Well at the risk of jinxing my repair it may be safe enough to post this now.

Looks like I have a successful AC repair and upgrade completed. Had to replace a leaking evaporator, which includes the orifice tube, and I replaced the accumulator and all new o-rings. Upgraded to R134a as well.

It was time consuming job much like the heater core but not nearly as much of a PITA since your not having to work in a cramped area. The actual job itself was fairly easy. In summary removed the front wheel, wheel liner, fender, surge tank, washer fluid tank, and brace. Drained the coolant and disconnected the heater hoses and hoses to surge tank. At that point you have straight-on clear access. About a half dozen 10mm bolts (or hex head screws- terminology) and the passenger side half of the evaporator housing comes right off. Cleaned everything up including the nasty fan cage (it was almost black with caked dirt, its now white again!). Picked up the black textured sealant material that seals all the openings where pipes come through the housing (same stuff as the manufacture uses). Re-installed everything and added the 134a fittings.

Charging was a slight challenge after the first can with a C68 AC system you have to jumper the high pressure sensor to get the compressor to cycle on (after you clear the 09 code). Then it sucked in the required refrigerant and oil (about 80% of R12).

And it seems to get fairly cold too. Matter of fact the Vette was sitting at work this morning temps outside about 86°F, and with the cabin temp set at 66° it was at cabin temp within a couple miles and kept it cold.

Dealer wanted well over 1200. for the job, and I doubt they would have taken everything apart and cleaned it before reinstallation, and my cost was somewhere under 250. for parts and refrigerant.

Nice benefit, now the air inside smells nice and clean.

Now for the nose R&R next weekend. All materials are ready just waiting for time to get at it.

 

What did you fly F4-U's?

 

No commercial birds.... why? I'm confused?

 

Oh you mean jinxing... LOL no it didn't jinx port or starboard!

 

Congrats! Gotta be gratifying.

But couldn't you have waited 'til Spring to tell us? That's rubbing salt into the wounds for those of us who remain marooned on this glacier. 86*F outdoors? Must be nice. Sn*wing here this AM. Grr...

Be well,

SJW

 

Sounds like you did a great job. Please give us the same level of detail when you fix the nose of the car

 

Well done!
Nothing like a successful repair done yourself.

Larry
code5coupe

 

Thanks ya'll... considering I knew squat about AC systems two weeks ago I'm fairly happy with my performance. It's kind of a challenge sometimes, can't let the fiberglazz machine beat me. I figure my mechanical aptitude is sufficient for most jobs. Not that I want to repeat it again, but after you've been in there once, the next time will be a breeze. (ha no pun intended)

I photo-documented it, maybe someday I write up something on this.

 

How much did the evaporator cost? Broke mine last week, moving the hose around. I will be doing the same thing in the next few weeks.

 

$174. comes with a new orifice tube.

 

Wow, nice job! You didn't mention the compressor ... does the stock R12 compressor work with R134a?

Gary

 

my AC doesn't work either... don't know what's broken... its not a leak... just something not working.
I wanted to try to fix it myself but seems very complicated... I'm a very novice mechanic

 

Yes. Since the compressor has had R12 run through it, a chemical reaction occurs in which the internals of the compressor are coated with a metal chloride which acts as an anti-wear agent.

To truly improve performance a 134a condenser which is larger should be used. Note to that anytime the system is opened and exposed the accumulator should be replaced.

That said if you have all good working parts, you can take it down and have the R12+oil evacuated, system is never opened up. Then pick up a conversion kit which is about $30. It comes with new adapters, caps and label. The 3 cans contain each 12oz 134a, 3 oz ester oil, sealers and anti-wear agents. When you charge the system your only going to fill it to 80-85% of the R12 capacity. This is because of the higher compression of the R134a over the R12. For example this 93 vette system holds 2.25 lbs or about 36 oz's, 85% is about 30 oz which is about 2 and a half cans. Because your not filling to 100% so the system operates fairly normal.

If you have marginal parts you might push them to an earlier failure. But hey they were going to fail anyway and now get a 134 compliant one when it's time to replace. The accumulator was the same for a range of year models and the desiccant inside is compatible with 134a. Plus now you can go to the parts store and pick up a recharge kit. Replace your component(s), pour in the required amt of ester oil, and recharge. (You have to do a little math as the require amt assumes the refrigerant is not combined with oil, so you use less.) There are different combinations, you can get just a can of 134, can of compressed oil, can of sealers, or get a combo can. There are different oils PAG and ester. PAG is a hyrogenic (spelling) which means it absorbs moisture often causing damage to o-rings and seals. Ester doesn't do that. Most of the combo cans contain ester oil.

