I thought I'd get my A/C operational for the first time.
I have a 68 vert with the factory A/C option. All parts seem to be in place, but the compressor was seized.

We have extreme hot weather in South Australia.... it sits over 100*F for many days at a time in the summer.....

And there MUST be some truth in what the geeks say about that hole in the ozone layer too, because I can't handle the roof off on a cloudless midday cruise. The radiation is much more intense than I remember as a kid.

I must be showing my age

Anyway, the factory AC Delco compressor was seized, and after making a few enquiries, most C3 vette owners I asked told me that the factory A/C system is just is NOT sufficient to handle our Ausie summers. So I didn't bother to repair it.

After 10 years of tolerating our summers, often deciding against using the corvette due to heat, I have decided to get it working again.
Instead of the ACDelco compressor, I bought a compact Sanden unit.
Lighter, smaller, more efficient and it's designed to use R134a gas.

I made a suitable mounting bracket from 10mm Aluminium plate, and got it positioned to align the belt drive pulleys. New fittings suitable for the sanden compressor were fitted to the hoses, new connector O-rings were fitted and the system regassed.
Fired it up, and " presto" cool air from the vents. woo hoo

The blower fan is noisy and doesn't blow a lot of air, so I will look at alternatives from our Australian GM Holden models of the same vintage.

I am however, having a hard time finding good information on the A/C control functionality. I don't have an owner's manual, so I am uncertain of the correct operation of the two thumbwheel controls....

I do not have control over the vents.... I guess my vac lines are not hooked up correctly.

Where can I find a good reference on the A/C control system for a 1968 corvette?

 

There is a book" A/C strategies for corvettes" that has a wealth of info on making the a/c work to its max capacity. The book is out of print last time
I checked but I got a copy from ebay. Specifically for your car maybe someone here will chime in that owns that model. I believe vette magazine had a rebuild of controls on their website. Check it out.
Good luck

 

http://www.corvettemagazine.com/2001...-panel/ac1.asp
Is this the article you are refering to?
Great site with LOTS of tech info.... thanks.

Well I think I may have solved part of my problem....
Zip site shows 68 control panel as this ???


My A/C heater control panel looks like this....



So can I assume that left thumbwheel controls temp setting.... gets warmer as dial goes to bottom. Right thumbwheel is vent controls .. ???

 

Left thumbwheel is vent controls, right thumbwheel is heat control...

Joe

 

The first control is for a 1968 only with air cond. The second control is for a 1969 to 1976. On the second controler you can see a c at the top and a h at the bottom of the right wheel. This is for the hot and cold. When you move the wheel it make the cable on top of the heater box open or close the hot air door.

Here is a schematic for a 68 a/c car http://www.docrebuild.com/dr-r-web/9222104.HTML

Here is the 69 to 71 a/c http://www.docrebuild.com/dr-r-web/9222105.HTML

 

Hmmmm.......
I have a cable controlled by the left thumb wheel going to the bottom of the heater box.... I'm sure that it controls the hot air door.
Please note that my car was converted to right hand drive, so heater box is different .

I'll try and chase down the book "A/C strategies for Corvettes" that jb referred to above.
Need to get a full understanding of how the whole system is supposed to function, so I can find a solution to my customised rhd A/C system

I just found the vent doors behind the kick panels are spring loaded closed, and after consulting the AIM I noticed there should be vacuum actuators.

Looks like I might have more work here than I anticipated

chhers

tom

 

Hmmm...

There are some dreadful things done during RHD conversions, so it is going to be necessary to figure out what's been changed, left out, disconnected and bubba'd by the converter.

I'm not familiar with 68 controls but i have worked on 69 controls and the control panel in your post looks like a 69. Do you have vacuum circuits connected to the rotary vacuum switch on the left hand wheel? Do you have a vacuum operated hot water shut-off valve connected to the vacuum switch on the right hand wheel? Does the demist system work or is the air directed to the vents continuosly?

What kind of conversion was done? Mirror image, cross-shafts or chain drive?

I agree that the AIM and the book you're chasing would be good help. Unfortunately I'm in Melbourne and it will be hard to diagnose a modified system without seeing it, but I'm happy to help.


Joe

 

Thanks for chiming in Joe...
There are vacuum hoses connected to both left and right controls, but some of them are looped to each other and perform no function (other than sealing the vacuum line) I am assuming these would normally go to the side footwell fresh air vent actuators.
I only got the A/C operational for the first time yesterday, and the left control, as rolled downwards, will switch the A/C on as it passes the MAX A/C indicator. As I continue to roll it downwards, there is no change to the ventilation pathway. Cool air blows out of the two side vents AND the centre vent, but not much comes out of the footwell vents. Moving the right control doesn't appear to do anything.

