Guidance on AC repair path

[Terry Kay]

The reason that oil is induced into the lines of the system is because the crankcase of the compressor & the lines are not shared.
The oil in the crankcase is separate form the oil in the lines & the head of the compressor.

I would wash ot the crankcase with the air dryer alcohol.
A couple of times to make sure whatever that red stuff is, is outa there.
The alcohol will all evaportate outa there pretty quick after your all done--

Load it up with whatever oil your going to use and spin the compressor over by hand, or your drill a couple of times to make sure the oil is on all of the bearing surfaces prior to firing her up again.

You'd be washing the crankcase of that compressor out using oil for a month before you got all of that who-know's-what kinda oil outa there.

Sounds like you've isolated that leak--that's good.
_________________
T.K.

[mbwesty]

[denwood]

One thing I was a bit flipped out about is adding 5 oz to the Sanden 709 compressor in my van, then in diagnosing the AC, pulling the compressor to only find a small amount inside when dumping it. I did some research to make sure something weird wasn't going on with my compressor.

Watch this.


Link


Then watch this. There is no fill port on this compressor..you add your 7 ounces to the back end of the compressor and circulate it by hand spinning the pump.


Link


He adds oil to the compressor and then explains how only an ounce or so (of the 6 that they add) stays in the compressor..the rest is circulated in the system. My conclusion is that the oil you add to the Sanden compressors system ends up circulating in a fairly even fashion throughout the entire system in suspension.

This article in 2003 discusses the fact that modern compressors do not have oil sumps but rely on circulated oil in the refrigerant. Again here, they discuss oil sumps in older compressors and refer to the Sandens as piston pumps with no sump.

http://www.nostalgicairparts.com/ac/compressors-1.php

This would suggest running your compressor when low side pressures are too low is a good way to kill it as a result of oil starvation...cuz there isn't a whole lot sitting in the compressor during operation. Just over an ounce if the information is correct. This is pretty much what I saw in my explorations this week.

Cheers,
Dennis.
_________________
Cheers,
Dennis Wood
The Grape

[denwood]

From Sanden themselves: http://www.sanden.com/originals/images/compressor_installation_instructions.pdf

If you're replacing a compressor from a system that has not been flushed..they are advising to drain the new compressor drain the old compressor...and only add to the new, the amount drained from the old. I believe Terry Kay has made the same recommendation the redtek thread.

I assumed that as Bentley calls for 5 oz in the fill plug, then that is what you would expect to drain out...not true.
_________________
Cheers,
Dennis Wood
The Grape

[mbwesty]

<<One thing I was a bit flipped out about is adding 5 oz to the Sanden 709 compressor in my van, then in diagnosing the AC, pulling the compressor to only find a small amount inside when dumping it.>>

Where you put the 5oz? In the crankcase or in the head? Sure, if 5 oz was in the head then one should expect the oil being circulated in the system. As evidence I am finding oil in the condenser and the lines.

<<My conclusion is that the oil you add to the Sanden compressors system ends up circulating in a fairly even fashion throughout the entire system in suspension.>>

Sure, from what I have read the oil in the head get circulated but the oil in the crankcase remains there for lubrication. Am I wrong on this?


<<This would suggest running your compressor when low side pressures are too low is a good way to kill it as a result of oil starvation...cuz there isn't a whole lot sitting in the compressor during operation. >>

For modern compressor? As my very old Sanden SD 709 has oil in the case at all time and oil in the head being circulated?


I couldn't be more stoked today I thought of Vellios in Lawndale and took my condenser there the old timers there said they should be able to weld the hole shut...for $20!!!

I hope it works...scored!!!

[Terry Kay]

The air compressor sump, or crankcase should have oil in it---it has a capacity , and does not / should not/ will not mix with the oil in the lines.

if you have too much oil in the lines it will / could cause the compressor to stall, and not operate properly.

You can also jazz up the reed valves in the head real quick.

The oil in the lines is miniscule compared to the oil in the compressor's crankcase--at best.

This is the way it was intended, and the way it always should be.
_________________
T.K.

[denwood]

Terry, this Sanden manual, covering the Sd709 is very clear. The sd709 does not have a sump. http://www.sanden.com/originals/images/SD_Service_Guide_Rev.2.pdf

From the manual:

6.8.1 Oil Flow Theory
• Compressor lubrication occurs as the oil which circulates with the refrigerant passes through the compressor crankcase during operation. The Sanden SD series compressor achieves optimal durability and cooling performance when oil circulates through the system at a ratio of 3.3% to 8% oil to refrigerant. Excess oil can act as an insulator limiting heat transfer in the evaporator and condenser, while too little oil can negatively affect durability.
• Oil will collect in low pressure cool components (evaporator, accumulator and suction hose) of the refrigerant loop. For example a long suction hose which sags can collect several ounces thus reducing overall oil circulation ratio.

