My AC Rebuild Project

[presslab]

[LynnsABCs]

I've got a 2 hp compressor and I agree that the target 29 hg number is better. This was just a first run to see if the system will hold vacumn.

Happy to report that this morning, I had no loss of vacumn. Will be running a longer suck down before I charge the system and plan on taking photos.
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[hiram6]

I want to jump back a few posts and ask a question if I may. I'm a few steps behind the OP in my own AC rebuild. I'm at the point of installing a brand new compressor, ordered from our friends at Southeast Air. It arrived sealed with some plastic plugs over the pressure and suction ports, and a few ounces of clear oil (I'm assumed Ester) behind those caps.

I followed the advice I found somewhere else on the forum (not this thread) and drained that clear oil out into a measuring cup, added ester oil from a new bottle up to the recommended preload of ester, IIRC, I only added a couple of ounces to the drained oil to get the total recommended by the Bentley. I also added Ester into the other components of the system as specified by the Bentley.

If I'm reading what you guys did correctly, I should not have re-used the clear oil that was in the compressor, right? If I need to change out my ester oil, no big deal, I'll do that.

Now, question 2. But what about the compressor oil itself? Am I correct in thinking that there is internal lubrication oil in the compressor itself, seperate from the ester oil in the system? Does that need to be drained and refilled on a new compressor?

I'm hoping to hook up my little Harbor Freight venturi vacuum device over the weekend to see how tight or leaky my system is after replacing the o-rings, expansion valve, drier, and blowing out all of my lines. Good advice on taking it to someone to pull a stronger vacuum afterward.
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1985 Westy, 1.9L automatic (Daisy)
1996 Mazda Miata
1998 Jeep Grand Cherokee 5.9 Limited

You can't lie around on the beach and drink rum all day.................unless you start first thing in the morning.

[LynnsABCs]

The tech at Southeast Air told me to drain and fill with 8 oz of oil. I used the same Ester for the compressor and some for the suction side hose. If you take off one of the screw on caps and rubber stopper and tilt the compressor, the oil comes out that fitting, so I'm assuming the oil can move throughout the system.
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[pushkick]

so what is the make and model number of your new compressor ? the original compressor in my 1990 van is a sanden sd709 model 7411.
when i looked at several web sites that sell compressors and the sanden site they suggest changing to a sanden sd7h15 model 7411. this is a 7 piston and 15 cc compressor.

[LynnsABCs]

Well I was wrong on the vacumn reading. I only have 20 hg.

I can spend $150 to buy a better vacumn pump on ebay or take it to a pro and have them pull a lower vacumn to 29. I'm trying to decide if it makes more sense to have the pro go ahead and charge with 134A at this point. If the system needs to be evacuated for some repair reason later, a shop won't evac the Redtec and I don't want to release it into the air.

I'm doubtful a shop would be willing to pull the vacumn and not also charge it. Any ideas?

Here are some photos of the gauges and vacumn pump hooked up.

Before I can charge the system, I have to repair both drain tubes on the drain pan. Both were broken when I removed the evaporator cover box.

Van Cafe lists a repair part but it comes in 3 sizes--small, med and large.
Why wouldn't a piece of rubber tubing glued to the end of the pan and stuck into the drain hose work?

Last step is to get my son to help me hoist the evaporator box cover in place--not a one man job.
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[LynnsABCs]

The compressor is a Sanden 7411A and was $245 + 16.06 shipping. Total $261.06.
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[James 93SLC]

I believe I saw a proper vacuum pump in the latest Harbor Freight ad for $89. I would go that route instead.
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91 Vanagon Carat
93 Corrado SLC
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Photos: http://picasaweb.google.com/slc.corrado
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tencentlife "Sometimes a pooka is a problem and sometimes it's just a pooka"

[pete000]

How long after you pull the vacuum do you need to charge the system?
My system has been empty for a while now. I was going to buy one of those HF vacuum pumps and check my system for leak down.
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1990 Vanagon RS 2.1
1967 Deluxe 21 window
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Koni Shocks
H & R Red Springs
Addco Sway Bars Front-Rear
18 X 7.5 and 18 X 8 OEM Porsche Wheels
Recaro Power-Heated seats

[MarkWard]

I am sorry, but from the picture, it looks like the needle stop is before 30 inches of vacumn and the needle appears to be on the stop. That is odd for a set of AC guages. You could be pulling more vacumn, but the guage won't measure it. The screw in the bezel is for zeroing the needle. Where does the needle zero now? You might be able to add some to zero to see how much vacumn you can actually pull. We'd have no problem pulling a vacumn for someone without charging. Regards

edit: A rubber hose could be glued as long as it sealed. There is no pressure there. The nipple just gave the drain hose support and probably sped up the install time. On the assembly line, no one could sit there an hold it while the glue dried.
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[LynnsABCs]

Pete. The word from this list is pull a vacuum to 29 hg and it should hold that level overnight.

I called the independant foreign car repair guy I use and he quoted me $250 to pull a hard vacuum and recharge with r134a and $400-500 to use R12.

