heater (or lack thereof)

[astewart]

For as long as I have had my car (over a year) there has never been any kind of warm air to come out of the vents. You turn on the heater/AC blower and it blows whatever air temp it is outside. After the car has been running for an eternity, the air coming out of the vents will turn about as warm as a summer breeze (not even close to warm). This being the case, I don't actually know what is preventing it from working correctly. The AC works great in the summer. Anyway, I have ruled some things out. First, I don't think it's the heater core. No liquid has ever spattered onto my windshield or onto the floor. The hoses running from the radiator to my heater core are both warm, which tells me that the water is cycling the way it should. Like I've already said, the blower motor works fine. I also don't think it's my thermostat because my car warms up in the usual 10-15 minutes. What is THINK it is, is that relay/rheostat(heater valve?!?!?) underneath the heater that connects directly to the heat control lever in the console.

Now, 3 questions: (1)Am I right in thinking that that is what's wrong with the heater, (2)Is it replaceable, and (3)Can I do it myself without giving myself anxiety attack from stress and being forced into gymnastics? :laugh:

It is a '78 280z

Edited October 22, 2008 by astewart

[MikeW]

I can't be too specific about a 280Z but there's always a valve that controls whether hot coolant flows through the heater core. I recall that people here have mentioned that the 280Z uses vacuum to control components instead of a simple cable but I don't know if that applies to the valve itself or just the air flow controls. I doubt there is anything electrical involved (relay or rheostat).

[astewart]

The part I am talking about is about an 1-1 1/2" cube that has a what appears to be a vacuum hose leading all the way up into the heater core on one side, 2 electric connectors coming out of another side. It is also connected to a bar that is directly connected to the heater control in the console. I'll get a picture on here soon of what I am referring to.

[beandip]

It would likely be good to let us know what year this Z is. I am not one to offer info on 280s but I do know that there are differences from year to year.

Gary

[astewart]

Picture looking behind the heater console plate. You can see the part I am talking about that is orange and also circled:

Here is a picture closer up and looking up at an angle at it. You can see the electric connectors I was talking about and a glimpse of the metal hose (vacuum?) coming out of the side of it. It's metal the entire way into the heater core. You can actually see more of it in the above picture. It looks like it would lead directly into the top of the orange part, but acually curves into the side of it.

Let me know if this is helpful or if anyone wants more pictures that may be more specific. Thanks

[astewart]

It would likely be good to let us know what year this Z is. I am not one to offer info on 280s but I do know that there are differences from year to year.

Gary

It is a '78 280z

Sorry about any confusion.

[Jeff G 78]

When the control lever is set to floor, does the air come out of the floor vents or only out the center vent?

You cannot get heat from a Z unless the air comes out of either the floor, or defroster vents. The center and side vents are only for either unheated outside air, or A/C.

If you have it set to floor and only get air out of the center vents, then the problem is with the vacuum system - most likely a cracked vacuum hose.

If you get cold air from the floor vents and defroster vents, the problem might be the heater valve. If you look at the firewall behind the engine, the two heater hoses go through the firewall and directly into the heater valve. If the cable is broken or way out of adjustment, the valve might be staying closed. Look under the dash and find the valve (it's not easy to see and you might have to remove the glovebox). When you can see it, move the temp lever back and forth to see if the valve opens and closes. If it does, then you might have a clogged heater core. This is unlikely, however. Do the tests in order and let us know what you find.

[sblake01]

The switch and the capillary tube (metal vacuum hose as you put it) are for your AC and have nothing to do with the heater. The tube actually goes between the fins of your AC evaporator to sense the temperature and cycle the compressor on an off the keep the evaporator from freezing. There might be something in this thread that will be of help.

[Friar-Tuck]

Here's a link to xenons site for FSM download.

(I hope)

http://www.xenons30.com/reference.html

to go along with Mr. S.Blake01's post above.

Tuck\o/

[mikehos2004]

Astewart,

I had the exact same problem you describe with my 78 Z. AC worked great, and the blower came on when I tried the heater, but no heat. Maybe someone already hit on this, but there was a thread a few months ago saying the most common reason for this is a cracked vaccum tube. I know very little about fixing car problems (just love driving the car) but I went out and tracked all those little tubes and sure enough found one that was cracked! Snipped off the end, stuck it back in, and the heater worked. It was great. So if you haven't already, go check all those little black tubes (black on my car, at least) and see if that gets you anywhere.

And your right, this site is the best!

Mike

[astewart]

Ok, I can already tell you that I only EVER get air coming out of the middle vent. No matter what setting it is on, I've never had air come out of the defroster vents and honestly just figured that here were no floor vents because I have never felt air coming from there either except for the outside air vent.

Second, I actually found a vacuum hose that was disconnected, but don't know if it is related to this or not. I noticed it this summer, so I connected it again, later turned on the A/C and the RPMs shot up to about 6000 and stayed there, no matter if I was moving or parked. So, I disconnected it again. I will check this again here in a minute and see if I can't see any other cracked or disconnected hoses.

Is there any specific place I should be looking for this hose or is it different every time?

Edited October 23, 2008 by astewart

[Jeff G 78]

Due to the age of your Z, you should buy about 15 feet of vacuum hose and replace every vac hose under the hood. I found that they crack most often on the RH side of the engine bay between the vacuum solendoids and the firewall, but they can and will split everywhere.

With the info you have given, you have found the problem and now just need to replace the hoses.