6psi on the low side is their threshold..due to oil starvation I'm guessing. Also, this is definitive:

11.The amount of oil in the compressor after running for 10- 15 minutes should be as per the table at right. Determine from the table what the correct amount of oil should be for the particular speed used in step 3. (The table shown applies to SD5H14 and SD7H15 compressors. It is important that a quantity of oil remains in the crankcase. (these compressors wobble cylinder pumps like sd709).

Compressor RPM
Oil In Compressor fl oz

1,000
3

2,000
2.5

3.000
1.7

4,000
1.3

5,000
1.2

So at 4000 rpm, ( compressor) only 1.3 ounces in compressor. if you were to shut down the immediately after 4000 rpm, I would expect only 1.3 ounces in the compressor crank/heads, plus the .5 ounces they suggest is left behind coating internals.

Based on this manual, adding oil to the compressor using the add port likely ensures a well oiled compressor on start up, however the oil circulation section posted above is very clear. From the rep video above, a working compressor will end up with 1-2 ounces of oil in it (including crank case and head) once it has been run for a short time.

Please don't shoot the messenger

cheers,
Dennis.
_________________
Cheers,
Dennis Wood
The Grape

[AndyBees]

Admittedly, I only read the Original Thread Starter Post and a few of the posts that followed.

Anyway, here is what I did to my '84 Vanagon AC system as part of my TDI engine install. I modified the fittings to the Compressor that was on the TDI engine to accept the Vanagon AC hoses unmodified. Next, I replaced the Dryer with a new one that looks exactly like OE but is for R134a. Next, I removed the overhead unit and disassembled it down to the last piece. I carefully taped over the ends of all AC lines for protection. Then, I cleaned everything on the outside......... lots of water , soap and more water and compressed air. I repaired/replaced broken pieces parts to the unit housing. Then, I replaced the Expansion Valve with a known good used one (cleaned it with Carb cleaner and blowed dry with compressed air). Every line fitting that was disassembled got a new O-ring.

I then pulled a vacuum of 30 inches. I left the Manifold gauge connected for three days (this is a project vehicle with the TDI engine). The system held the vacuum! I then install about three ounces of the appropriate oil.....let it sit for 24 hours and then pulled another vacuum. Then I charged it with approximately 2.5 cans of R134a. About a week later I added an "off the shelf" three ounce can of oil and a three ounce can of sealant/leak detector.

I installed a circuit to the dash with a Green LED that comes on when the comprssion kicks on!

The system works great!............excellent cooling! The compressor cycles as expected.

Edit: I did remove the head of the Compressor and removed the variable valve and replaced it with a 9/16 inch bolt. That made it similar in operation as the OE compressor.
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

[Terry Kay]

<<<Terry, this Sanden manual, covering the Sd709 is very clear. The sd709 does not have a sump.>>>

Dennis,

Do some more reading--you stopped way too soon on the infomercial.
Do some more calcutaling, and please read that wrning label on that new compressor as how much oil is to be added to the crankcase of the R-709 prior to firing it up--and don't forget the formula for the length of the suction hose--and the charge that goes along with it--


<<Please don't shoot the messenger >>

No--just read it all--past the RPM info you posted--not all that far away from it--maybe 2-3 more paragraph's

Look at the funnel, look at the plug, read the length of the hose info---read the amount of oil that's supposed to be adde to the compressor using Sanden's formula--before it's fired up.
_________________
T.K.

[Terry Kay]

<<One thing I was a bit flipped out about is adding 5 oz to the Sanden 709 compressor in my van, then in diagnosing the AC, pulling the compressor to only find a small amount inside when dumping it. I did some research to make sure something weird wasn't going on with my compressor.>>

Dennis,
Watch this.
Watch how the guy dumps the oil out of the compressor & loads it up.
He pulled the plug and most of the oil dumps out of the plug hole for the bottom end of the compressor.
Then he loads it up with 6 oz of oil.




Link

_________________
T.K.

[denwood]

He explains that it has six ounces on board because this is the typical full charge for a new system.

The Sanden manual seems very clear..at 4000 rpm for a similar compressor, only 1.3 oz are in the compressor. The way I read this is that if you stop the compressor after it has run for a short time at 4000 rpm, you'd only get 1.3 oz out. If it was running at 1000rpm, then stopped, according to the chart, you would expect to find around 3 oz onboard.

The procedure according to the manual to replace a compressor (where you are not flushing the system) is as follows:

1. Drain the new compressor completely.
2. Drain the old compressor completely.
3. Add back to the new, the volume of oil removed from the old.

