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Old July 6th, 2017, 15:18   #1
AndyBees
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Default AC Expanison Valve screen

To the "old school" crowd or late comers familiar with R-12 Systems... (Now an R-134a system)

I made the stupid decision two years ago to put "stop leak" in my 84 Vanagon AC system (ALH Engine with Jetta OE Compressor). Well, it keeps plugging the screen in the Expansion Valve. I've cleaned it once (last summer) and it is now plugged again. I did some connector repairs at the AC Compressor, new dryer, etc. Right off, the compressor pulled a vacuum on the Low Side and high pressure on the High Side with less than a can of R134a.

So, I removed the Expansion valve to find the screen plugged again.

Question, would it hurt to leave screen out?

We were hoping to hit the road Saturday morning on a 30 day journey ... this issue (and a couple of others) has set me back at least two days..
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'84 Vanagon '02 ALH TDI engine(32 to 35+ MPGs consistently) Malone Stage 1 tune. Road trip to Nova Scotia 2013. Road trip to Alaska summer 2014 & 2016, 11k & 12k miles. 71k miles on install, Jetta Cluster odometer currently at 200kk miles.

Last edited by AndyBees; July 6th, 2017 at 15:38. Reason: Clarification
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Old July 6th, 2017, 18:20   #2
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Well, I got an answer via a PM response.

Seems there is not a function issue with respect to the Expansion Valve doing its job (compressed liquid to a gas) if the screen is left out. However, without the screen, junk will end up in the evaporator. I'm not sure that would hurt anyway since the junk come from the compressor, hoses, condenser, etc.... guess it would just keep circulating.

So, I'm leaving the screen out........... a plugged expansion valve is a dead expansion valve, is how I see it! Maybe by next summer, I can replace all those 33 year old hoses and flush the system!

See you on the road....
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'84 Vanagon '02 ALH TDI engine(32 to 35+ MPGs consistently) Malone Stage 1 tune. Road trip to Nova Scotia 2013. Road trip to Alaska summer 2014 & 2016, 11k & 12k miles. 71k miles on install, Jetta Cluster odometer currently at 200kk miles.
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Old July 7th, 2017, 10:36   #3
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Have you tried to flush the system? May or may not help, since you can't really flush a compressor, but should get most of the rest. Also, no all stop lrak products are solids/particulates - IE some can actually work, but you need to choose carefully, and as noted, none are as good as an actual repair.

(Sorry, just reread that you did not flush . . . nothing preventing that even with the old hoses, though . . . just more work, but if the syste is open, you are most of the way there anyhow.)

Last edited by tadawson; July 7th, 2017 at 20:30.
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Old July 7th, 2017, 10:58   #4
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Ya, I'd say it's time to completely flush the system. I'd rather replace a screen at the TX valve than have to try and un-gunk the evaporator. The evaporator is probably parallel flow, so it might not be able to be flushed!

-J
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Originally Posted by BRUSSELS BELGIAN View Post
Maybe I should pay MYSELF to do bad work on my car!
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Old July 7th, 2017, 14:26   #5
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Well, the system has been somewhat flushed going back to 2012 when I first converted it to R-134a. As I stated, its pushed by the Jetta compressor with the Refrigerant Control Valve (RCV) removed and replaced with a big bolt and nut. With the RCV removed, the compressor operates is very similar to the OE for the Vanagon.

Below is a pic of the RCV ....



Below is a shot of the bolt replacing the RCV...



And, below going back together you can see the bolt and nut in place of the RCV.



This set-up worked fine in the summer of 2012, 13, & 14. Then, a leak developed at one of the "adapters" (welded mod to mate the two systems) resulting in a loss of refrigerant. So, being lazy, I vacuumed the system, charged it and added some stop leak. Before that summer (2015) was over, the screen was plugged in the TXV (Thermal Expansion Valve). I removed it for cleaning ........ plugged really bad with a glue-like substance which I assume was the Stop Leak junk.

