Installing a New Heater Core for a 1978 280Z

Ok, so like me you put off installing that heater core.  You figure you can bundle up in winter and besides if you are like me you try not to drive your Z to much in the winter anyway.  The problem is “YOU LOVE TO DRIVE YOUR CAR!”.  Ok Not every day is wet and wintry.  There are plenty of days in the winter you can drive your car.  But it sure would be better if you could be nice and warm while driving your car.  Did you know  that these old Z’s put out really good heat?  We’ll they do!  And I bet you figured it was a really big job.  It’s not too bad at all.  At least not for the 1978 280Z.  I would imagine that the 70 through 77 are about the same.  If you have a 280ZX, it is a little more difficult, because you have to remove the dashboard – not so with the 280Z.  Ok let’s get started.

Tip 1:  Take pictures with a digital camera as you go, so you know where to put things back.  If you need too, write down any special notes.  You can also use tape to tag or label things.  “1 to 1, 2 to 2, etc…”or Colored tape works too.  “red to red, blue to blue, etc…”

Tip 2:  As you take things apart, have a place to separate things and label them.  (A) Screws to heater panel that sits over the heater controls (B) Screws to glove box, etc…

Note:  I am not a mechanic and basically that means the wording I used is in layman's terms.  Hope it helps you!

Instructions Click on Picture to enlarge

1) Remove your center console.  There are just 2 bolts “one on each side” holding it on.  So this parts easy.  Just be carefull not to tear your boot shifter when pulling it out.  What I recommend is that you remove the 2 bolts, untie the boot shifter, and then carefully lift it so you can unhook the electrical connectors.  You might want to tag or label what each one is, but Nissan was nice and each connector is different, so when you put it back together you won’t have to guess what goes where.


2) Remove your radio.  Usually just unhook the antenna, 2 power wires and speaker wires, depending on your radio “stock or new”.



3) Remove the panel that is on top of the heater control switch that is above the radio.  Just 4 screws.  Note when you put these back, make sure you don’t over tighten and break the plastic panel.


4) Next remove the plastic panel that goes below the glove box.  Just 2 screws.  Slide the panel up and out.



5) Remove the glove box door and glove box.  There are several screws here at top and bottom.  You’ll have to remove the glove box light too.  First remove the door.  You’ll have to angle it out to get the curved arm out.  Once the door is out, unhook the light.  Get all the screws out from inside the glove box and the carefully slide it out.  Mine was really tight and I kind of pinched it down as I pulled it out so that I did not scratch or tear my dashboard.  It had a tendency to catch as I pulled it out.  Once you have the glove box out, then you can see everything:  (Blower Fan) – (Heater Control Valve) – (Door or cover to the Heater Core).


6) Now you can remove the Blower Fan and Fan Housing.  It’s directly behind the glove box.  You’ll unhook or pull out the electrical plug.   When you get it out, you’ll want to clean it up and put new rubber where the vent connects to the vents that are under the dash.  I went to the hardware store and purchased 2 sided rubber tape.

Tip: There are also small rubber heater vacuum hoses.  Label them and take pictures so you know where they go.  If you don’t get them hooked back up properly, then you heater won’t work.


7) Next you’ll need to carefully remove the rods that go from the heater control valve up to the heater control switches up where you turn your heater on and set the temperature level.  Unhook those wire “rods”.

Tip:  Be very very careful not to bend or break the small thermostat wire.


8) You will need to undo or loosen the water hoses that go from the heater control valve to the heater core.  Then you’ll need to disconnect the heater control valve from the firewall.  Pull it out and take the old hoses off.  Clean it up real good and put the new hoses on.  This is probably the hardest part, because it’s hard fit to your hands down there.  Also note those vacuum hoses.  They just pull off, but you need to know where to put them back.


9) Now the last thing to take out is the heater core itself.  This is the easiest part.  There is just a black panel or door.  You just remove the screws and slide out the heater core.


10) Clean up everything.  Get any crude off.  Use a scraper and compressed air helps too.


