LouieM

The factory air conditioning on my 67 is blowing cool not cold. I tried hooking up a saved-up can of R12/freon but it would not go into the low-pressure side at all, as it should. The Schrader valve on the low-pressure side is working, and there is freon in the can -- so maybe the system is fully charged as it is? If so, what would cause the air coming out of the dash vents to be only a bit cold? The fan blower works, and lots of air comes out the dash vents, but the air is cool not cold. Before I go to an AC shop and get the system recharged with freon, does anyone have an idea on what this problem could be?

Question #2 - Anyone done a conversion from freon to 134? Can you do this at home? What's involved? Do you just have to replaced seals and gaskets, and maybe hoses, or what?

plaidside

To properly diagnose an A/C problem you need to hook up high and low side gauges and interpet the readings. In order to charge through the low side the pressure has to be lower than the pressure in the can.
There are may possible reasons for the lack of cooling.
Some are, too much freon, low freon, bad or clogged expansion valve, bad POA valve, too much oil in the system and many others.
As far as the 134 conversion the biggest task would be to remove all the mineral based oil from the system. The only sure fire way is to disconnect all components and to drain them. To use 134a you must use a compatible oil to keep the compressor lubricated.

blitz10

I had my 67 A/C worked on this spring. I had a leak in the evap core. I bought a new one and heater core for while the mechanic was in there. All new hoses, drier. Converted to 134 and it blows cold. I bought all the parts and this included seals, both inner and outer for the box. Air volume is what suprised me, it is like a hurricane now. I did have deteriated hoses under the dash and was loosing a lot of air behind the dash.

Viking427

IMO, don't convert to R134 unless you have to. Besides the expense, its very obvious under the hood. There are more alternatives out there today than yesteryear. I believe DuraCool and at least one other mixture offer comparible performance and are compatible with R12 oil/hoses etc.

dennis-trapp

Say Blitz
Could you explain exactly how you managed to get it to blow like a "hurricane"? What? Where? How?
Dennis

Nicky71

Mine had been converted to 134a before I bought it. It was a real hack job. A 134a conversion can be made to work well, but it will never cool as aggressively as the original R12 system.

Does anyone have a good resource for rebuilding the A/C system on a midyear? The factory manual has a lot of info, but I am starting from scratch with mine and would like to consult other sources as well.

LouieM

Based on plaidside's comment, I'd better get the system checked out before doing anything. Here in the SF Bay area, the World Capital for Overpriced Everything, freon costs $65-90 per pound, and will only go higher in the future --- and a midyear system takes 3 pounds. R134 costs $12-15 per pound --- quite a difference, $36-45 versus $195-270 for 3 pounds of gas. I've been quoted from $200 up to $1,000 over the phone to convert to 134. I'm fairly sure that a 134 system would cool a cabin as small as a midyear's, since the system was designed for a fullsize Chevy --- anyone have experience along those lines? My preference is to stay with R12, since a good charge will last years, and I have a few cans of R12 at home. Has anyone coverted to 134 themselves at home? I would not mind taking apart all the AC components under the hood, though I'm not sure how to get rid of ALL the oil from the compressor. Do you just blow it out with an air hose? Or flush it out with alcohol, then blow it dry with an air hose, or what?

If I do convert to 134 this might be a good time to swap out the huge factory AC compressor for the much smaller modern ones, such as from Vintage Air. That way I could actually get to spark plugs 2 and 4 without without doing contortions like a young-girl Rumanian gymnast. Right now I can't put back the shielding over plugs 2 and 4 because my hands are larger than the available space.

This is all starting to look like a more expensive job than I anticipated...... :rolleyes:

Doc Rebuild

Gentlemen,

When my 1967 was restored, I personally refurbished the AC system under the dash and on the outside face of the firewall. When I returned those parts to the shop doing the rest of the car, they flatly stated that they could never devote that time or effort. So the simple answer is do it yourself.

The metal outer firewall evaporator case is a straightforward refinishing job if the steel is not severely corroded or missing a piece. Since this case is metal on 1963-1967 and water condenses every time the AC runs, I made sure the inside walls were better painted than the outside. Meaning they had more coats. At the spot welded seams between the floor and the walls of the evaporator case I added a bead of weatherstrip adhesive to further protect.

As you may know the inner walls of that metal case are lined with sponge rubber. After installing new sponge rubber seals, fill the seams between these flat rubber seals with more weatherstrip adhesive to further protect the metal case. C3’s and later have plastic cases and do not have this rust problem.

The evaporator core has a screen for protection for organic debris, however I added another directly behind where the case mounts to the plenum. Hopefully this will minimize organic debris from entering the case itself from the plenum.

The inner boxes and duct work are wood chip plastic and can be repaired with epoxies and filler. On the main inner box, I removed all this small semi-tubular rivets to remove the inner steel partitions and plates. The steel plate that separates the heater core from the back of the case must be removed to access the door that allows hot air to flow. After the internal steel parts were refinished and installed in the refinished cases, I lightly coated the plastic cases with semi-clear spray to give them back a semi-sheen. During the refinish of the cases, I have cleaned and sanded them with 600 wet paper. Others have stated they used wax.

All in all, my 67 427 AC blows as cold and as forcefully as my C5.

Geoffrey Coenen
NCRS #2473
NCM Lifetime #105
Precision Valley Corvette Museum Charter Member #20 (I think)
Retired #1 56, 63, 67, 68, 68, 69, 75, 99 and I want more! :D
Wanted: 1969 L-89 conv (no project)

repruet

Doc, in your cat. Volume 27 on page 52 I see an STV conversion kit. Is this an easy novice type job to do or does it need to go to a A/C shop? I recently purchased a 66 coupe 327 w A/C and went to charge the system and oil and gas came out the STV valve almost as fast as it went in. I can't decide whether or not to convert or to try your STV repair valve.

I just placed my second order with Dr. Rebuild yesterday.

I am still mulling over the STV problem so any info you care to share would be greatly appreciated.

Thanks

Rodney

Doc Rebuild

Sir,

I’ll just provide some basic information about this air conditioning update solution. The factory designed STV has a diaphragm that is failure prone.

In this jpeg - http://216.149.148.95/stv-update-kit.jpg - in the upper center is a block of block-off plate and seal for the STV. Also included is a new electrical sensor with a probe to wrap around the upper evaporator core pipe and putty seal for insulating that sensor. A small harness and with connectors, a sealer and full instruction make this a simple conversion.

Geoffrey Coenen
NCRS #2473
NCM Lifetime #105
Precision Valley Corvette Museum Charter Member #20 (I think)
Retired #1 56, 63, 67, 68, 68, 69, 75, 99 and I want more! :D
Wanted: 1969 L-89 conv (no project)