Heater Core

by jrb75 Fri Nov 04, 2011 4:51 pm

I have to replace it in the 75, gonna shoot for this weekend. I've never done one before and I know its a pain. Advise or suggestions?

by Limey SE Fri Nov 04, 2011 5:31 pm

yes I HAVE ONE bring the car to limey I will fix and take it to Tennessee with me and your worries will be over. LOL

by jrb75 Fri Nov 04, 2011 6:10 pm

NO, bad Limey!

by ant7377 Fri Nov 04, 2011 7:35 pm

Its a pain take your time .You can break stuff under there remember to disconnect the cable.

by 77mali Fri Nov 04, 2011 7:56 pm

When I did mine I had the wheel well off & as a result the battery tray should be removed too. Then you can have easier access with the car safely lifted/supported w/ the wheel off. My $0.02. On the interior side all my stuff was stripped out including the dash so you may have a bit of a struggle in there. You may want to buy a Haynes manual as it explains it in the one I have for Malibu. They're about $20.00 & well worth it. The cable is under the A/C and has a small retainer similar to the ones in the dome light housing. Also LABEL ALL YOUR CONNECTIONS and such as you will be unscrewing/unbolting a bunch of stuff when removing the housing. Be careful & take your time. You should be prepared for about a 6-8 hours for this job. Other than that, no big deal. LOL. Oh...and have both your wrenches & sockets handy.

heater core - Heater Core Dsc01522

by pila Fri Nov 04, 2011 8:56 pm

I've done quite a few including our generation cars. The worst one I ever did was my youngest son's 1980 Sunbird. Had to remove the whole dash to get the heater housing out.

by Limey SE Fri Nov 04, 2011 9:55 pm

jrb75 wrote:NO, bad Limey!

Well it was worth a try right

by Mcarlo77 Fri Nov 04, 2011 11:00 pm

Isn't there a bolt at about the 5 or 6 o'clock position on the engine side of the heater box (below the blower) that is virtually impossible to get at without removing the inner fender liner?

by Limey SE Sat Nov 05, 2011 12:15 am

Mcarlo77 wrote:Isn't there a bolt at about the 5 or 6 o'clock position on the engine side of the heater box (below the blower) that is virtually impossible to get at without removing the inner fender liner?

HELL YES THERE IS AND IT SUCKS TO GET AT

by 1973 454 MONTE Sat Nov 05, 2011 11:09 am

i need to do mine in the monte. im gonna do it when i take the interior and the motor out.

OR sell it first and let the next guy do it scratch

i really need to get the caprice running,hate that it is just sitting.if i get my garage than i might just put the monte in the corner and wait till my youngest turns 16 and let him tinker with it.

by jrb75 Sat Nov 05, 2011 2:07 pm

Thanks for the advise guys....and thanks for telling me how much it's gonna suck,lol. After the freeze plugs disaster, I had a feeling the heater core would have rotted out too. 6-8 hour job for me means 2 days. Ehh, I'll take in account all you guys said and it'll be alright....Thanks again all.

by jrb75 Sun Dec 11, 2011 4:53 pm

AHHHHHHHHHHHHHHHHH, I finally got it the core assembly and some of dash back together and I heater controls are shot. Before the heater core, I knew my fan wasnt working but turns out, I had a blown fuse AND a box on the back of the unit was destroyed.

Since I have to use words like thinky and what-cha-ma-call-it...The temp and postions controls go into it. After 6 times of figuring out how to get it together, I superglued the box and found a spring that was supposed to be in it on the floorboard after I got it all back in the car...

Do I start with just replacing the entire control unit?

by pila Sun Dec 11, 2011 9:24 pm

Finding another dash control unit may be your best bet. I sold one last year. Folks parting out gen 3 stuff may have what you need. They are not all the same from '73 to '77, so pick your year when looking for one, and good luck....
BILL

by 77mali Sun Dec 11, 2011 10:14 pm

What box on the back got destroyed? Can you post a pic? Pila has the right idea, the whole control unit would be the best bet. They are usually only between $20 to $50 depending on the condition for a good used one.

by Mcarlo77 Sun Dec 11, 2011 10:59 pm

Jrb...contact me and I'll find one for you. Might even have one laying around. Need to know if you have A/C, though.

by jrb75 Sun Dec 11, 2011 11:14 pm

77mali wrote:What box on the back got destroyed? Can you post a pic? Pila has the right idea, the whole control unit would be the best bet. They are usually only between $20 to $50 depending on the condition for a good used one.