Now it’s time to put everything back together.  Basically you do everything in reverse.

1) Slide the new heater core in and put the heater core panel back on.


2) Put the new hoses on the Heater Control Valve and attach it to the firewall.


3) Attach the Hoses from the Heater Control Valve to the Heater Core.


4) Attach the cables running from the heater switch “Control Panel at the dash” back on to the Heater Control Valve.



5) Attach the Vacuum hose to the Heater Control Valve.



6) Put the Heater Blower Fan back in its casing and attach it back underneath the dash board.  Plug in the wiring to it and plug and attach the remaining vacuum hose.


7) Next make sure all the tubing to all the heater vents is hooked up securely.  I used 2 sided tape to make sure all the vents would not leak air and I also used plastic ties to secure them down.



8) Next go to the engine bay and attach the water hoses that connect to the piping for the Heater Control Valve.


9) Next test the heater to make sure it works before you put the glove box and radio back in.  Look for leaks and make sure you are getting heat.  If all the vacuum hoses are not connected, it will not work.  Once your satisfied, you can put your glove box back in and attach the glove box door.  Put your radio back.  Put your center console back in and hook up all the wiring there.  You’re good to go.  You probably will want to drive the car and do a good test to make sure there are no leaks.  Check it for a couple of days just incase.  You might even want to leave the glove box out for a day or so just incase you need to get in there and do some tightening.  The hardest part is getting your hands on the hoses on the heater control valve to tighten them up and to tighten the screws that attach the heater control valve to the firewall.  There’s just not that much space there.



When we did the job it took most of a Saturday.  It was a learning experience.  But honesly if I had to do it again, I think it would be a ½ day job at the most.

Here's a link to all my pictures and they are not in any order.

Here are some alternate steps I found on the internet.

Heater core repair,
Remove center console, then remove glovebox door, light and interior 
latching mechanism. Then remove inner box of glove box.
Disconnect blower motor electrical connection.
Remove three screws holding blower motor to housing.
Remove blower motor.
Remove door actuator cable.
Remove bolts securing blower housing to firewall.
Don't forget the screw that secures the blower motor housing to the 
heater housing.
Remove inner door actuator cable.
The heater core is located at the bottom of the heater housing that can 
now be seen clearly.
Disconnect the heater hoses from inside the engine compartment.
Have a bucket ready to catch any coolant that will escape.
Now move back to the interior of the car. Also have a towel ready to 
catch any coolant that may leak out during the following.
Remove heater hoses that connect the heater core to the heater water 
This can be difficult, as the clamps are not always turned to where 
they can be reached easily.
Remain determined, and remove all flexible hoses that connect the 
heater core, heater water valve, and the metal connector that goes through 
the firewall to the engine compartment.
Once the flexible hoses are removed, remove the two screws that secure 
the heater valve to the heater housing.
Remove heater control valve.
Remove the screw that secures the interior to exterior hose connector.
On the passenger side of the heat housing there is a small door that 
opens to direct air to the floorboards.
Adjust the heater controls until you see this door open.
Once the door is open you can remove the wire arm that controls the 
small door.
Once this "arm" is removed, remove the screws that secure the passenger 
side panel from the heater housing.
Remove the cap and you can then slide out the heater core from the 
heater housing.
Once the heater core is removed clean out the heater housing where the 
heater core was located.
You can now reverse this process to reinstall a new heater core.
The new heater core should have some foam strips attached to it, this 
makes the reinstall a little difficult but go slow and easy. Also use 
caution when sliding in the new heater core so it is not damaged by the 
interior workings that are located within the heater housing.
This is a VERY good time to replace all of the flexible hoses you have 
removed, as well as the water control valve, and the interior to 
exterior hose connector.
This is what I did to replace the heater works on my 1975 Z coupe with 
A/C. Nissan is currently still stocking the necessary parts at the 
following prices.
Water control valve $60
Interior exterior connector $16
I got my heater core off of ebay and paid around $50.
To think I traded in a 280Z once because it needed a new heater core 
and I thought it was a difficult job!