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Guidance on AC repair path
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Terry Kay
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PostPosted: Mon Aug 13, 2012 2:43 pm    Post subject: Reply with quote

<<Well, I am having problem finding the high pressure port in my 88 Westy. I think the low is near the compressor. Also, as my A/C system has been inoperative since I bought my van 10 years ago, and I really don't have the service records/problems history with the A/C system.>>

The high pressure port is behind the closet shelves.

<<1) Should I say replacing the compressor and drier is a must? >>
The dryer for sure, maybe the compressor.
I would at least service the compressor

<<2) Also, since I have the original service port so I probably should perform a 134 conversion on the system to take Red Tek?>>
No--leave it as it is.

<<3) Should I vacuum or pressure test the entire system for leaks first? And do I do that via the low pressure port?>>

Absolutley Yes---
It requires suction from both ports at the same time.

<<4) The clutch on my compressor is not engaging (or the compressor isn't running when the A/C is on) how can I isolate if the problem is the sensor/power/or the clutch? >>

That's because maybe--the system is out of freon.
The low pressure switch is keeping that from happening.

<<5) How do I test each pressure switches and sensors to see if they are still ok?>>

Load it up with refrigerant---

I think your going to need one of these prior to continuing--
Good reading,,and will answer any & all of your questions on AC theory & operation

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dhaavers
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PostPosted: Mon Aug 13, 2012 2:57 pm    Post subject: Reply with quote

Terry Kay wrote:
...I think your going to need one of these prior to continuing...

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Similar info here (free download):
http://www.ariazone.com/manuals/Automotive%20Air%20Conditioning%20Training%20Manual.pdf

Read it & get busy...
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Terry Kay
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PostPosted: Mon Aug 13, 2012 3:20 pm    Post subject: Reply with quote

Not even close to the Mitchell's Manual. ( & printed the manual for The Snap On Corp.)

It has set the world wide standard of automotive trouble shooting & Training information excellence for many years---

GM used their manuals in AC school--Wonder why?


Who's Ariazone?
Subsiderary of Autozone?
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dhaavers
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PostPosted: Mon Aug 13, 2012 8:56 pm    Post subject: Reply with quote

Terry Kay wrote:
Who's Ariazone?

Just an online auto AC system training manual I came across.
I'm not a pro, but it looks a lot like what I've read in my Mitchell.
Some of it looks better.

Company happens to be in Australia, but that doesn't mean
they know anything about auto AC...

Rolling Eyes

http://www.ariazone.com/index.php
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Terry Kay
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PostPosted: Mon Aug 13, 2012 9:01 pm    Post subject: Reply with quote

The Snap-On Manual ( or Mitchells) that I posted are also period R-12 correct for the Vanagons.
They have the right info of what to expect from the factory R-12 AC system.

If folks are looking for 134-A specific material, than I would expect the Aussie info to be more of what information they might be looking for.

The Mitchells books are easy to read, & comprehend.
It has an excellent trouble shooting guide--bar none.

Again, in my opinion, the soon to be extinct 134 alternative freon mistake would be an error in judgement.
Especially in an antique AC operating system.

The only difference here VW took a basic AC system, complicated it by spreading it out over a football field--and then stuck the AC back away 10 ft. from the inhabitants of the vehicle.

Sadly--not real efficiant for a rolling toaster oven.
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Last edited by Terry Kay on Mon Aug 13, 2012 9:15 pm; edited 2 times in total
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dhaavers
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PostPosted: Mon Aug 13, 2012 9:12 pm    Post subject: Reply with quote

^^^ Agreed.
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Terry Kay
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PostPosted: Mon Aug 13, 2012 9:21 pm    Post subject: Reply with quote

I would think the newbs to AC technology & operation would benifit by being book worms first---then start asking questions of how, why, & how come after they have the basics all nailed down.
Get the theory all dialed in first.
Understand what does what.
This would be the fastest way to to the moon I would assume.
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Last edited by Terry Kay on Mon Aug 13, 2012 10:05 pm; edited 1 time in total
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mbwesty
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PostPosted: Mon Aug 13, 2012 9:38 pm    Post subject: Reply with quote

Terry Kay wrote:


<<The high pressure port is behind the closet shelves.>>

Thanks Terry! Found them...

<<The dryer for sure, maybe the compressor.
I would at least service the compressor>>

The compressor the only servicible parts are the clutch and bearing?

<<2) Also, since I have the original service port so I probably should perform a 134 conversion on the system to take Red Tek?>>
No--leave it as it is.

