Heat valve control line

[Ricardo_france]

Hello.

I've some questions about the heat system on my '77 caprice.



The A/C works fine, but no heating (since I bought the car)

I've located the heater valve, but the vacuum connector is blocked by a screw. (1)



On the right side (near the blower box), I found 2 small vacuum lines (1 white and 1 brown).
How do I plug these 2 lines ?

Another question:
What's this part ?



Thank's for your help

[PeteA216]

These disconnected vacuum hoses are definately the cause of no heat. The black sphere is a vacuum globe, which acts as a vacuum "buffer" to help keep vacuum in the system even at WOT. This particular vacuum globe buffers the vacuum for your vent controls, switching from floor, to the main front vents, to the dash defrost vent. It's also likely it supplies the heater line valve with vacuum as well.

[silicon212]

The 'orb of nothing' as Blue Bowtie calls it (because it's a vacuum sump) connects between intake manifold vacuum (connects to a port on the intake behind the carb, a TH350 vacuum modulator line connects to the same fitting - this is called MANIFOLD vacuum as opposed to PORTED vacuum), and the underdash vacuum system that operates the various doors and controls on the A/C system.

The heater control valve is supplied with vacuum that is sourced from under the dash - it's usually a brown colored 'hard line' (plastic instead of a rubber hose). The white line supplies vacuum from the vacuum sump to the underdash network. You don't want to plug either of these if you want your heater to work as designed.

Part #1 is your heater bypass valve (as you stated),
Part #2 is your EGR valve, and
Part #3 is your EFE heat riser valve diaphragm.

Part #2 receives vacuum from a PORTED source through a ported thermal vacuum switch (TVS) on the pre-computer cars, and part #3 receives ported vacuum through a separate TVS.

On the computer cars, an electric relay replaces the TVS for the EGR.

[bobss396]

Not that you asked, but.. you didn't have to strip it to the bare block to get to your heater control parts.

Bob

[j cAT]

that engine needs rebuild. i think your heat problems are now the least of your concerns...

[Ricardo_france]

Thank's to all.

Some precisions:
My engine worked well, but some hydraulic lifters were noisy.
That why I opened my engine.

beuarkkkkk !!!!




The EFE valve ... blocked closed


Now, the engine is rebuild.

EFE and EGR were removed.