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Hi Tooch,
Perhaps you could post the relevant pages from the C60 section in your 73 AIM.
E1 and E2 in my 71 AIM.
That might help!
Very strange to me that the controller in John's pictures appears to be set up for both a/c and a-v control. ?!?
Regards,
Alan
Maybe it's been modified over the years?
Alan,
I know you'll probably know this but did the AC cars have "Astro Ventilation" on the side windows?
Hi thea,
I believe the Astro-Ventilation script appeared on all side windows on cars built from the start of 68 model year through the 75 (?) model year.
Regards,
Alan
Hi Tooch,
I deleted most of my response to your photos.
Perhaps you could post the relevant pages from the C60 section in your 73 AIM.
UPC C60, Sheets E1 and E2, in my 71 AIM.
That might help!
Very strange to me that the controller in John's pictures appears to be set up for both a/c and a-v control. ?!?
Regards,
Alan
The more I look into this, the stranger it is. According to another picture in the 73 AIM, it confirms your thoughts as well, in that there should not be that part on the right side of the Heater/AC controls for vacuum hoses to attach. The right wheel on the AC cars only controls the Bowden Cable, which controls the temperature door in the in selector duct assembly. Maybe a previous owner added that for some unknown reason, unless the AC didn't work and he tried to get the Astro Ventilation to work????? It would be great as you asked earlier if John can find out exactly where those two hoses on the right side are connected....
Tooch
My cars a very early '73. VIN ends in 00045 and I think the build date was 14 August 1972. Don't know if that's relevant.
Regards
John
John,
I'm trying to come up with a solution for you. I have a couple original c3 owners checking on this too.
BTW, that is really a low vin number. If you don't mind sharing, what engine, tranny, options, and color is the car?
Regards, Tooch
Tooch,
Thanks for the interest. It's high compression 350, 4 speed Rock crusher. I assume a/c was an option, it has power steering and power windows, leather seats. The color is a medium blue metallic. I've attached a couple of photos(from when I bought the car) that may help you identify it.
Tooch,
Thanks for the interest. It's high compression 350, 4 speed Rock crusher. I assume a/c was an option, it has power steering and power windows, leather seats. The color is a medium blue metallic. I've attached a couple of photos(from when I bought the car) that may help you identify it.
Thanks for the pics.
Nice color.
Are you sure about he Rock Crusher M22? They weren't available in 73. The L82 would have the close ratio Muncie. M21.
More pics would be great!
Thanks,
Tooch
OK, I've just had an email from my pal in Australia about that right vac control. He says:
"The car certainly doesn’t have Astro Ventilation.
With the small valve on the right, the top nipple is vacuum source, the middle is vented and the bottom goes to a heater water flow actuator mounted low down on the outside of the firewall in the engine bay. The roller wheel that actuates that valve also operates a Bowden cable to (I assume) also operate a mechanical valve as well."
That means it looks like nothing in any of the diagrams I've seen. A one-off early in the MY build?
OK, I've just had an email from my pal in Australia about that right vac control. He says:
"The car certainly doesn’t have Astro Ventilation.
With the small valve on the right, the top nipple is vacuum source, the middle is vented and the bottom goes to a heater water flow actuator mounted low down on the outside of the firewall in the engine bay. The roller wheel that actuates that valve also operates a Bowden cable to (I assume) also operate a mechanical valve as well."
That means it looks like nothing in any of the diagrams I've seen. A one-off early in the MY build?
Great news!
At least we now know where the hoses lead to. Although it's still a mystery why they don't show them in the 73 AIM for AC cars. Yes, the right thumb wheel uses the Bowden cable to operate the temperature door in selector duct assembly. BTW I posted a thread about this on the NCRS TDB and haven't heard anything back. It would be interesting to see if those hoses show up in the 1972 AIM for AC cars. Which would certainly explain the carry over to your very early 00045 car. Maybe someone on here could check and post a pic..
Thanks for the update
Jimmy
I'm certain you're right about the M21. It drives like a close ratio. The dealer I bought it from was adamant it was a M22, but then he's a dealer.
I bought the car in early 2015 to do a rally across America that year. If you're interested I did a very amateurish Facebook page to keep our friends back in Australia in touch. It's a bit long winded because it starts in Denver, goes to the start in Halifax then most of the way back to Denver.
I'm certain you're right about the M21. It drives like a close ratio. The dealer I bought it from was adamant it was a M22, but then he's a dealer.
