heater (or lack thereof)

[astewart]

Ok. Well, I fixed that vacuum line, but it didn't fix the problem. In fact, I didn't notice any change at all. But! Now to just replace all those lines and then I will KNOW everything is complete.

I went to that website that Friar-Tuck gave me and I AM IN Z CAR HEAVEN! There is so much stuff on there that I have been trying to find the information for! Thank you so much for giving me that address!

And thank you too, Jeff, for giving me such detailed possibilities!

You guys are awesome and I really appreciate all your help so far!

[Jeff G 78]

There is one quick test you can perform, but I can't remember off-hand where it is on a '78. The diverter flap in the heater box is controlled by a vacuum diaphram under the dash. When the diaphram gets vacuum, it closes and moves the lever that shuts the flap in the heater box and diverts air to the heater core. On my old '76, the diaphram was under the driver's side of the dash. I could actually reach it while driving to close the flap (I had a cracked hose and wasn't getting heat). If you reach with your right hand while seated in the driver's seat WAY up under the dash, you can fish around and feel that there is a canister with a lever on the bottom. If you push that lever up, it will simulate vacuum and close the flapper in the heater box - giving you heat. On my '76, once I pushed it up, it would stay there until I pulled it back down. If you follow the cables from the heater box, you should be able to find the vacuum diaphram. It will have a vac hose going to the top and a lever and cable going to the bottom. Again, this is from memory of the '76 I had 25 years ago . I don't know for sure where it is located on a '78. If I get a chance, I will look at my '78 tonight and let you know.

While checking the vacuum lines, be sure to check the rubber fittings on the RH side of the engine bay where the vacuum hoses connect to the vacuum solenoids near the fusible links (look for the once white square plastic domes that are now probably cracked and discolored). Those fittings can crack as well as the hoses.

Good luck.

[BOMBAYBOB]

Hy guys, First time on the site. 78z Same issues. air only from the front vents. No heat. The vac hose that leaves the interior and goes into the engine compartment has been cut at the firewall (in the engine area) Anyone know where it should lead?? I have a round whiteish clear plastic tank about the size of a soda bottle on the pass side on the engine area above the starter. could it go there? what the hell is it.

[Jeff G 78]

The whiteish bottle is the vacuum reservoir. The vac hose that starts at the firewall does go that direction, but it might(I'm not near my Z right now) go to the solenoid rather than the bottle itself. The solenoid is right near the bottle in the metal box. I can look at mine tomorrow and let you know exactly what the routing is supposed to be if you don't have an answer before then.

Edited November 26, 2008 by Jeff G 78

[sblake01]

This is from the 78 FSM:

[BOMBAYBOB]

AH HAA!! Big help. Let me get to work and I will let you guys know what I find

Thanks

[astewart]

By the way, Jeff, I haven't been back on here since your last post to me but I just had to send a HUGE thank you!!! to you for helping me so much in fixing my heat. That vacuum canister under my dash completely did the trick! But I got to thinking and is there any way to fix that canister so that it works properly or will I just need to order a whole new part?

[Jeff G 78]

So Alicia, did you mean it was the vacuum diaphram? You said vacuum canister and I got confused. If the diaphram is getting vacuum (no cracked hoses and proper vacuum from the engine) but not pulling in, then you are going to have to replace the part. I have never seen one go bad, so if it truely is bad, you should be able to get a used one. There are always lots of Z cars being parted out so it shouldn't be hard to find.

How did you diagnose it? If you simply pushed up on the plunger and got heat, then I'd say the problem is still with your vacuum hoses or maybe a cracked fitting on the vacuum reservoir. To check this, remove the vacuum hose from the diaphram and install a three foot length of hose to it. With the engine running and the car warm, suck on the end of the hose and see if the diaphram pulls in. If it does, you should get heat from the floor vents. If not, the diaphram is dead. Do this check before you replace any parts (other than ALL the hoses, which need to be replaced anyway). Let me know what you find.

Good luck.

[astewart]

I will let you know for sure. Hopefully I will be able to get to that this weekend, since it's kind of a 'work on my car' weekend. hehe (this weekend means sun, mon, tues for me)