Replacing heater parts - what do I need?

[smh00n 94]

My 70 with factory a/c seems to have destroyed the heater core, so I pulled the hoses off. Now I am in need of a heater soon and want to replace the parts.

I know I need a core but what other hardware on the Engine side do I need? I’m currently on vacation in the USA so don’t have access to my parts books.

[Ridge Runner 1,238]

You will need a complete seal kit for the box 

[aslanefe 356]

Heater hoses go from the heater core to engine. So, on the engine side all you would need are hoses and clamps; if your vacuum activated cut off valve is not working, then a new valve. The hose from heater core to valve is an S shaped hose you have to get from a Mustang parts vendor; other hoses are cut to length hoses you can get from any parts store.

[smh00n 94]

Thanks guys. That’s what I figured I needed. Does the valve brand matter? CJ have a different one to West Coast Cougar (who I think are probs the better source for OEM stuff) but WCC are out of stock of the seal kits. And is it just supported by the hoses and not attached to anything?
The vacuum hoses probably all need replacing as well. Who does them?

[Mach1 Driver 639]

here is a link to the gasket set: https://www.npdlink.com/product/gasket-set-heater-box/103212?backurl=search%2Fproducts%3Fsearch_terms%3Dheater%2Bdoor%2Bfoam%26top_parent%3D200001%26year%3D1969&year=1969

[aslanefe 356]

On 6/4/2024 at 2:47 AM, smh00n said:

Thanks guys. That’s what I figured I needed. Does the valve brand matter? CJ have a different one to West Coast Cougar (who I think are probs the better source for OEM stuff) but WCC are out of stock of the seal kits. And is it just supported by the hoses and not attached to anything?
The vacuum hoses probably all need replacing as well. Who does them?

As far as I know, the valve is supported by the hoses; no hard attachments. Brand shouldn't matter if inlet and outlet diameters match to the hose; all it does is close the hot coolant to heater core when AC is on.

[smh00n 94]

Dragging this back up; this is a factory a/c car but I am not replacing/fixing the a/c as we live in a cool climate.

do I need to replace all the vacuum hoses under the dash to just have heat from the cooling system? Or are all the hoses I see for the a/c side of things? We’ve just moved house so all my books are in a box somewhere.

I've ordered the heater core from summit and need the heater box seals and everything else to warm me up. 
It looks like all the heater stuff is there, just old and tired. The cables seem to work although very stiff (I assume cables operate the blend door and vents?)

[det0326 207]

I would replace all the vacuum hoses, even the the main supply going out to the engine and make sure all the selections are working as they should. That's just me tho, you never know what may happen in the future. I would also pressure test the evaporator for leaks then purge the air out with some CO2 and seal it. That way everything for the A/C under the dash would be complete and if you ever want to finish it, stuff in the engine bay is not hard to get to.  I realize you are in Australia and parts  probably cost more because of shipping and all but it will be worth it in the end. 

[aslanefe 356]

On 4/8/2025 at 8:19 PM, smh00n said:

Dragging this back up; this is a factory a/c car but I am not replacing/fixing the a/c as we live in a cool climate.

do I need to replace all the vacuum hoses under the dash to just have heat from the cooling system? Or are all the hoses I see for the a/c side of things? We’ve just moved house so all my books are in a box somewhere.

I've ordered the heater core from summit and need the heater box seals and everything else to warm me up. 
It looks like all the heater stuff is there, just old and tired. The cables seem to work although very stiff (I assume cables operate the blend door and vents?)

On A/C car heating system, the blend/direction doors are vacuum actuated, so you need to check/replace the vacuum hoses (and the vacuum canister) if you want the ability to direct the hot (or cold) air to where you want (floor, dash etc) even if A/C is not operative.

[smh00n 94]

Do you know how to source the hoses? If they are just a 1/8” rubber I can probably get them here.

I’ll test the vacuum can for vacuum, if it is NFG are there kits or I just chuck any old one on?

if there is a manifold under the dash chances are it is busted as well so clues on getting that?

[Mach1 Driver 639]

The kits for 69s appear to be discontinued. They had lots of hoses, one T and one thru-plug- take a look at the pictures here: https://secure.cougarpartscatalog.com/17434/31522/vacuum-line-hose-kit-air-conditioner-repro-1969-1973-mercury-cougar-/-1969-1973-ford-mustang.html

There is lots of conflicting information about the hose size, but it may be 5/32" internal diameter.

[smh00n 94]

1 hour ago, Mach1 Driver said:

The kits for 69s appear to be discontinued. They had lots of hoses, one T and one thru-plug- take a look at the pictures here: https://secure.cougarpartscatalog.com/17434/31522/vacuum-line-hose-kit-air-conditioner-repro-1969-1973-mercury-cougar-/-1969-1973-ford-mustang.html

There is lots of conflicting information about the hose size, but it may be 5/32" internal diameter.

That’s really helpful. It has the routing and the colours which are easy to read. 
NPD have this set https://www.npdlink.com/product/air-conditioning-vacuum-hose-set/103380 but not listed for our years.