Like I mentioned you if it is the electronic air and you have a code set for low freon 09, you have to clear it first by removing the battery negative for a couple minutes. Then jumper the high pressure sensor to command the compressor on. There is a procedure to get to that point though. The key to it all is proper pressure. A good charge is some where between 25psi and 45 psi, area marked in blue on the gage.

All in all, I'm sure there is some info I stated here that will be debated. But this is what I've learned over the last couple of weeks in preparation to work on the system.

Oh one other thing to mention is that R134a is molecularly smaller than R12 therefore more prone to leak easier. Some say it will leak out the hoses if they are old or worn, as well as all the o-rings. I replaced all my seals and o-rings to prevent unwanted leakage. Plus the cans have sealants in them hopefully to help prevent some of the known leakage areas in hoses and such.

 

I have some questions and you seem to really know what you're doing despite your modesty. I bought a 92 in November and when I got it the A/C seemed to work but not very well. I assumed a 92 might be low on freon. Anyway I though I would convert it to 134a and bought a conversion kit. I installed the adapters to be able to put the gage included in the kit on a guess what I have around 40psi. I started the car and turned the A/C on high and the compressor does not engage. Looking at your posts I see that you mention jumping a sensor to get it to kick on. What sensor? The one on the A/C line up near the firewall? I also had the heating and air control blink at me a few months ago so there might be a code that needs resetting. I didn't blink today. Also it's cold here today could there be a sensor to not engage the compressor on cold days? I did pull the A/C fuse to reset it instead of disconnecting the battery. I see in the manual it says to check the fuse and relay and I still have to find the relay. Any ideas or hints?

 

Since you mentioned blinking sounds like you have the C68 Electronic AC. Yes once the low freon code is set the compressor will not activate again unless you clear the code.

You mentioned reading the pressure with the system off? What did it read when the engine was idling, without opening the can tap?

The sensor is located on the large pipe going in the evaporator housing. There are two pipes, one very large and one small one. The small one also houses the orifice tube. Just before the mating connectors you'll see the sensor. The upper sensor should have a brownish colored plastic lock securing the connector. It has two wires going into it. Green and something can't remember I'll check and verify.

Picture of sensor and lock clip:





To read the codes, press both up and down fan speed buttons until --- is displayed. Then press the AUTO button between the fan buttons to display codes. If you are low on freon it will display and 09 code.

To clear the code, remove the battery negative ground cable for about 2-3 minutes.

To bypass the sensor, disconnect the electrical connector at the sensor. It has a brownish color connector lock that must be removed first. Examine the connector closely and you'll see where you press in to release the brown lock. Then press and pull on the electrical connector to remove it. Insert a normal size paper clip to jump both pins of the female side of the connector. Make sure it doesn't touch anything metal.

With the battery now connected, turn the Ign On and set the AC to OFF. Connect your 134 system up. Start the engine and let it idle for a few minutes to clear the lines. Assuming there is some charge in there otherwise if it is completely empty try to get one can into the system before engaging the compressor. That's the tuff part. Otherwise, set the AC to MAX, high fan speed and set the temp down low say 60-65. Open the tap on the can fully. Start shaking the can and it should start sucking in the 134. You want the pressure to be more about mid way of the blue area or about 30-35psi. That should give you about an 80% fill.

Although summer is not here yet, people say 134a is not that great, but mine is doing a very good job of freezing me out.

After you get about 2.5 cans in. It should be full for a 134a fill. Be careful about running the compressor with no freon or oil. Damage can occur, so if it is not taking the freon at this point you may have to look at other issues.

Always observe all warnings.

After it is completely charged, then shut the system down. Remove the jumper and re-connect the high pressure sensor. Start it up and verify the system is operating normally.

 

Yes I have the electronic A/C controls.

Car off or running the system read 40psi, but I never got the compressor to turn on so it would make sense it's the same.

I just got back from the doctor so I'll try working on it again tommorow, supposed to be a very nice day here. Thanks for the help. I appreciate it.

 

Also, you may read from time to time people say warming the can will help move the refrigerant. I would NOT recommend this. This is very risky and can cause physical harm or worst. At best if you want you can put your hands around the can but that would be as far as I would go.

 

Jet-Jock, I sent you an e-mail...

 

Looks like I got it done, the only problem was the instructions and cans said to hold them upright when filling and they needed to be upside down. I think most of the first can was wasted because of that. I ended up with a little less than 35psi running and when the a/c is off it goes up to 55psi.

Thanks!!

 

I hope you're satisfied with R134a. I ran it for about a month, then went back to R12. The new stuff just didn't get cold enough, but I live in a high humidity area.

BTW, congrats on doing the job yourself. It feels good, don't it?