Fast forward to late spring 2016, I removed and cleaned the screen before heading out on a 30 day road trip............. worked fine until about the last 4 or 5 days. Until about two weeks ago, the Van hasn't been driven over 1500 miles since last August.

So, again two weeks ago, I find the TXV screen plugged (high side pressure too high and low side almost at a vacuum). I removed the TXV and cleaned it. I also disassembled the AC Compressor for inspection (have an extra if needed). It basically looked the same inside as it did 5 years ago. I did drain and add 3 oz of PAG 100 oil. I also added about 2 oz of oil to the system. (I had it off to replace the pulley bearing....... so, was already there is why I did the inspection.)

Below is a photo of the AC Compressor 5 years ago.... (FWIW, I reused those gaskets without any leaks ... stay nice and clean.



Checking all the fittings, etc., 5 years ago and again this week as well as having a section of hose cut out and spliced (due a hole caused by rubbing on the chassis), the hose looked really nice inside. (I did flush the evaporator 5 years ago.).

Anyway, I vacuumed it down to about 29 inches and it held overnight. I charged it today with slightly over 2 cans of R-134a... seems to be working okay.

I do agree! Those 33 year old Uniroyal hoses are past due to be changed out.
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'84 Vanagon '02 ALH TDI engine(32 to 35+ MPGs consistently) Malone Stage 1 tune. Road trip to Nova Scotia 2013. Road trip to Alaska summer 2014 & 2016, 11k & 12k miles. 71k miles on install, Jetta Cluster odometer currently at 200kk miles.

Last edited by AndyBees; July 7th, 2017 at 14:29.
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Old July 7th, 2017, 17:50   #6
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I always wondered why you removed the control valve. It should work great with it - the clutch simply won't need to cycle.

-J
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Old July 7th, 2017, 18:31   #7
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Well, Compu_85, someone back in 2012 put me on a link with a story about removing the RCV due to it not working with the old style TXV. That is the only reason I done it. A year or two later, someone told me that the system would work just fine with it.

The down side is, the smaller electric clutch on the TDI compressor cannot handle kicking in if the pressure has not pretty much equalized. So, I just turn the temp setting to max until the vehicle cools down then back it off until the compressor kicks-out (light in dash comes on when the compressor kicks-in)

So, maybe I should have re-installed the RCV last week when I had the compressor apart for inspection.

..............
Okay, I took it for more than a 20 mile ride this evening.

Outside ambient temp > 75.6f (the ambient today was 86f when I charged the system)
Temp coming out of vent > 41.6f

Once the Van cooled off, I turned the temp control down until the compressor kicked-out and then turned it down a bit more. When the temp of the air went up to a little above 52f the compressor kicked-in. Then when the temp got down just above 44f the compressor kicked-out. I observed this cycling for about 14 miles or more.

So, I think it is fixed for now......

Side note: If I had not got the flu back in late February, which put me down for almost two months, I'd addressed the AC much sooner! (tough getting old)..
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Last edited by AndyBees; July 7th, 2017 at 18:33.
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Old July 13th, 2017, 11:06   #8
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One of the leadmen I work with spent over 20 years at Reefer Services, (refridgerent, not medical marijuana). I remember him telling me to use oil and hoses specific to the refridgerant used, can cuase hose deterioration. The expansion valve had some "flashing" purpose.
He is quite sharp, having done service calls on reefer trucks for most of that time. If you want me to throw a question at him let me know. You may have to PM me for me to notice.
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Old July 17th, 2017, 08:18   #9
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Well, the AC system worked great ........... until the high pressure hose ruptured.

We were on our way to Alaska and just south of Indianapolis the hose gave up. So, we did a 180 and returned home. I'm now working on a 10 day window that will close Saturday. However, if I get it repaired and going, we will extend the departure to Monday, July 24th.

