Heater problems...

[UR2H]

My 77 280z only blows cold air and only out the front vents.

First of all I have my dash off so I have everything in clear view. Also my car is equipped with a/c (i think).

Okay to start I think I have a leak somewhere with my vacuum lines since I only get air from the front vent no matter what I select on the control panel. I have replaced all the hoses with new ones so I'm guessing maybe one of the vacuum pods or even my canister is leaking. Is there a method for me to test for a leak? Or could my vent problem be something else?

I do notice the vacuum pod on top of the heater control valve looks a little corroded.

As for the heat problem it has to be either the heater control valve or the heater core or both right?

When I move the lever from hot to cold on the control panel the heater control valve itself moves up and down but from what it looks like IMO it might not be opening up all the way. If the valve is frozen does that mean IT DOESN'T MOVE AT ALL or can mine be labeled frozen as well?

Lastly how do I know if my heater core is clogged?

Both the inlet and outlet hoses from the heater core get hot but I don't know what that means because if these hoses get hot, doesn't that mean the heater core should be hot in which case I should be getting at least some warm air?

I'm lost. Any advice would be greatly appreciated. I need warm air and a defroster. Thanks.

[FrankenScamp]

Could b the vac pot. Our 76 has 1 pot on the pass. Side and another on the drivers side right up against the box above where your right leg would b in the driver seat. That pot on ours failed and wouldn't allow the heater door to open thus there was just constant cold air from the front vents and no defrost. Find the lever that this pot controls and manually move it, maybe unhooking the pot will help. It'll force the air thru the floor vent and up to the windshield.

Hope this helps!!! Keep us posted......

[IdahoKidd]

My 77 still has cable controls to the flappers and theromostat. Am thinking it was 78 that they went to vacuum and all the troubles. What is the production date (on door jamb) of your car?

[IdahoKidd]

Pages AC 8, 9, 10 in the factory service manual have good illustrations. They show a vacuum set up. My 10/77 does not have this, but it also does not have ac. Perhaps the difference.

[UR2H]

My car has 3 of those vacuum pots, one on the drivers side next to the box which indeed controls the floor and defroster vent. One on top of the blower which controls the vent to allow fresh air and one on the passenger side next to the box where the heater valve is. Do you know which function this pot serves?

When I manually open either the fresh air door or defroster door using the latch for each respective pot, I can hear air leaking from that same pot that failed on yours. Also one thing I should add is that neither door opens when I use the control panel which is why I think I must have a vacuum leak somewhere. So does that leak sound mean that the pot is bad?

[UR2H]

Production date is 4/77. I don't have the factory service manual. I have the Chilton's. Maybe I should opt for the factory....it only makes more sense that I should. But the heater valve is controlled by a cable. When I go from hot to cold on the controls I can see the valve tilt up and down but even though it tilts, it doesn't look like it's moving that much. I'm wondering if the valve might be frozen closed in which case I would need a new new one. Would you know a source where I can get one?

[Moonshine]

Appears as if we are working in the same area

HELP - MY PROBLEM/QUESTIONS??? - my heater was eliminated by the previous owner who looped the heater hose from the water pump to the block -and bypassed the heater coil all together - in researching further w/ helpful steps from this sites threads I did a total teardown and diagnosed a few problems under the dash - it appeared that the curvy heater hose was replaced by a straight one that made a kink in the hose dis-allowing the anti-freeze to flow freely creating a leaky weak spot around the valve - besides 2 clamps not being placed correctly - so all in all the previous owner got lazy and just eliminated the heater - i had the heater coil re-tinned (no leaks) - checked all the vacuum tubes - replaced all the 5/8 heater hoses w/ new - in putting everything back together i snapped the copper hosing off the stem (photo attached) - i took the stem out and carefully re-bored w/ drill bit

QUESTIONS -

1) - the stem where the copper hosing is attached - it seems to have no relavancy as a valve and appeared to be just welded to the top of the stem - can i just re-weld to existing hole w/o worrying if the hollow copper tube is flowing correctly ? what does this stem/hollow tube do??

2) In reading a few threads i found that a few have eliminated the heater valve w/ another one from other vehicles and/or just replaced w/ a gate valve in the engine compartment - & when u want heat u just turn on the valve - but i see no diagrams & it seems as if im back to square one w/ no flow to the heater coil - i am not the one to "jerry rig" but to stick to the OEM parts - but do want heat anyway possible

Any input/photos/diagrams would be appreciative