Hey everyone, my 89 formy had the original 305 pulled in favor of a carbed vortec 350, my question is.....the ac work but only blows through the defrost like the heater does, i looked under the hood and one vacuum line runs to the egr valve satelite looking thingy and theres another vacuum line just sitting there, where do I run it? to the carb?

 

Yes if the carb has a vacuum port, that’ll work.

Or you can use any source of vacuum.

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Happy Racing!

 

thank you, i was thinking that but didnt want to mess anything up without asking, btw, nice signature

 

I have two small black flexible tubes coming through the firewall near the AC/Heater. What are they for and do I need to use them? I have a Ram Jet 350.

 

I dont know what they are for but I think they deal with vacuum for the ac/heater. one I think goes to the egr valve and the other to a vacuum on the intake. I think

 

Negative on the EGR connection, unless its a T fitting
between manifold vacuum, and the EGR controller.
(EGR valve should have a DEDICATED line from the controller.)

The 2 firewall vacuum connections are
-- input a vacuum source.
The dash control routes vacuum to the diaphragms that control
cabin air flow.
-- output to the heater control valve.
(A popular thing to rip out by the purists, to "clean-up" the engine bay.
in which case it should be sealed, or you'll have a vacuum leak
when you try to activate the heater.)

Off the top of my head, I can't remember how to identify which is which,
and I'm currently 300 mi's away from my project.

Good luck.

 

That is the best answer I have been able to find anywhere. Thanks.

Where is the heater control valve located? Perhaps I can use that to figure out which one is which. If I want the heat and AC to work as they orginally did, do I just need to connect both of them to vacuum?

 

thx for the hijack, lol just kidding, if I connect one of the hoses to the heater control valve and the other to a vacuum on the motor like on the carb will it cause the air to come through the normal vents and not the defrost?

 

Heater control valve is on the passenger side of the eng. compartment,
identifiable by three hoses conected to it. For TBI engines, one hose
comes from the back of the intake manifold, one hose comes from the
heater core through the firewall, & one hose goes to the radiator.
Its a vacuum operated valve that routes hot water either to the
radiator, or through the heater core. TBI engines have a similar
configuration, but I don't know the exact hose connnection points.

Connecting both firewall vacuum lines together will probably adversely
effect overall heat-ac control function. To supplement my original
response below, the (firewall) input vacuum source is connected to the
dash control, which routes the vacuum to various diaphragm controls
to direct airflow generated by the fan. So without input vacuum,
air will only go to the default location, which I believe is the defrost vents.

If you can post a picture of what you have, and what does/doesn't work,
I can probably help you get where you want to go.

 

Vortech got your response in while I was typing the response to jimc.

So Vortech, the not so short answer is yes, IF
-- you get manifold vacuum connected to the correct firewall connector.
-- the dash control switch still works properly.

As I sit here thinking, I recollect something about the firewall connectors,
before I had to repair mine. (Long story, )
Originally, these are hard hard plastic lines, with rubber boot connectors.
The longer line is the output to the control valve, and the shorter one
is the input, connected to a manifold vacuum source.
(To repair mine, I put small barb connectors through the firewall, and
will then use standard rubber vacuum lines.)

 

oh alright cuz everything is hooked up except one small vacuum line from the firewall which from what you say I need to possibly hook up to the carb then??