08-22-2022 | #21 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
After spending the evening in my shop manual I finally found the relevant section under General Engine Mechanical. More on-car research tonight!
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ZR-1 #638/1991 |
08-22-2022 | #22 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
So, I checked the vacuum system. I pulled 15 in hg from the canister/secondary air valve/cruise control branch. Absolutely no issues here.
Next I pulled vacuum directly at the plenum connector into the HVAC branch. Also super tight, no issues. Also the check valve seems to be fully operational. So... I can't spot any unexpected behavior along with the HVAC vacuum circuit. I will try to pull the modulator tomorrow and check for a potentially defect valve. But I doubt that this is the source of the noise I mentioned earlier. Also the new heater core arrived today. Big day tomorrow...
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ZR-1 #638/1991 |
08-23-2022 | #23 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
So, while I was in there... I decided to take the chance and fix my CDM holder. Both tabs were broken. Inspired by one of our brothers who did a similar job (just don't remember who...) I shaped two new tabs from a strip of aluminum and used pop rivets to attach them to the carrier.
Also I reinforced the rivets with washers to avoid that the brittle plastic breaks again. I added some more washers to the cruise control module screws to gain clearance and compensate the rivets heads. Built to last! 20220823_144552.jpg20220823_151100.jpg20220823_151109.jpg20220823_151622.jpg
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ZR-1 #638/1991 |
08-23-2022 | #24 | |
Join Date: Apr 2007
Location: Lake Bluff, IL
Posts: 2,035
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Re: Heater core recommendation needed + another HVAC issue
Quote:
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2016 Long Beach Red Z06 #10281 "POPS Z" 1995 Polo Green #409 "WARP TEN"--Haibeck 350/510 package, 4.10s, Hurst, Stock Exhaust with QTP Cutouts --Sold but still running strong 1993 Quasar Blue #161 "HIL KING" --Sold but still running strong, now with more than 120,000 miles 1967 Marlboro Maroon/Saddle Corvette Coupe 300 hp/4-spd --Sold a long time ago ZR-1 Net Registry Founding Member #95 NCM Lifetime Member Favorite Quote--Attributed to Mickey Thompson: "Too Much Horsepower is Almost Enough" |
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08-23-2022 | #25 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
Thanks, Bob!
However, now I'm stuck and need advise. I removed everything to gain access to the core. But at the end the shop manual isn't very precise... My understanding is that I don't remove the entire heater core housing but only the rear cover. Is that correct? If so, there are 2 things in my way which I can't remove/separate. First is the hose that feeds the passenger door defrost. I removed the 2 screws that attach it to the heater core cover. But I don't see how I remove the hose. Do I just have to pull it towards the passenger door? Second, there is a kind of cylindrical shape riveted to the heater core rear cover. Towards the passenger it connects to the interior temperature sensor hose. Towards the engine it connects to another hose that disappears behind the temperature control motor. There is little to no room to grab those hoses where they connect and separate them. I tried to take a picture but it'll be hard to tell from that one... Long story short: how do I finally remove the core when everything else has been taken out?20220823_183343.jpg20220823_183403.jpg
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ZR-1 #638/1991 |
08-23-2022 | #26 |
Join Date: Aug 2006
Location: McLean, VA
Posts: 3,703
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Re: Heater core recommendation needed + another HVAC issue
Matt,
it has been a while since I did this work. And, secondly, I don't have very good memory. What I do recall is fighting to get some pieces out and in some case, locating and removing 7mm hex purely by feeling it with my fingertips. Also, I believe you are right that you need to remove the housing cover and not the entire housing. I just kept removing pieces until I can pull and remove the heater core. |
08-23-2022 | #27 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
Thanks, Yun. Sounds exactly like what I did - work on until there's nothing left to remove!
I found and removed all 7mm hex keys and can actually easily MOVE the cover. But I can't REMOVE it. Maybe I need to apply more brute force to get the clearance I need. But I don't want to break anything that requires the whole center console and lower dash to be removed in order to fix it...
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ZR-1 #638/1991 |
08-23-2022 | #28 | |
Join Date: Aug 2006
Location: McLean, VA
Posts: 3,703
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Re: Heater core recommendation needed + another HVAC issue
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08-24-2022 | #29 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
Hahaha, oh my God... That doesn't sound very promising.
But you may be right. It seems that EVERYTHING is in the way here...
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ZR-1 #638/1991 |
08-24-2022 | #30 |
Join Date: Jan 2021
Location: Beautiful Bavaria
Posts: 517
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Re: Heater core recommendation needed + another HVAC issue
Finally!!! Not sure who designed this, but... SHAME!!! [emoji1787]
Seriously, this is a really nasty piece of work. If another brother has to go down that road I STRONGLY recommend to pull the dash, etc. It causes additional work but pays off easily the further you dig in. I again studied the shop manual and realized that the horizontal tube runs all the way through the lower dash into the drivers footwell. There is another screw hidden behind the main wiring harness. With that screw removed the tube first has to be pulled away from the rear heater core cover for about 2 to 3 inches to clear the connector between the two and then towards the passenger door. What a tricky surprise at the end of the disassembly story... Now everything is set and ready for reassembly. 20220824_183402.jpg
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ZR-1 #638/1991 |
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