First thanks to all that helped with my blower motor not working... was the relay and now working great.

as soon as the blower motor was functioning of course I checked the AC and the compressor is not kicking on... no change in idle however I can see my volt meter gauge drop just a touch when I hit the switch.
The original owner of this car passed in 2012 when the daughter purchased it from the family and has only added about 2k miles in that time (16k total miles on original equipment) so i did not have high expectations as they lived up north and never used the AC while she had it.

I would like to begin my trouble shooting and eliminating now... I checked for power at the compressor and nothing, I know there is a low pressure switch in line and likely why no power is getting to the compressor... much like with the blower motor I know little about the AC and how to service it but will learn quick.
* I have no AC quages so should I start there and buy some... then how do I check pressure?
*can I check for power to the low pressure switch and will this tell me if thats whats going on?
*I have no problem with getting R12 and would prefer stay with the equipment on the car... should I seriously consider converting to r134... outside of availability is there that much improvement and is there conversion kits out there for my car?

There is some pressure in both the fill valves going into the evaporator and coming out... only places I can check

Thanks in advance

 

I would see what pressures are static.
not knowing history is a wildcard.
if refigerant very low i would evacuate and check orifice for debris like compressor parts.
Check for leaks and r12 and a little mineral oil if thats whats in there, and try it.
You can also for a very very short time jump clutch switch and verify not messed up.
a few threads on mine as i was in same scenario low mileage not working.
https://www.corvetteforum.com/forums...s-oriface.html

https://www.corvetteforum.com/forums...questions.html

 

Great thank you... I thought there was a way to bypass that switch.

 

Morning golfobsessed
I'll start.
I am very familiar with ac in my 69. Your setup is a bit different.
I'd stick with R12.
If you have located your low pressure switch just jumper the two wires, turn the key to ON and turn on ac. You should hear a clunk. That is the electromagnet closing the clutch on the compressor. I bet it works.

Next you do need a set of gauges that read R12 so you can hook in to your system and read pressure. They are kinda hard to find. There are adapters for 134a pressure gauges if you cant find r12 gauges.
Since you have pressure in the system that's good. Static (compressor not running) should be around 80 if your garage is about 80 degrees. If lower, like around 30, add a pound or so of r12 and see if you get some cool air. You will have to jumper the switch to get some more r12 in the system.
Report back. If you don't know how to add r12, report back.
VS

 

perfect... I am reading up on all this, I will order a set of r12 guages... I see most will do both and check current pressure. I am reading about jumping the pressure switch as well to check compressor.

I am not concerned about buying new components... would be good to know what I need.

 

Make sure the gauges you order have fittings that screw in to R12 pressure valves! The 134a valves are totally different.

If you are using cans of R12 and want to tap them without going through your gauges you need an R12 configured tap.

Does your system have a sight glass on top of the receiver/dryer accumulator? On my 69 its located at the passenger side by the nose.

VS

 

thank you... most I've seen have fittings for both, not seeing much dedicated to just the r12, think I'm just going got order a setup from Amazon as I dont need high end stuff for what could be a one time use.
I do not have a sight glass on my dryer like yours

 

Just spit balling here... deciding on direction.

I have no problem buying new serviceable components which I would assume most commonly compressor, orifice tube and perhaps O rings and flushing the system... is that as simple as evacuating, removing tube and compressor and just adding a solution and blowing through with compressed air? Would an r12 compressor even still be available?

Or should I "see what I have" by checking static pressure and im assuming bypassing switch to check running pressure and compressor and go from there.

Again I dont mind buying new components but if not necessary there are allot of tight spots to get to and would prefer just charge if thats a solution,

I understand freon doesn't go bad so if its low then there is some kind of leak but there is still pressure in the system so its holding something... could this be a simple as a possible top off charge every year or so.

 

One of the first things I would do is go to AutoZone or someplace similar where you can rent a vacuum pump with the proper connectors to the compressor muffler. Pull the vacuum on the compressor and once complete, let it sit to make sure it is holding pressure. If it's not, then you will have to address that before any recharge.

 

is this a method of testing the compressor? I would like to apporach this from a position of status... what's good and whats bad.

 

Golf

Here is what I would do assuming your compressor clutch works after jumping the low pressure switch.

As you indicate its holding pressure after all these years I see no need to evacuate the system nor clean out the pipes. Oil will still be good, too. Only thing that could be in there is r12.
If you have a can tap that will fit on the LOW PRESSURE side run the car up to 2000 rpm and open the valve on the tap.
turn your now working blower fan on high when charging. Don't invert the can, just shake it. If it's taking freon the can will get very cold. You might want to put on a glove.
At this point you reconnect the low pressure switch. If you got 12 ounces of r12 in there the switch should complete circuit to compressor on its on.
Don't worry about getting too much r12 in the system. It's really hard to overcharge R12, unlike 134a.
Now see if your vents are cold. If so, try and squeeze another can into the system.
Hope you get lucky!
(I've put r12 refrigeration in sailboats as well as fixing old cars. I am pretty good at getting them to work. My 69 loses about a pound every year. I have 47 pounds in a canister so I am probably good. . Can't find the leak, even with my electronic sniffer.)

