolant flow, not the air direction.

 

Correct IROCgiraffe; 2 hard lines..........1 straight to the heater bypass control valve for LIQUID FLOW, and 1 line from vacuum source from plenum/vacuum ball to operate the heater "FLAPS in the dash. Like I said, "back to original". He don't NEED it, but he needs the OTHER line to operate the FLAPS for the vent

 

I gotcha!

 

I'm located in South richmondhill ny. Do you know what line I would have to hook up to make the flaps in the dash work? I really don't mind having coolant flowing threw the heater core at all times. But will that effect the coolness of the a/c?

 

UMMMM, Yes, cause your fan blows across your core without the bypass door working. As for the line going to your flaps behind the controls in the cabin, you will likely have to try each one. You have a 50/50 chance, so your odds are neutral.
You could have a helper pull on the lines under the hood in the harness while you feel for them moving at the controls.

hook up one from the rear of the plenum straight to one or the other hard lines one at a time, start car and select VENTS. If it doesn't shift from defrost, try the other hard line, it SHOULD WORK, unless that plastic rubber hose connection behind your controls is messed up and leaking. If its leaking, you will here it hissing like IROCgiraffe mentioned. A little dab of silicon will fix that

Once figured out, you will still need a "T" to go to the plenum and over to the vacuum ball.

I wanted to know where you were cuz we'll celebrate when YOU fix it. Of course, thats gonna be a long drive for me!

PS:SEE RED EDIT

 

Lmaooo ... Where you at!!? I would love too meet up with the master ac tech!

 

haha, Huntsville Alabama, 930 miles south of you! Master ac tech........NOT!