Supernaut72

After a lot of sitting around daydreaming about it, I'm finally getting my '67 Delta's AC system back up and running. The rubber lines are currently out to get rebuilt. Foolishly, I'd taken the advice of a shop I consulted with and re-used them, and while the system held vacuum perfectly for a week, it did weep oil and my cheapo HC test refrigerant from the hoses during my pressure test with some underhood heat built up.

I'd waited until I was about to test-charge the system to install the new drier, and after bleeding off a bunch of pressure the system came to rest with a positive pressure of 40 PSI, which it stayed at for two full months until today. When disconnecting the lines to take them in today, I went for the discharge line->condenser and drier->line to TXV connections first and wrapped them tightly in a couple layers of plastic wrap secured with tape. I think I've done a pretty good job exposing the drier to open air/moisture as little as humanly possible, both today and previously.

Anyways, what I wanted to know is, how hard is it to kill a new drier? I think the CSM says it has to be replaced if it's been left open and uncapped for 24 hours total, assuming my tight plastic seal job is sufficient then it's been exposed to air for nowhere near that. Probably five or ten minutes tops, mostly while wrestling the condenser side of it into position during installation.

Fun71

You're in Tucson where the humidity is very low and the exposure time was minimal. I would pull a strong vacuum after the system is assembled and not worry about it.

Here's something to ponder. How well was that new drier sealed before you purchased it, how long did it sit on a shelf somewhere after it was manufactured, and what was its storage environment? The conditions you exposed it to may be benign compared to what it saw before you purchased it.

Supernaut72

Good point. Guess I've just been influenced by all the posts on the internet by fear-mongering "certified AC technician" types who forecast massive internal corrosion problems and system failure if *any* moisture is present in the system. Probably a result of the R-134a era, what with the new oils that form acids when exposed to moisture.
...Not that that's really my concern, since I've sworn off R-134. I'm just trying to do my best not to have crappy cooling after all this effort.

Regarding the drier, it definitely did have a pressure differential when I originally unsealed it, so the seals were good... But it's always possible that great care wasn't taken where it was manufactured, prior to sealing it up. I'll stop worrying about it.

budg

If you are uncertain about it and the drier isn't that expensive , I would replace it.
Better to be safe than sorry. As far as the moisture aspect , the worse that can happen is the drier gets plugged up and doesn't allow refrigerant to pass, or won't allow it to pass freely enough. The filter drier is filled with a desiccant that absorbs moisture. Once it is saturated with moisture it will cause a pressure drop and your ac system will quit cooling. This comes from an AC tech with 20 years in the business working on commercial and industrial systems.
Hope this helps.

Ozzie

I tend to agree with Kenneth. There will always be a bit of environmental exposure during assembly. Tucson's air should do less damage than most. Try to use a two stage pump and try to assure a moistened shaft seal on the compressor. Run the pump until there is no evidence of it removing anything and complete the charging. You will likely have no problems. But if it will upset your sleep, replace the drier.

Supernaut72

I decided it wasn't worth fussing over too much and kept the drier, since I truly have been very careful about atmospheric exposure (plus, yes, it is generally dry here. 40% humidity is "high" for us, though it occasionally spiked far higher now and then while I was doing a lot of this work, more like 80%). So far, so good. Thanks, guys!

classicmuscle442

The best way to evacuate a system is do a triple evacuation. Good shop should have a micron gauge to be certain it is dry as possible. 400 microns is best and will pull moisture from drier.

Supernaut72

Good tip, ideally that'd be the way to go. As it happened, I wound up doing the vac myself, since I ran over-budget after I stumbled across a deal up in Phoenix for more R-12 than I needed. Way too good to pass up. A 12-pack of virgin 14 oz Igloo cans for $180, much cheaper per lb than any local deals I've come across. Still had the sticker from K-Mart, dated 1985. Cool find just for the fact that the case survived along with all the cans.

Right now I'm just waiting for warmer weather to run some real tests on the system, the last results I got at 86*F and 20% RH were impressive though. 40* at the vent on fresh air at a dead idle, CSM calls for 43 +/- 2* while running the engine at 2,000 RPM. I've run the system below that, to test out the insulation job I did on the rubber suction and liquid lines to prevent them from absorbing or re-absorbing as much engine bay heat (the idea being to keep head pressures down a little in hot weather). Suction line's metal bits frost up real well.

I did notice bubbling in the sight glass while using the system to help dehumidify the interior today (slightly leaky rear glass, interior gets musty after it rains), though it was 60* out. System was stabilized, had been running for 10 minutes or so. I've heard that sight glass bubbling may occur below 80* ambients or so, so now I'm waiting on warmer weather to confirm whether this is the case. New double-lip shaft seal is definitely a recommended upgrade, no oil slinging after perhaps six hours of operation, more than I can say for the reman w/ mechanical seal that I put in my Chevy.