I'll try to do that tomorrow, wife roped me into Christmas lights this afternoon so I hadn't gotten anywhere with it. Sent a PM off to Mcarlo77 too for another unit.

by 77mali Mon Dec 12, 2011 1:13 am

Christmas lights take precedence...I have not touched my car in 3 weeks w/ all the to do stuff for Xmas. Oh well I'll have from the 26th through the 1st. Very Happy

by jrb75 Tue Dec 20, 2011 9:48 pm

Houston, we have heat....Stephen, you kick A$$ brother. The blower works and I get air through the core. I haven't figured out the defrost yet???? No air out those vents when I go to def but, I haven't put all the plumbing back in yet...Anything I check BEFORE Iput it all back in?

by pila Wed Dec 21, 2011 2:10 am

There is the vacuum selector behind the control, and when selecting defrost, it puts vacuum on the diaphragm/canister that moves the defrost door in the heater box. The colors on the hoses that run to the defrost canister are light blue/black, and dark blue/black, from the selector valve.

If you have AC, the colors are different, with a red, and a blue hose running to he canister.

On some cars, the hose colors may have one that is different also, as I discovered....

by jrb75 Wed Dec 21, 2011 12:43 pm

Thanks pila, I'll check it tonight.

by jrb75 Thu Dec 29, 2011 4:31 pm

Ok, basically I have no vacuum, none of the doors open when I engage the lever...One line going to the reservoir is trash (bigger one), I rigged it but have no faith in it and a third-shorter line coming out of the firewall has the rubber connector torn up. No idea where that one is supposed to go and it is not color coated. The closest diagram I found was from a Corvette site.

Where does that 3rd line go? I don't see a line going from the system to the intake for vacuum so, that may be it. It was a mess when I got it and I made it a bigger mess when I put the motor back in after a partial rebuild...lol

by Mcarlo77 Thu Dec 29, 2011 8:20 pm

Darn...wish I would have thought to take some pics for you yesterday while I was pulling the wiring out of a '75 Laguna at a distant yard. You should have a "tee" in the middle of the run from the firewall to the reservoir that allows a hose to the intake vacuum source. Maybe I can find the necessary parts on the '76 Laguna sitting at the local U PUll tomorrow.

by ant7377 Thu Dec 29, 2011 9:20 pm

Do you have the hose connected to the vacuum ball on the right side wheel well near the AC box? Thats where all the vacuum for the system come from.

by jrb75 Fri Dec 30, 2011 11:25 am

ant7377 wrote:Do you have the hose connected to the vacuum ball on the right side wheel well near the AC box? Thats where all the vacuum for the system come from.

Ant, I do have those in. One is trash but, rigged so it should hold enough. I thought that was a reservoir and the system needed vacuum from the intake? I'm gonna try to get replacements in the meantime. If that 3rd line was part of a "T", where would that 3rd leg go ? 1 out of the firewall, 1 to the intake and the 3rd to?

Boy, I tell ya's...I appreciate the help but, never thought I'd be gettin this deep into heating system...lol...The things we do for our cars. That might make an interesting topic on its own.

by 77mali Fri Dec 30, 2011 1:49 pm

Are all your lines connected from the heater/ac control unit to the connection from the firewall (matching receptacle)? Make sure the lines (colors) match there. If there are any breaks, you can get some plastic splices from the auto parts store or just some new lines if they have them. If you have a VIP auto parts near you I think they sell rolls of diff diameter lines.
I'm thinking also that the third line you're referencing might splice into a Tee splice that goes from the distributors vacuum advance line which then connects to the carb but my memory is fuzzy there...I seem to remember that this is where the vac line connects into the vacuum ball, in the engine bay & sounds like you're doors are not opening because the vac from the engine isn't making its way in to the system.

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