I bought the car in early 2015 to do a rally across America that year. If you're interested I did a very amateurish Facebook page to keep our friends back in Australia in touch. It's a bit long winded because it starts in Denver, goes to the start in Halifax then most of the way back to Denver.
I can't say the a/c has ever worked PROPERLY but...when we were on our way to the start of the Trans Am in 2015 we dropped into (thanks to CF members for the recommendation) Tony's Corvettes in Gaithersburg, MD. We'd just spent a couple of summer days in DC and we're getting desperate for a/c.
They couldn't have been more helpful. Great shop. They sucked the a/c system dry and reported no leaks on vacuum. But when they recharged it, we could hear hissing from the compressor. Obviously a leak there when under pressure.
The upshot was that we got a little coolish air until the gas ran out. So it worked a bit, but only that. Air flow was very low. I also suspected the heat was staying on a bit, so we cut the heat feeder hose and put in a manual tap. That helped but a Corvette in mid summer with only windows is a place to avoid. My wife and I hit 110F in Sacramento in the car on the way back to Colorado after the rally. I'm surprised are still married!
Meantime, back in Australia, Jeff has pulled the whole console to bits and reports the left drive wheel is stripped, so I've ordered the centre replacement kit and both vacuum controllers from Ecklers. It usually takes about 3 weeks for parts to get across, but they should go a fair way to fixing the problems. We've also fitted a new compressor and will obviously convert to R134a. Like America, we can't get R12 in Australia any more.
It's certainly looking like an early production run anomaly. When I looked at it, and from Jeff's photo that I posted at the beginning, it all looks factory. It's usually pretty easy to spot aftermarket installations. Under the hood, the a/c chamber on the right firewall all looks factory.
The only thing that looks strange is that the hoses from the compressor to the condenser and chamber are far longer than they need to be, with the excess tucked up beside the fender. My though for that is that some time in the car's life, the original compressor gave up and got replaced, along with the hoses, with one from another car that had longer hoses. I don't know, but wouldn't think, that GM used very long hoses originally.
Was this car originally built for U.S. sale, or was it slated for foreign sale? The difference in the control 'guts' could be due to differing national requirements. Or, that control could just be cobbled together 'after-the-fact' from "available" parts. Normally, the left-side vacuum manifold would have supported the control of the water shut-off valve. Is that left-side manifold differently constructed (number of fittings, etc) than what should have been standard on the '70 A/C cars? If so, that right-side manifold may not serve any function at all.
To the best of my knowledge it was originally built for US sale. Back then I don't think any were built for export. Others will know this better than me.
My left side manifold has 6 hoses and 3 ports as the AIM for 1973 in one of the above replies shows it should. The right one is the anomaly. It controls the hot water valve on my car.
The '71 AIM shows the left manifold with 9 ports...7 of them used (plus 2 that are used as vents). So, after '71, perhaps Chevy moved the hot water shut-off valve to the other side so that it would always be OFF when the temp control was set to "COLD". That would have been an improvement over that valve being controlled by the selector wheel, IMO.
I'm gathering that the '73 control should be different from earlier versions.
The more I look into this, the stranger it is. According to another picture in the 73 AIM, it confirms your thoughts as well, in that there should not be that part on the right side of the Heater/AC controls for vacuum hoses to attach. The right wheel on the AC cars only controls the Bowden Cable, which controls the temperature door in the in selector duct assembly. Maybe a previous owner added that for some unknown reason, unless the AC didn't work and he tried to get the Astro Ventilation to work????? It would be great as you asked earlier if John can find out exactly where those two hoses on the right side are connected....
Tooch
My '72 AIM page is identical to this '73.
The '73 did not have a shutoff valve in the heater hose. '75 on did. I'm wondering if someone tried to incorporate a vacuum shutoff valve to keep hot water out of the heater core much like some of us do with a manual shutoff valve spliced into the hose.
Just out of interest, someone on eBay has a control unit for sale that seems to have the same controls as mine on both sides:
http://www.ebay.com/itm/1968-1976-Corvette-C3-AC-Heater-Control-Assembly-OE-/152370011359?_trksid=p2141725.m3641.l6368
Please note that I'm not suggesting the seller is an expert in dating Corvette parts, but his ad does suggest some years were set up the same as mine currently is. Maybe 1975 on as F4Gary states?
01-09-2017, 06:22 PM