Ozzie

Normally you would watch ambient temperature & humidity, duct discharge temperature, high & low side pressures, weight of charge, compressor RPM, and the sight glass, and try to hit it as close as possible to the manufacturer's specifications. Usually everything is not satisfied. Since your system is modified the manufacturer's numbers mean less than usual. Due to the frailties of the system you will likely find yourself needing to "top off" the charge from time to time. (Try not to introduce air into the system when doing this.) You'll get a lot of ideas on your question, but to keep it short, if the charge weight and gauge pressures are "reasonable" I'd probably add about 1/4 pound after clearing the sight glass. Sometime trying to save a partially used "tapped" refrigerant can will be as rewarding as urinating into the wind.

Supernaut72

Argh, edited my post to be less wordy-wordington, and to be a little more clear. Oops. Sorry about that. But yes, it's satisfying all the numbers effortlessly. I agree about trying to keep a tapped can from leaking out, it was fighting me tooth and nail while charging the system, had to keep the can tap clamped super tight to stop it from seeping. If I do need to top off, I have a short-filled one set aside. Only 11 oz while all the others have between 13.8 and 14.1 oz, accounting for an even 3 oz per empty can.

The system has all new o-rings, the only ones that haven't been done are the compressor's body seals, since there's a new double-lip seal in there and I realized that the shaft threads would probably destroy it if I pulled the compressor apart. Plus the compressor had held in earlier testing, so I figured why try to fix what isn't broken, and risk winding up with a freshly re-sealed compressor that doesn't seal. Oh, and the expansion valve outlet to evaporator o-ring... Forgot about that one until it was too late.

Fortunately the old o-rings I've pulled out and replaced have all been very pliable and healthy, so it looks like despite this car's horrible neglect the AC system held together pretty well.

Supernaut72

RE the bubbles in the sight glass in 60* weather, I've now seen a couple posts by member "NickD" over at the auto AC forums explaining that if the sight glass is clear at normal AC weather temperatures and with the idle raised to the proper testing/charging speed provided in the manual, it can have bubbles at idle under the right conditions, and will have bubbles in cold weather, with a warning not to try charging a system at idle or if it's not at least 80* out, with potential severe overcharge being the result (I did mine on an 86* day but those are few and far between at this time of the year). Didn't know that.

Guess it's fortunate I'm so hesitant on stuff like this, if I'd pulled the trigger on adding that short-fill can then I'd probably come out way overcharged come warmer weather.

So I suppose as long as it continues cooling as well as it has been in all my tests, I'll just leave it be and move on to my next project, which will likely be re-soldering my 4-row Spectra copper radiator, since all the radiator shops I've contacted "don't fix radiators anymore". Radiator cools fine but the joint between the driver's side tank and the core is now weeping coolant, after a whopping 5,000 miles. Woohoo, quality parts.

Ozzie

Usually once an O-ring seal gets made properly it will stay tight as long as it isn't "messed with". As long as the refrigerant isn't leaking through the walls of the hoses the primary loss is through the compressor's shaft seal especially when it's oil coating disperses. In the winter try to run it at idle for a few minutes every couple of weeks to re-moisten the seal.

Supernaut72

Very true. The system held vacuum at the same level for a solid week, and then held pressure during an earlier Duracool test with mostly original O-rings, I was impressed. Only parts that gave out were the old rubber hose segments, which couldn't even contain static pressure. All those other new O-rings were probably overkill, I suppose.

I remember seeing an old decal from an earlier AC car (a Plymouth, I think) instructing the owner to run the air conditioning at least 5 minutes every two weeks, sure is good advice.

classicmuscle442

Regardless of outside temperature, vapor charge till lowest supply duct temperature. When supply air temperature starts rising stop charging. Best with digital thermometer.

Supernaut72

If the bubbles persist when it warms back up or the vent temps start to stray off the mark when it reaches 90, I'll take that to mean that I under-charged a little and will get the equipment back out to finish up the job with that method, since I agree that's a great way to fine-tune the charge during/after filling by weight. Until then, I guess I'll just stop fussing with it since days that call for AC use are few and far between at this time of year, even here.

What especially makes me want to hold off for now is the fact that I'm only working with a can tap instead of a cylinder, so unless I'm a full 11 oz low, I'll be wasting a good amount of refrigerant after puncturing the can. If I find out I need to add more once the weather heats up, I might be able to donate the leftovers in the can to a friend who's going to be overhauling his Camaro's AC soon, instead of letting it all slowly escape.

My2nd 69 442

Supernaut72, Where did you have your system serviced. I also live in Tucson(east side) and I need to have my R 12 system on my 69 442 serviced. I've rebuilt my A6 compressor, Had my hoses rebuilt and replaced my dryer.