Code1racing

Okay Guys here's my problem, I swapped out my L03 TBI for a Carbed 355. After the swap my HVAC system defaulted to defrost. I have found the vacuum line under the dash and have tried to hook it up to throught the intake, but nothing it still wants to blow through the defrost vent. Also I have no vacuum what so ever to the line going to the heater control valve. What is going on here? I do have a vacuum on the intake and there is vacuum going from the advance on the distributor to the carb. I cant seem to find a diagram for my year car and yes I have tried the autozone site. I still have my vacuum canister but I didnt think I would need It to control my HVAC. Do I?

Code1racing

Wow 20 views and Im the only one to have this problem. No one else has?

mos68x

I have this same problem and starting to get really frustrated since i need the a/c to work properly due to health reasons. been looking for a diagram myself and can't find one for my specific car

camaronewbie

There should be a vacuum line that has a check valve with 3 ports on it, 1 for the line coming from the intake 2 for a line running to the vacuum ball 3 line running into firewall to the A/C controls. The vacuum ball 'collects' vacuum for the A/C controls to use when there's little or no vacuum condition - the check valve allows the ball to 'collect' this vacuum, but keeps it from bleeding back out to intake when vacuum is low.

There's also another line on some cars that comes out of the firewall from the A/C controls that ran to the heater diverter valve - it either needs reconected to heater diverter valve or capped.

If the controls always default to defrost, you have an open vacuum line somewhere.

mos68x

Are you talking about the vacuum canister that sits up in the left side?

I finally found a diagram but still don't see anything on it that shows anything for A/C or anything behind the firewall. Since I have a carb now I've narrowed out most of them that have only to do with the TBI and won't transfer to a carb. I still have two lines at the firewall that I have no idea where to hook it up at on the manifold.

Do I need that ported vacuum thing that goes on the back of the manifold? I was looking for the older chevy ones so that I could have two lines instead of just one, but wasn't sure if that would work.

I think that taking out my canister to make room for something else has also caused problems with my fuel tank since it won't "top-off" anymore. But if I put it on I don't know where to hook up the vacuum line that goes the solenoid on the top of it.

camaronewbie

The canister - if cylindrical in shape, is the fuel evap canister - you can remove it, just run a length of fuel ine from that 3rd metal fuel line to somehwere out under the car, so in the event there are fumes or leakage from that hardline, they'll come out under the car where there isn't anything hot to ignite it.

What I was referring to is the vacuum ball - it is actually ball shaped, about 6 inches in circumference, and on my car is located under the driver side headlight - can't see it (headlight blocks from the top, and a panel blocks from beneath, but it's there. Like I said, you need vacuum to "accumulate" inside the ball, so that there will be vacuum available for the controls at idle when there's little or no vacuum. The check valve solves the problem, by allowing in essense vacuum to 'leave' the intake, but not to 'return' back through the intake.

You don't need the diverter valve if not present - I removed mine (was ugly) - now I just have warm coolant running through my heater core all the time - this may add a few degrees to the interior, but I ALWAYS ride with windows down and T-Tops out anyways - I removed my A/C all together 'cause I just don't like it. But you will need to plug or cap the second vacuum line if it's there to prevent a vacuum leak (not all cars had the second line as not all cars had the diverter valve).

You may have to get a vented fuel cap for the tank - can't remember if I did or not.

mos68x

I have my fuel evap canister completely removed, but it still shows connections to the rest of the vacuum system. I haven't done anything with that 3rd line, but that explains why my fuel tank doesn't want to "top-off".

As for the vacuum canister, I don't have one, I've had my front bumper cover a couple times and never seen it in that area.

I removed my heater diverter valve since it broke on me right in the Advance Auto parking lot. It doesn't really add much heat to the interior that I've noticed. But I am wondering though it that might be why my A/C doesn't feel as cold as it should. I am also wondering if it is because I didn't pull a vacuum on the A/C system before I charged it since the pump was replaced with another from the donor engine.

So one of the two vacuum lines that I have coming from the wire loom is for the diverter valve and the other is for the A/C controls...right? How do I figure out which one is which besides just trial and error?

camaronewbie

Trial and error is all I know to suggest - plug one and route the other to a vacuum source, make sure there are no other vacuum leaks, and see if the vents work properly - if not then reverse and try it. At least there's only 2 possibilities!

mos68x

that is true, lol

looked on ebay for a vacuum ball and at least they are only for $10 for the one that I saw

Can you get a picture of where it is supposed to mount so that I can put it in the right spot?

camaronewbie

If your fuel evap canister was on the driver side, it's directly under it.

mos68x

The reason that I was asking for a picture was because I do not have the threaded clips for the bolts so I have to figure out where to put some once I can get some for the vacuum ball.

camaronewbie

Sorry - I don't have a pic.