I thought it is necessary to replace all the original R12 orings and etc for 134/Red Tek? I was going to buy the kit online...

<<3) Should I vacuum or pressure test the entire system for leaks first? And do I do that via the low pressure port?>>

Absolutley Yes---
It requires suction from both ports at the same time.

So I read somewhere to pull a 29" of mercury or something like that overnight? Is that a good number? Is the system isolated somewhere (compressor, condensor, evaporator) between the low and the high side?


I think your going to need one of these prior to continuing--
Good reading,,and will answer any & all of your questions on AC theory & operation

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Thx for the reference, I'll check it out...and thx for your input!

Tim
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Terry Kay
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PostPosted: Mon Aug 13, 2012 10:03 pm    Post subject: Reply with quote

<<The compressor the only servicible parts are the clutch and bearing?>>
The schraeder valve on the low side port, & dump & change the who knows how old oil in the compressor's crankcase.

<<I thought it is necessary to replace all the original R12 orings and etc for 134/Red Tek? I was going to buy the kit online...>>

For 134-A yes, no question.
Red-Tek no, unless you feel a burning desire to do that o-ring change--go ahead.
The only problem I can imagine happening is snapping fittings getting this job all done--especially up front on the condensor or on the wheel well mounted dryer.


<<3) Should I vacuum or pressure test the entire system for leaks first?>>

Sure, or after you swap to all new o-rings.

<<And do I do that via the low pressure port?>>

Both at the same time.
High & low ports in sterio.
It requires suction from both ports at the same time.

<<So I read somewhere to pull a 29" of mercury or something like that overnight?>>

Pull it down for a hour or two--the let it sit--gauges still on the ports--overnight is a good indication if you are going to have any leaks later.

<<Is that a good number?>>
29--30

<<Is the system isolated somewhere (compressor, condensor, evaporator) between the low and the high side?>>

The system changes pressures at the expansion valve--not at the other places you mentioned.
( well close to the evaporator)--but it doesn't do anything to the operating pressure.
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PostPosted: Thu Aug 16, 2012 3:32 pm    Post subject: Reply with quote

Spent about $170 got the manifold and a low-end vacuum at HF. So the A/C system has no pressure and it can hold a vacuum no more than 20 in of hg and it is leaking somewhere. So is there an easier way to detect where is the leak other than filling the system up with 134? I guess doing a visual on the entire system is a must and can one pressurize the system and do a soap bubble leak check?

Is there a part that is prone to leak first in this old system? The compressor clutch doesn't engage but I can turn the compressor but not very easily and I can feel the grinding dirts.

Thank you for your help! Tim
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PostPosted: Thu Aug 16, 2012 4:50 pm    Post subject: Reply with quote

Sounds like you have a BIG leak - check all connections & get all new o-rings.
Add a can of leak detector (refrigerant with dye) & have a look around again.

The old R-12 hoses can also leak right through the walls due to the smaller molecular size of 134a .
RedTek is less likely to leak through (more like the original R-12) but old hoses are old hoses.

Good luck - I started my AC project a year ago; no progress
this year...maybe more $$$ to throw at it next spring...???

It's all part of the fun!
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Terry Kay
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PostPosted: Thu Aug 16, 2012 10:56 pm    Post subject: Reply with quote

I'd start doing all of the o-rings I could get to first---

Might be the expansion valve is loose--seen this happen plenty.

Once you've got this all done , suck it down again.
See if it holds.

You take a look at all of the connections under the Van?
Rusted up?
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PostPosted: Fri Aug 17, 2012 9:10 pm    Post subject: Reply with quote

dhaavers wrote:
Sounds like you have a BIG leak - check all connections & get all new o-rings.
Add a can of leak detector (refrigerant with dye) & have a look around again.

The old R-12 hoses can also leak right through the walls due to the smaller molecular size of 134a .
RedTek is less likely to leak through (more like the original R-12) but old hoses are old hoses.

Good luck - I started my AC project a year ago; no progress
this year...maybe more $$$ to throw at it next spring...???

It's all part of the fun!


A big leak I think it is. So 134a probably makes good leak checking gas for its molecular size. We use to use He for that reason with a mass spec. Don't I wish I have that setup. So with that kinda leaks you think pressurizing the system a little to do a bubble leak check should be okay? I read a lot about vacuuming but have never read about pressurizing it and I just don't want to go do it without bouncing it off experts in this forum (like I didn't know the single bearing water pump can be ruined by overtightening the alternator belt).

Thx in advance!
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PostPosted: Fri Aug 17, 2012 9:16 pm    Post subject: Reply with quote

Terry Kay wrote:
I'd start doing all of the o-rings I could get to first---

Might be the expansion valve is loose--seen this happen plenty.

