MCCNAT1959

O.K. Here's the rundown. My Z has manual (no vacuum) controls on the heater control valve. The valve was faulty when I checked it and water would only run through one way. I bypassed the valve with a connector and the heater core got hot and the heat started working. However, the water will still only run one way through the heater core. Is there such a thing as a directional heater core? The heat is working fine, the engine temp is working great, water (antifreeze) is circulating through the radiator and the block, so what is the purpose of the heater control valve? And before I get chastised for rigging it, this is just a temporary solution to get heat before it gets cold, if it ever will, here in TIDE country.

Thanks sooooo much for attaching diagram. Will check at first light and try to locate vacuum tank. Is that the white bottle referred to?

Thanks, but no white bottle. I have read the flaps are vacuum operated but cant find any vacuum hoses going through the firewall to the interior. Also I have checked all vacuum hoses arount the thermostat and intake and replaced one but still no heat.

Howdy, New member. I have a 78 280z without factory air and heater will not get hot. I have replaced the thermostat and checked all operating controls and vent flaps. They all seem to be working. Any suggestions?