My observation after pulling my pump, 1 day after adding 5 oz via the fill port...there was less than 2oz in the pump. This is consistent with the Sanden manual after shutting down an SD series pump after higher rpm operation. My question is..if the Sanden has a crankcase (and they say it does not), why empty a new compressor and re-add the volume taken from the outgoing unit? They're doing this to avoid having too much oil in the system. This makes sense (IMHO) when you consider section 6.8.1 of the Sanden manual:

6.8.1 Oil Flow Theory
• Compressor lubrication occurs as the oil which circulates with the refrigerant passes through the compressor crankcase during operation. The Sanden SD series compressor achieves optimal durability and cooling performance when oil circulates through the system at a ratio of 3.3% to 8% oil to refrigerant.

section 6.8.3 details oil charge for a system taking over 56oz (and we're close on the Vanagon). The procedure is to charge the system, run the system at one of the RPM ranges in the chart, then stop the system. They then want you to evacuate, remove the compressor and drain the oil to see if the amounts correspond the RPM chart. So if you ran at 2000 rpm, you should get 2.0 oz out, add .5 for residual, so 2.5 oz in the compressor. Then you remove or add oil to ensure that the RPM chart level is reached. Personally I think this is nuts...likely less labor to flush the system, then add the total charge for the system to the compressor. The manual states that if the system requires less than 10oz, you can add this to the compressor fill port. If the full system spec'd was 12 oz, you could add 10 to the compressor, and 2 elsewhere. The drain procedure in 6.8.3 step 7 and 8 have you empty the compressor via the drain plug, as well as the suction/pressure ports. To determine compressor charge. If there was a sump and set amount for the compressor, you would simply add the same amount every time. The manual however has two pages of technical information on determining the correct compressor/system charge!

They're not saying the head is lubricated with oil circulating in the refrigerant..they're saying the crankcase is lubed this way.
_________________
Cheers,
Dennis Wood
The Grape

[Terry Kay]

Your overthinking this whole deal.

I don't know if you pulled a new compressor out of a box--or are using your old one & drained it.
If you drained an old one you knew that it had a drain & fill plug.

Load it up with oil, bolt it up, evac the sytem with freon & go.

Don't complicate a pretty simple and straightforward process.

Your reading way too much into this pretty easy job.
_________________
T.K.

[mbwesty]

[Terry Kay]

First question;
Why or better yet, how are you planning on flushing the system out with the condensor not hooked up?
I'd connect it first.

Second & third;
I have mentioned many times in the past , any prominent Truck dealership, repair shop, or parts facility will have cases of the air dryer alcohol in stock.
Common item--as the geeks at the local car parts joints are giving you the goofy looks.
They just don't know any better.

And if your looking for AC specialties, ya gotta get away from the parts grocery stores.
They only have fix a flat, and instant AC repair in pressurized cans.
They don't have a clue ( obviously ) what R-12 is let alone AC mineral oil.
_________________
T.K.

[mbwesty]

[Terry Kay]

Another simple question;
Why would you even consider leaving the condensor out of the loop?

You think--assume the guys at welded it up cleaned it up inside too?

This one is beyond me--
_________________
T.K.

[mbwesty]

[denwood]

MB, the Sanden technical manual suggest PAG ...however I believe this is because they ship new compressors with this onboard.

If you're flushing everything anyway, why not use the Ester100 synthetic? It's R12, and R134 compatible (no danger of crud), and Redtek is standardized on Ester oil.

In other words, there is no danger at all of using the Ester100 in your system (based on my research..and what was in my system for the last 8 years!). If you drain the compresser as per Sanden's procedure (drain at both high/low as well as drain port), then add 8oz Ester100 synthetic to your compressor..done. This is what I did in messing with the system (had pulled the compressor), and during the following evac there was ample evidence of the dye-carrying oil present in the vaccum pump "effluent"

Cheers,
Dennis.
_________________
Cheers,
Dennis Wood
The Grape

[mbwesty]

[denwood]

Mb, my setup was R12, Sanden 709 compressor re-used. It was converted to 134a, and then Ester 100 synthetic (R12 and 134a compatible) was added. Therefore there was mineral in there originally, then converted to 134a with ester100 synthetic added 8 years ago. Aside from the 134a leaking out over 8 years, no issues. The bottle I used looked very similar to the Ester100 synthetic included in the R134a conversion kit sold by Van-cafe.

In flushing the system for Redtek, it was very clean. I just saw solvated oil in the methanol.

Cheers,
Dennis.
_________________
Cheers,
Dennis Wood
The Grape