C3 - HVAC Fan, Insulation, & Carpet Update

[Lee74C3]

I took Friday as a vacation day and made a three day assault on the 1974
Coupe. Insulation, rebuild heater box, heater core, new blower motor with
larger fan and 7/8" spacer, carpeting, and a whole bunch of other interior
trim pieces.

I am happy to announce... my HVAC fan no longer SUCKS (!)... it BLOWS (very
hard). The fan recommended by Ernie at Wilcox (p/n 52466047) does make a
difference. In addition, I sealed and taped all connections for the ducts
and repaired the plastic connector that moved the temperature door. I
still need to get the AC charged. I get significant air flow from all
outlet positions.

I had the entire dash out of this car. Despite taking good notes at
disassembly, I was apprehensive about connecting voltage to it again. I
pushed it out of the garage (my wife would really hate it if I burned the
house down), placed a big fire extinguisher in close proximity and, got out
the BIG bolt cutters in case I had to cut the battery cables fast.

First, I connected the battery cables and was pleased that buzzers buzzed,
dash tell-tale lights came on etc. After letting the car sit for about 10
minutes and not seeing any smoke, I turned the key to start... and it
started right up! Except for two items noted below, everything works.

I do have two small issues yet to sort out and would welcome suggestions.

1) The right side plenum vent door (which I rebuilt with a new seal) opens
when it should be closed. It is closed in all positions except AC MAX. In
AC MAX, it opens. I think I have a vacuum hose(s) connected in the wrong
place. Which one and where?

2) The vacuum switch to override the headlamp doors... I can't figure out
what it was attached to under the steering column area. Maybe something is
missing on my car. The trip odometer reset is in place (it is hard to turn
due to bends in cable). It appears the headlamp switch is mounted inboard
of the odometer reset... where? The AIM is unclear in this area.

FYI - the ACC carpeting I purchased from Wilcox looks great. It required
very minimal trimming. The hardest part of the carpeting job is the
wheelhouse area on each side.

Thanks to everyone who provided guidance in this project.

 

[Bob Chadwick]

I am happy to announce... my HVAC fan no longer SUCKS (!)... it BLOWS (very hard). The fan recommended by Ernie at Wilcox (p/n 52466047) does make a difference. In addition, I sealed and taped all connections for the ducts and repaired the plastic connector that moved the temperature door. I still need to get the AC charged. I get significant air flow from all outlet positions.

Tells us more about this. Was it just a bolt up replacement or did it require significant mods? This fan comes out from the front of the car doesn't it rather than from under the dash?

Originally posted by Lee74C3 1) The right side plenum vent door (which I rebuilt with a new seal) opens
when it should be closed. It is closed in all positions except AC MAX. In AC MAX, it opens. I think I have a vacuum hose(s) connected in the wrong place. Which one and where?

As I recall the door position is not as obvious as you might think. I thought mine was working backwards as well until I stuck my head down there and listened to it. It was clear that my initial perception was wrong. Absent hooking the wrong vacuum hose to the actuator, most likely at the vacuum attachment at the center console I don't see how you can go wrong here.

Originally posted by Lee74C3 2) The vacuum switch to override the headlamp doors... I can't figure out
what it was attached to under the steering column area.

The switch mounts on a plate that goes across the steering column. As I recall it mounts across the opening for the lower steering column cover and the cover goes over the top with the over ride switch just coming out just behind it. I can't remember if it screws into the lower dash pad or if there was another set of screw holes; I think there were another set of screw holes.

 

[Lee74C3]

The blower motor and fan come as one assembly and is the same bolt pattern as the original motor. The fan itself is 1 inch deeper and has a different pitch to the blades. You must make a spacer at least 3/4" - 7/8" thick and user longer bolts to attach to the housing (yes - from outside under the right fender).

Vent door - I do not have the kick plate installed yet. With no vacuum (engine off), the door is in the closed position. It stays closed on any position except AC MAX. This seems to be the opposite of how it should work. I realize this may be difficult to screw up. I didn't disconnect any of the hoses from the connector at the console HCAV control and there isn't much else to get wrong.