The local Harbor Freight has the vacuum pump. Their model number is 98076. It is rated at 2.5 CFM. The building super in my office building (fixes all the AC units) said 2 CFM is adequate, so this should do the job. $89.95 as mentioned earlier.

My son is taking me to Atlanta to hear Paul McCartney for my birthday so no work this weekend.

Anyone know about repairing the drain pan drain fittings?
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[presslab]

[hiram6]

Home Depot sells a two part epoxy that is specially formulated for plastics. I have has relatively good success with this as long as what I'm glueing is 100% clean!! I use isopropyl alcohol wipes, seems to work well. AFter the epoxy sets up, it's not very flexible, so you would need to make sure you've got it where you wnat it. There's no flexing it later
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1985 Westy, 1.9L automatic (Daisy)
1996 Mazda Miata
1998 Jeep Grand Cherokee 5.9 Limited

You can't lie around on the beach and drink rum all day.................unless you start first thing in the morning.

[Alaric.H]

I asked a guy about vacuum and he sent me this.

http://docs.google.com/gview?a=v&pid=gmail&...tion%2Fpdf

[furrylittleotter]

Without getting overly complicated Refrigerant changes its structure (Gas liquid, etc.) throughout the A.C. system. The refrigerant oil mingles with the refrigerant in its various forms and travels throughout the system accumulating in various areas throughout the entire system. While some does, It does not ALL just lay in the compressor like an engine crankcase, which is why it supposedly takes quite a bit of oil to lubricate the relatively large Vanagon system. (there is a lot of area inside the entire system for it to accumulate)

I would recommend vacuum testing initially, then follow up with an overnight (or longer ideally) PRESSURE test. 80 psi should be adequate.

Seals like the one on the compressor shaft react differently to vacuum as opposed to pressure. Then I would have the system professionally pumped down and the refrigerant weighed in.
Barring that (we are do-it-ourselfers aren't we?) I would pump the system down (vacuum it) using a new or never-been-used-on-other-than-134a Vacuum pump in good condition capable of pulling 10 microns, (peg your in. gauge)

C.F.M is the RATE at which a vacuum pump pumps, whoever told you that 2 cfm is fine should probably not be trusted with technical information. It is fine but it is a moot point, there are a myriad of other factors that are far more relevant and important. .1cfm is adequate if you let it run overnight, and 5 cfm is too small if you only run it 5 minutes...I probably should not be so blunt, forgive me, I do not know the exact question you asked and the context, but many A.C. tech.s simply go through the motions without understanding the reason they are doing so.

The FAR more important factors are quantity of vacuum, time held, relative humidity, material being vacuumed, etc.

I would either leave the pump on overnight to allow all the vapor that has been absorbed into your POROUS (hard to believe, I know) aluminum coils, hoses, fittings, o-rings and unsealed compressor (caps don't keep vapor out) to flash out, or use a hair dryer to warm all the accessible coils, hoses, etc. to facilitate the process.

(Note the previously posted chart. It has points for temperature and vacuum, therefore if you want to facilitate the removal of vapor, raise the temperature to flash the vapor.)

The vapor will exit the vacuum pump exhaust (slowly) some will be embedded in the vacuum pump oil until the pump gets it own oil hot enough to flash off the vapor so ALWAYS let your pump get very hot while using it or valve it off and let it run for an hour after using it, the alternative being to change the oil after every use. Yes, I'm serious. (it doesn't hold much and it's cheap)

Then, valve off the system and fill into the low pressure side using known quantities of refrigerant in vapor form and extremely small blasts of liquid. (turn the can quickly once every minute).

Don't forget to purge the air out of the gauge set with refrigerant! crack the connection from the line going to the can where it meets the gauge set with the can open and vent that to atmosphere a few seconds to empty the line of vapor filled atmospheric pressure (air), do this with every can unless you can valve off at can every time.

I like the idea of adding the oil through out the system and think it sounds great to do so, I guess one would do this just before the final vacuum stage.

You have already saved yourself enough to buy a real set of gauges and a vacuum pump sir, and I would highly recommend it, especially if you intend to do that Porsche. A good pump is only $300 at Grainger. While you are at it do the world a favor and smash that set of gauges you bought before someone gets hurt.

[LynnsABCs]

Sorry for the long delay. Too many projects and car shows got in the way.

I bought the $100 AC pump thing at Harbor Freight and pulled the vacumn to 30 for about 30 minutes and it held that vacumn over the weekend. I've decided to sell the vanagon and am waiting to recharge the system as the purchaser may prefer it be charged with r34 instead of RedTek.
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LynnsABCs
Knoxville, Tn
1990 Vanagon Westy
1961 Porsche 356 B Notchback Coupe

[campism]

"Anyone know about repairing the drain pan drain fittings?"

I'm a fan of the "sleeve" method of fixing stuff like this. For a different type broken plastic tube repair I went to a hobby shop and found a length of metal tubing (brass or aluminum is usually available) of the correct diameter to fit inside the broken tube and very thin-walled so it flows adequately (probably not a big deal in this application). I cut this to length and tested the fit then used JB Weld to hold the whole thing together, coating the outside of the metal length and assembling with the excess goop smoothed at the joint and where the tube exits the drain pan.