Bob2.0

On my 94 coupe, I am in the process of replacing the heater core. I'm using the FSM to do it and recording the process so that I can post it when I'm done. There's already a video online from JC316 doing this in a 92 but for those of us with the passenger side air bag who can't get out of removing the dash pad, I figured a new video might be useful.
At this point I've removed the dash pad, trim panels, air outlets and instrument trim and etc., and I'm at the step where I am supposed to remove the in-vehicle temperature sensor aspiration hose and then the in-vehicle temperature sensor. I don't see a part that looks like what is in the FSM. Searches online didn't reveal anything either. It appears that it is attached to the top of the Heater Core Housing but the airbag is in the way of me seeing down that far.
My question... the FSM doesn't say I should remove the airbag, but that seems like the best way to get access. If you've done this job, info on how you got to this part would be appreciated.

antfarmer2

no help but belive the air bag needs to come out. you did disconnect the battery first and power down by turning the lights on or honking the horn. looking forward to the video for my 94 hope I never need it!!!!!

Bob2.0

Yes I did. Thanks for watching out for me. I can see there are a lot of precautions to removing the air bag, and with the FSM not mentioning it, I may just have to find that part by feel. The great thing about doing this is that most of the wiring is exposed now, allowing me to have a better view for fixing my other problem. Fun five day weekend ahead...

Bob2.0

Well, given that I've had 73 views and no responses to the question, I'll assume I'm in uncharted territory. So I'll go ahead and remove the airbag and post my results as I go. Should be a fun weekend. Wish me luck.

TorchTarga94

Keep us posted, will be good info to have if/when I ever have to replace the heater core on my 94'.

antfarmer2

I have faith in you. just take your time and back off when frustrated. I did many pilot runs in the factory but not on vettes. the IP is famous for hidden screws. when being built on the IP line it is on a carrier that gets fliped up and down for assembly. then it is put over the heater core. might be a good time to buy a scope camera. you will learn a few new words.

mike c4

I have not done this job but i have put in new heater cores in cars my though is remove anything that will give better axcess to the heater core

gdl2165

I recently did the heater core on my 96, I had to remove the airbag in order to get to one of the screws. My FSM has a procedure for removing the bag but I'm out of town for Thanksgiving so I don't have access to it. It said to disconnect the yellow connectors under the steering column, then there was another step that I don't recall the particulars but I couldn't locate whatever it was so I skipped over it. My suspicion is that item was a function to make sure the bag is completely drained of charge but my battery had been disconnected for over a week so I felt I was okay. On mine there was another yellow airbag connector up in the passenger footwell, under the heater core and covered by the carpet. I also disconnected that one just to be on the safe side. Removing the airbag is simple, only four bolts and another power connector. Just make sure you're not directly in front of it as you're working on it just to be safe.

That air temp sensor tube on mine ran from the sensor that's between the two passenger side vents, up and over the heater core case where it connected into another pipe. I removed that intermediate tube but left the actual sensor and what it connects to up inside in place.

One of the more difficult parts of the job for me was dealing with that plastic tube that connects to the front of the case and feeds the side window defoggers. I didn't want to cut it so I went to the trouble of disconnecting it. The problem came when trying to get it connected back up, the end that feeds over to the drivers side connects behind the radio and was a bear to get hooked back up. If I were to do it again I'd just cut the left side and then use some HVAC tape to reconnect it later.

Bob2.0

Thanks for the input. I'm making good progress and carefully recording every step of the FSM fix for a video. I got the airbag out and it helped a lot for getting to the screw you're talking about and for removing the interior sensor hose. I'll keep that in mind about cutting the tube that goes to the side window exhaust. I just removed the wire harness restraint to get at both the screws so we'll see. I'm trying to go "by the book" for the sake of the video but I'm open for time saving advice.
I hope to have the whole project finished tomorrow. Then I need to figure out where my electrical system is going wrong for another problem.
It's always a good time trying to fix these cars.
Thanks to all for your advice, input, replies and encouragement.

Bob2.0

The old heater core is out. It was a struggle, and I'm amazed at how many hurdles there were along the way that the FSM or online research never mentioned. I am carefully documenting every hidden screw, every hard-to-get-to clip and all the little things that would be nice to know for future users taking on this project. It's taking me a lot longer to do it as I am filming it, but I'm looking forward to giving something back to the Corvette Forum community instead of always just taking.
Tomorrow I'm blessed with another gorgeous day... so hopefully I'll get done. My plan is to get it all connected, run it under pressure to test for leaks, then put the housing back together, track down the short that is causing my other problem, and have my car back again, ready for winter.
More later...

antfarmer2

take both cores to a rad shop and let them ajust the new one to match the old one and test it

Bob2.0

I would but I bent the old one because I didn't know about the clip holding the top of it down. Not a word in the FSM about it. I test fit it though and the new one lines up with the holes in the firewall.

Fun day ahead....

antfarmer2

post what kind it is with where you got it from. never heard of one that fit right yet!!!

Bob2.0

The aluminum is extremely flexible so I'm guessing that as I ran it through the firewall the act of shimmying it through the space caused it to line up. At this point however, I ran into a new problem that pushed the repair into another day as the radiator surge tank return inlet hose is a special item that is 15/16 at the tank and 3/4 at the top of the heater core. Another missed piece of info that would have been nice to know BEFORE cutting off the old one. At one popular parts store they didn't have it and couldn't get it, at another they couldn't find it but tried to come up with a solution, but ultimately O'Reilly's found it at a store in Nashville, and is sending it to Bowling Green for me to pick up at 10:30 a.m. Way to go O'Reilly's. I'll include the part number in my video to save others the inconvenience of a mid project interruption.

WVZR-1

The hose for a **later C4 certainly should be on the "buy now" list when buying the heater core. It can be challenge locating so it will be good for you to post. From O'Reilly it needs to be a 19743 or equivalent if they used a different source for you. If it's other than the 19743 I'd confirm before making the drive.

**'90+

Bob2.0

That's the one I ordered so we're good... if it ever comes in. Not on the next truck either. My last chance for the day is between 5:00 and 7:00. You are right about that list. When I post the video I will for sure have a "buy now" list to go with it.

Bob2.0

At long last I finished the installation of the Heater Core. After all that work it was really rewarding to feel that heat blasting out. I didn't realize how bad my last core was performing until the new one was in. I didn't film the reassembly although I wish I would have as there were a couple of things I learned that might be useful. I'll include it in the video anyway. Thanks to all for your help. I'll let you know when the edited video is posted so you can give me your feedback on it. Now, on to my next C4 Fix...

antfarmer2

good job

gdl2165

Congrats! Gives a great sense of accomplishment, doesn't it?

Bob2.0

It does. Just like when I changed my first opti, it was like joining a fraternity of those who have done it. Now when someone mentions their heater core at a Corvette function or here on the forum, I can nod knowingly and offer them tidbits of timesaving wisdom. Thanks again to everyone here who gives of their wisdom to keep these C4's running.