Headlamp Vacuum override - I think I'm missing the part under the column.

ps - by the way, your postings and web site were particularly helpful in my project.

 

[Bob Chadwick]

Glad to have been of help. I actually went to Corvettefaq.com for something else and saw a HVAC tutorial. Looked to see if there was anything I could add to mine and lo and behold, it was my web page.

Do you have pictures of what you did on the fan. With everything I've done to mine it has gotten cooler inside but I think greater air movement will significantly enhance what I have already done.

Closed may actually be open sealing the vent so that outside air goes into the system rather than preventing it from being introduced. The only thing there is the single vacuum line. I would suspect that if it it is moving the door then it is working right.

There was a metal piece that bridged across the column with the over ride valve screwed to it. Now that I am thinking about it further I think it may have screwed to two inside holes on the pad and then the cover screwed to two outside holes. I've got it all back together but it shouldn't be two hard to take it off and get you a couple of pictures if no one else can clarify.

Bob

 

[Lee74C3]

Sorry... I don't have a digital camera (yet). I'm laying low given what I spent this winter on the interior. Now that the weather is warming up and I can get the car outside, I'll shoot a photo of the spacer with my 35mm and post it.

Using the old motor, I made a cardboard template and cut the spacer from high density plastic. with a band saw and router. In retrospect, it would have been easier to use a picce of oak or marine plywood.

I share your opinion on the plenum door. I'm not sure if closed is open or open is closed!

 

[Bob Chadwick]

Sounds good. How hard was it to open the box under the hood. I have looked and to be honest, I'm not sure that I can find all the screws.

 

[Bob Chadwick]

Lee,

I have used your material on the web site I published on heating and cooling the vette, giving you full credit for your ideas. Take a look and let me know if you have any problems or concerns.

http://home.attbi.com/~jchadwick/ventilation.htm

Bob

 

[Lee74C3]

Bob:

The summary at your web page looks great. Gosh, do I get royalities now?

I'm not sure I understand your question on opening the box under the hood. Since I don't think it's pandora's box (it really is) I'm going to assume you mean getting to the Fan/Blower.

Actually it not too bad to get at with a few preliminary steps. It is a tight fit though. My car is a big block, I think a small block might be somewaht easier.

Ok...

1) Loosen the AC compressor mounting bolts and loosen the belt (just flop it off the pulley). DON'T OPEN ANY AC HOSE FITTINGS!
2) Remove air cleaner assy (do this first)
3) Remove engine oil dip stick and tube. It is held in place by one of the exhaust manifold bolts at #6 cylinder. With the bolt removed, simply pull it straight up out of the oil pan, it is just a pressed in fit.
4) Remove one bolt that holds the AC sight glass in place near the radiator overflow tank. You will need to VERY CAREFULLY bend it VERY SLIGHTLY out of the way for a later step.
5) Remove the two wires on the AC presssure cutoff switch which is part of the sight glass assembly
6) Jack up the right front and place on a jack stand
7) Remove the RF tire
8) Locate the three bolts in the rear of the wheelhouse area that hold the radiator overflow tank in place and remove them
9) Pull the cap off the overflow tank and squeeze the tank out of the engine bay. It is a very tight squeeze and here is where you must force the AC sight glass out of the way a little. There is a bit of a trick in turning the tank to the right angle to get it out. Remember this trick, as you will have to reverse the move to get it back in. Getting the tank out is the hardest part of the job.
10) You now have very clear access to the blower motor and can easily get it with a 1/4" drive ratchet with a 4" - 6" extension. The wiring is pretty simple. Just remember that the orange wire was never attached to anything before you started so don't attach it to anything when you close up. Actually, this would be the hot lead to the motor on a NON AC car (at least that's the way it is on my 1974)

Again, the hardest part is getting the overflow tank out. While I had it out, I flushed it out with my pressure sprayer after using a baby bottle brush and some Simple Green. I then put about a half cup of clorex bleach in the tank and filled it with water. Let it sit for a half hour and pressure wash again and the tank looks like brand new.

 

[Bob Chadwick]

Good instructions Lee. Thanks.

Of course you will get you royalties. How does that song go? "nothing from nothins is nothing".