Right now, via internet, I am working with coldhose.com. Using my measurements, photos, etc., they are making up a set of new hoses, both pressure and suction sides with new fittings, ports and adaptors to the Sanden SD7V16 Compressor on the TDI engine.

Mean while, I've removed everything for flushing.....
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Old July 17th, 2017, 11:46   #10
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Pm'd you, will get back when I have some info. I think I remember Bill telling me the R12 hoses would eventually give out. I have r12 in my k5 and had considered changing to r34
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Old July 17th, 2017, 12:57   #11
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About the only issue I know of with R12 hose vs R134 is that the older hose is not barrier hose (dual layer) and the R134 molecules will slowly be lost through it. A far bigger issue in changing refrigerants is oil compatibility, since some mismatch so poorly they become very acidic . . .
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Old July 17th, 2017, 13:36   #12
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Quote:
Originally Posted by tadawson View Post
About the only issue I know of with R12 hose vs R134 is that the older hose is not barrier hose (dual layer) and the R134 molecules will slowly be lost through it. A far bigger issue in changing refrigerants is oil compatibility, since some mismatch so poorly they become very acidic . . .
Exactly, first a little info on r12 to r34 swap. An 80% charge rather than full charge unless you changed hoses. Removing ALL mineral based oil from the system. They used r11 that changed to liquid at atmospheric pressure.

But, in the end, the ester based oil from r34 will break down the r12 hoses.

So, I assume you are getting hoses that are r34 compatible?

Bill said brakleen can be used to clean the compressor, but most likely air pressure may be your only alternative to cleaning the rest.

The orifice serves two purposes, catching contaminents and flashing the refridgerant to aid in converting it from gas to liquid on it's way from the condenser to the evaporator

Hope this helps
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Old July 17th, 2017, 15:57   #13
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As a side note here, if anyone should per chance locate some r11, DO NOT OPEN IT IN AN ENCLOSED ROOM. It turns from gas to liquid at atmospheric pressure.
So when you open it, the oxygen in the surrounding air will be absorbed. It could drop you quite fast.
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Old July 18th, 2017, 13:40   #14
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Well, I've ordered both long hoses for the Vanagon that will mate to the "adpators" for the Sanden SD7V16 Compressor that's on my TDI engine. Coldhose.com has a good on-line "custom build" work page as well as lots of other good info and all the parts you'll ever need.

Okay, maybe I'm going about this the wrong way, but I'm doing a triple flush. First, I'm using Mineral Spirits to breakup the oil and any chunks of debris that may be clinging to the inside of the evaporator, condenser, etc. Then, I'm following with two blow-throws of Acetone! Acetone will flush-out the Mineral Spirits and any left-over residue of AC oil(s). Acetone is good about absorbing moisture and evaporates really fast.

I just finished flushing the Evaporator. I captured the blow-out stuff ......... (no debris) nothing but a reddish color liquid (AC oil, Mineral Spirits and Acetone). The last blow-though was clear Acetone!

I'm going to tackle the Condenser without removing it from the vehicle. It appears the loops all weave down to the bottom. Thus, it should blow-out nice.

Then, I'll do the two short high pressure hoses (from bottom of Condenser to Dryer and Dryer to Expansion Valve/Evaporator).

The new hoses should not need a flush (they are R-134a compatible).

I'll flush the Compressor again as well.

Side note: Has anyone read about "adjusting" the expansion valve? It is adjustable!
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'84 Vanagon '02 ALH TDI engine(32 to 35+ MPGs consistently) Malone Stage 1 tune. Road trip to Nova Scotia 2013. Road trip to Alaska summer 2014 & 2016, 11k & 12k miles. 71k miles on install, Jetta Cluster odometer currently at 200kk miles.

Last edited by AndyBees; July 18th, 2017 at 13:42.
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Old July 18th, 2017, 15:31   #15
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Does "adjustable" mean it adjusts itself as it captures debris?
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