Like I said in previous post, the heater door control flap is cable connected to the left control, but I didn't notice any warm air coming in... in other words, there was NO mixing of cold and warm air?

Without seeing a complete diagram and explanation of the entire A/C heater system, it's difficult to fully understand where my problem is....

Joe, I am not hung up with the concern of getting it working as per factory original 1968 specifications.
What I want to do, is get a functional A/C system that actually works for conditions in Australia. I have never had any air flow in the cabin before, so even getting the existing fan operational was good. Found the connector to the fan unit had come off. But blowing COLD air out of the vents is an awesome bonus. Now I want to get some control over it, and will eventually remove the existing blower fan and replace it with one from a Holden.... which should blow more air... do you have any advice on which models may be suitable... eg HG or HQ?

cheers
tom

 

Yep, seems to be bubba'd

The side footwell vent should have actuator controlled by the LH thumbwheel for outside air. Looks like yours is rigged for recirculate only. Is the air valve in the plenum above the blower motor operational?


The RIGHT thumbwheel should have a cable that operates a mixing door for hot/cold air as a temperature control and in the full cold position should turn off the vacuum operated hot water valve. (this part is a little different on the 69)

Does your demist work? does the heater work?

Regarding the blower motor, does the high speed fan relay come on? This needs to be there and operational otherwise the fan doesnt run at full speed. The AIM can be a big help getting this right.

Lastly, I'd imagine an early holden blower motor will work fine, but it's worth making sure the existing one is OK first.

Joe

 

One option you might consider is a kit from a vendor like Hot Rod Air. They seem to have a very good system and one of their universal kits might
work well for you. They have kits for your specific model however since you are now right hand steering I think a universal might make more sense.
It's real easy to nickel and dime your self to death trying to fix factory air.
Good luck

 

Tom,
I will be in Adelaide next week for work, any chance I can help out in the arvo or evening? Could be some of this as well.

 

The 1968 Chevrolet Chassis Service Manual is probably the best source for information concerning the 68 Corvette A/C system.
Bryan

 

PM sent!

 

I considered a kit, and if I had to install A/C from scratch, it would be a sensible decision.

I have about 90% of the factory system in place though.
Only fresh air vac actuators are missing, and I might need to spend a bit of time deciphering the control system.

I'm sure that I can get my components to work well enough for my needs. There is cold air coming out now. Just need to optimise the vent controls and add some more flow.

 

I have the 1968 AIM, purchased from Mid America.
Where can I obtain a chassis service manual for 1968 vette?
I can't find it listed?

 

PM recieved!
Wheels of Time in Dandenong (Melb) should be able to help you, don't know if you have a specialist "Motor Books" store in Adelaide.
Ask the Guys and Gals at tonights meeting

 

If you buy another 'complete' aftermarket A/C kit [for an A/C car], it will need to have the controls working properly as well. So, I suggest that you continue down the path you are going and just finish refurbishing the system as it was installed in the car. From your discussion of how the system is acting, I am guessing that your heater is not working....or you checked the operation of the controls before the engine had time to warm up. In either mode, A/C or heat, the temperature control should be operational. The temp control simply regulates the outlet opening of the heater into the vent system. So, if you operate in A/C mode, and the temp is too cold, you can still warm it up a bit by adjusting the temp wheel. On the other hand, the "mode" wheel will select A/C (with MAX-recirculate, bi-level, and normal settings), vent, heat, or OFF positions. Each mode setting places the various vent system doors in different positions to achieve correct operation. As mentioned, the GM Service Manual is a "must have" for what you are doing....assuming that your system is similar to the factory design. If it is not, you will have to query the company who modified the car, as GM will not be able to provide information on those changes to the design.

 

I know you can get it off the NCRS website. I bought my 68 Chassis and Overhaul manuals off of ebay. These manuals have all the information in them to rebuild practically all components on a 1968 Corvette.

My a/c system has been rebuilt back to original 68 configuration. It's going into the shop tomorrow for a R12 tune-up for the summer. I finally found an original 68 brass heater hose control valve that I'm going to install.

Bryan

 

Thanks for the leads guys...

Hey Bryan.... verrrryyyy nice 68 vert

 

If you click on the link in my first post you will see a drawing of the vacuum hoses and where the go to.