Once you've got this all done , suck it down again.
See if it holds.

You take a look at all of the connections under the Van?
Rusted up?


Should be doing an visual inspection soon. I am thinking about isolating the system from front to back (i.e. probably plug up one end from the drier connector and pull a vacuum from the compressor end) and hope to id where the leak is coming from. Thx for your help! Tim
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PostPosted: Tue Aug 21, 2012 10:05 pm    Post subject: Reply with quote

Terry Kay wrote:

You take a look at all of the connections under the Van?
Rusted up?


Hello Terry: I inspected the AC system and nothing seems rusted up. Lucky, a CA van.

So I started taking things apart in hope of finding the leak(s). I yanked the compressor and I am royally confused. I checked out the Sanden service manual online and I was expecting to see light brown color oil; however, I have tranny fluid looking oil coming out of the high/low pressure ports as well as from the drain plug. My guess is may be about 1/4 - 1/2 cup of oil came out of the drain and may be the same amount from the ports. I have a few questions:

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1) Is that PAG or ester oil? Do they have color?
2) Is the compressor bad as it seems that the oil (same oil) may be leaking into the cylinders?
3) What kinda oil should I put in the compressor case, and how about for the line?
4) Is it possible to clean out the compressor to put new oil in without mixing?

The pulley runs smooth and I can turn the compressor with a socket wrench without any obstructions. Tomorrow I am going to take some resistance measurement to checkout the clutch and I am wonder if I can just apply 12V to the clutch to see if it engages. A good/bad idea?

Thanks for your help!

Tim
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Terry Kay
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PostPosted: Fri Aug 24, 2012 5:15 pm    Post subject: Reply with quote

The color of the oil doesn't indicate much, except it sure isn't mineral oil.

I've seen synthetic oils dyed green , blue--never red.

Who knows what's in there??
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PostPosted: Fri Aug 24, 2012 6:25 pm    Post subject: Reply with quote

Could the red be the remains of some leak detector additive? Just a SWAG.
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PostPosted: Fri Aug 24, 2012 9:51 pm    Post subject: Reply with quote

I highly doubt any leak detector got into the crankcase of the compressor.
it'd be in the lines & operating component's only--

Besides--the leak detector stuff is yellow / green , not ATF red.
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PostPosted: Sat Aug 25, 2012 7:42 am    Post subject: Reply with quote

Great video Aleric, I'm sold. My '89 has one hi/low pressure switch in the left "D" pillar. One switch. ($180 for a new one.) The Bentley shows separate hi and lo switches. After filling the system w/ refrigerant (134a) the clutch would still not engage the compressor. Being cheap as I am, I gave the switch a rap with the handle of a screwdriver and wala! clutch engaged! I now have to do this once a season ( via a small hole in the cover plastic with a small drift pin to do the rapping)
Replacing all the hoses as the 134a migrates through the freon hose.
A side note: 134a gives me 49 degrees f at the overhead fans.
CVBILL
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PostPosted: Sat Aug 25, 2012 5:17 pm    Post subject: Reply with quote

Terry Kay wrote:
I highly doubt any leak detector got into the crankcase of the compressor.
it'd be in the lines & operating component's only--

Besides--the leak detector stuff is yellow / green , not ATF red.


I agree. I took the oil to several A/C shop they are puzzling, too. The mostlikely scenario as suggested was overheating but that oil color is really red.

Terry, I thought I read from some posts that some oil do leak from the crankcase to the head. Am I wrong on this?

So, I isolated the leak to be in the condensor. I removed the compressor and plugged the lines. Then I removed the drier and checked the vacuum at both ports where the drier used to be connected. The backend evaporator held a tight vacuum at 30" Hg, but the frontend condensor was only able to pull a 20" Hg at most. I further tested both of the long high pressure hoses and they held a tight vacuum, too. I'll yank the condensor the next few days since it was only able to held a 20" of Hg vacuum.

For the compressor, I turned it with a drill and it ran without interruption and I could feel the pressure at the head. The only thing was the Sanden spec said the resistance in the field coil should be no more than 4.4 ohm and mine was 4.7 ohm. So anyone has experience with this ohm number and am I going to have problem with the clutch engaging? Should I just go ahead and put in a new clutch?

Also, I thik I am going to do a rinse inside of the compressor with the destinated oil (ester or PAG) does anyone has a better suggestion on how I could clean out this red unidentified oil inside the compressor? I am planning on reusing it.

Please let me know and thx for your help! Tim
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