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replacing hvac system, 1976 280z


280zex

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so once again my heater core went bad. the replacement unit only lasted 6 months before bursting at the seam. I have decided to pull the entire system and getting a 1 piece unit from jegs. I have no need for air conditioning, so my thought is to replumb the dash vents to have heat in the winter!!

 

there are several holes in the fire wall and trans tunnel that I will need to plug, and the big hole for out side air access for the original hvac.

 

what about fresh air access for the new heater core unit you ask?? well there is the floor board fresh air access ports to the wheel wells that I can re-direct to the blower unit. this will allow me to have full heated/non heated air flow to the cabin, depending on what I want.

 

the first pic is the stock hvac unit, the second pic is the jegs unit. I tried to paste a link to jegs , but my net book is not working correctly after an update, sorry ;-(

 

 

 

 

 

 

 

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  • 2 weeks later...

Ok I got all the new mounts fabricated and the coolant plumbing done! The eletrical connectons were a snap, and thats always nice :-) all I need now is some 3 inch flex hose and a pair of 3 way couplers to reroute the forced air to the defrosters and the dash vents. Im going to stop by lowes tomorow for some pvc parts and flex hose.

 

I decided to get AN fittings and bulkhead mounts for a clean and easy coolant line install. I also had to relocate the fuel rail cooling fan control thermocouple to the t-stat housing. I just need to shorten the wiring and wrap that for a clean, and trouble free wiring setup for the fan control unit.

 

The blower unit comes with a 3 speed switch and its own wire harness, so plug and play!! I do not have a coolant line shut off to the heater core as I dont run the t-stat bypass hose.

 

The blower fan that comes with the new heater core unit flows some serious air and is nice and quiet!!

 

Also I saved 11 lbs of weight going to this new compact unit vs the stock hvac. I would recomend this for those who do not have the original hvac unit, or if you want to shave some weight and still have cabin heat. You will need some good fabrication skills to do this swap, its not as easy as i had originaly thought.

 

Total time for the install was 8 hours. I did not have to drill any holes and was able to scavenge some of the original hvac brackets for mounting. The new unit does come with its own mounting hardware, but i found it much easier to use some of the factory brackets.

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Edited by 280zex
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Looks nice. What did you use for the inside bulkhead to heater core connections?

 

When you remove everything, do you have to deal with the cowl air intake? Does it leave a hole to seal up?

 

Again, nice job... I think this is in my future :)

I used the same type AN fittings and nylon braded hose from the bulkhead to the heater core. its over kill i know but I should never again have to deal with leaky hoses!! That also makes for easy removal if i have issues.

 

Yes there is a big hole in the bulk head for the original hvac fresh air. I used some 18guage aluminum scrap to block that off and sealed it with rtv silicon. If that does not hold i will try some JB weld. There is also the a/c water drain hole in the trans tunnel i had to fill with a rubber plug.

 

I found that the new fan flows so much air volume that I gota figure out how to choke back the dash pull vent. Its a bit much!! I may try some air filter material stuffed down the dash vent hose.

 

The bump in the glove box made routing the passenger side dash hose a chore, but I got r done!!!

Edited by 280zex
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Any updates?Just curious :icon10:

The new system works great, good heat thru the dash vents and defrost at the same time!! However there is that new plastic type smell from the new heater core box that is going to take time to go away. Its rather stinky so I picked up a febreeze unit for automoive use. I do hope at some point that smell will go away.

 

I would recomend this system for some body that doesnt currnetly have a heater core unit and wants good reliable heat in the cabin. Its a good price and requires a small amount of fabrication for what you get. It does get a bit tricky routing the hose connections for the passenger side dash vent due to the shape of the glove box. It is easy enough to go get heat riser hose for extra plumbing of the air as seen in another post here in the interior section.

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I've been running the exact same unit in my car for about 4 years now...  Works great as a defrost heater (but mine never had a smell to it, even when new). 

 

I was thinking about modifying to save extra weight by removing the large fan and replacing it with a high power cooling fan like those used in desktop computers.  It may not flow as much air but I only need it for defrost anyway...

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ya know they do make miniature ducted type cooling fans for pc's. I would think you may possibly be able to slip one right inside your hose going to the defroster itself??? I measured the unit I have on my pc and its only 2 inch OD!! Its called the volcano vortex. It is several years old but maybe google can help ya find one :wink:

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