78 280z

My lines through the wall and in and out of the heater core are hot. Fan blows cold and only from the center vent. flaps close when it is on def. but never a change in the flow from the center. The car has factory air but p.o. doesnt have a belt on compressor so I guess that went some time ago.

Where do I start??

In my 1978, I had a similar problem. At the firewall on the passenger side in the engine compartment, you will find some small vacuum hoses. On my car, one of them was split. Since these provide vacuum to make the entire heating/cooling system switch panel work, there was no heat. Seems all of the moving parts in the system are actuated by vacuum. Have a look at the hoses, I bet that is your problem.

Good Luck!

I believe you asked this question in another thread all the suggestions and diagrams are there. http://www.classiczcars.com/forums/showthread.php?t=32310

Thanks Guys, I just realized. So many things to fix you lose track!! Vacuum !!!!! I got it.

Another place to check is the passenger side strut tower where the vaccum lines go to two senders and then to the plastic vaccum tank. I've had a split in this area that has caused this problem on my 1977 280Z.

My problem in the vac lines for heat were disconnected in the engine compartment when I got the car. I tried to follow the diagrams but am not been able to follow them. I have tried a few different configurations I thought looked right but nothing. There were no lines to the senders so I am basically winging it Any other suggestions. Anyone have pics??