VS
VS

 

It's a way to check system for leaks. If after pulling vacuum it holds the pressure, you don't have leaks. Also, this will draw out any humidity and air from the system. After check is complete, unhook vacuum pump and proceed with charging.

 

Thanks guys... I've gotta go to LA tomorrow for business for a few days... right where I am going someone is selling this all new still in box for $70... seems like a no brainer even if only for one use, not high quality but comes with r12 adaptors and should work for what i need to do right, will start the project when I return from LA

 

You will also need adapter to fit r12 gauges. Odd size schrader
https://www.corvetteforum.com/forums...2-ac-help.html

 

his post says it has the R12 adaptors and will do both... my problem will be getting on the plane

 

If you bypass the pressure switch and the compressor turns on, just shut the car down and take it to someone who already has all the equipment and can vacuum the system down to check it for leaks. If no leaks, have it charged and be happy!

 

You might get some funny looks with these gauges in your carry on. In that case UPS is your friend and send them to yourself. First thing should be to check if you have freon. If that is low nothing else will work properly.

 

Thanks Kanvasman, I fly out later today and gonna talk with TSA... not worried about fitting the items in a travel bag but getting pump through is my concern... already looked into alternative pump resources and gonna call a few local auto parts stores today for rental... I just always think if I'm gonna rent can I purchase for around the same money and have the equipment.

I plan to check static pressures... at this point its all asumption but I am assuming pressure is low though there is pressure on both sides... I also plan on seeing what kind of vacuum is held before moving forward. Thanks again

 

Since you have no idea about the history or condition of the system, I would suggest:

1. Apply 12 V directly to the compressor clutch, after pulling it's connector. Engine off. Just to verify the clutch works. Then take belt off or loosen, engage clutch and rotate compressor by hand to ensure it turns, and is not seized.
2. Check the static pressure. Measure the temperature. Compare to pressure charts online for R-12. If you have ~50-80 psi at least you have some Freon and the system may not be leaking. If it is gas-tight go to step #11 and add freon. If it is zero psi you have both air & humidity in the system, and have leaks. Continue.
3. Attach vacuum pump, and run. Close valve. System should hold vacuum for 30 min. If not you have leaks and are not gas-tight.
4. It will be difficult to identify which o-rings are leaking. They dry out with age. Just open system and change them all.
5. If you open the system, you will need to change out the reciever/drier/dessicant. It absorbs moisture and if your system has had no psi for a while it absorbs humidity and becomes useless. Important: add the drier after the system holds vacuum, you can "kill" the dessicant in it while leak finding / repairing.
6. If you have to change drier, make sure you add the correct amount of the correct oil.
7. Also find, check and change the orifice, if it has one. If that screen on the orifice is filthy like the above pic, you need a complete system flush & clean. Early C3s do use an orifice they use a POA valve. Not sure if/when that changed.
8. Run vacuum test again and verify system holds vacuum again for 30 min.
9. If still leaking, add a can of freon with UV dye. That may help you find the leaks. UV light & goggles. Fix all leaks until it holds vacuum. Make sure adding the new dessicant / drier is the last part you change so do that after the system is gas-tight and holds vacuum.
10. If the system was open to the air for more than a couple minutes, I would pull and hold vacuum for at least an hour, to suck as much moisture out as possible.
11. Once it holds a vacuum, and you pulled your final long vacuum, then you can add your freon, with your gauges. When you attach the gauges, purge the air out of the hoses with a quick turn of the fitting at the valve head until freon hisses out. Be careful to not break the vacuum yet, or re-pull it. Then open the hoses to the system at the valve head and the quick connects.
12. Engine off. Add about one can, valve up so you add gas, until it stops hissing the can gets warm, the psis stop rising, and the can feels empty when you shake it.
13. If you are now at the correct static psi for your temp the ac compressor should engage if you start the car and turn it on. No need to jump the compressor or anything special. If not you have electrical issues.
14. Add a big fan in front of the radiator to make the AC work very well before you test temps.
15. Start the engine, and add the rest of your freon with the engine running. Try hard to add exactly the amount called for in factory manuals, or possibly on the underhood sticker. Add freon to the low side. Valve up on can, so you add gas. +/- a few ounces is acceptable. A couple extra is better than a couple light.
16. Test vent temps with a thermometer.
17. If they are not cold now, you need professional help. Under 50* is OK. 40-45* is better.
18. I encourage anyone to run the vacuum tests, and make the mechanical repairs yourself. Even if you are not confident to charge it. Then take it to a professional for the charge. You can save a lot of money by fixing the mechanical repairs yourself, until it is gas-tight.

 

thanks leigh1322
this is pretty much exactly what im planning on doing in step, been doing allot of reading and pretty much follows what you wrote... as far as needing "professional help" I probably need that anyway 😉