R-134a system HELP!

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R-134a system HELP!

Postby Cobra » Thu Oct 20, 2016 1:52 am

Hello
My name is Matt and I joined this forum because I need help with an R-134a system on my 1995 dual A/C van.
Without going into detail, I'll just say I needed to replace my compressor and rear evaporator due to Super Storm Sandy.
I had the new compressor on the vehicle (never ran) for several years before water entered open lines serving the rear A/C unit and seized the rear fan. I plugged off the rear unit, installed a new orifice, accumulator and compressor with new oil. When I tried to start the compressor it was seized. After much coaxing it broke free ran quiet and cooled nicely until I tried going on the parkway. Once I sped up the compressor it shut off on high pressure switch.
I purchased a new compressor, rear evaporator, rear expansion valve, accumulator, condenser, and high pressure switch and orifice. I blew all the lines out with a compressed air using alcohol and compressed air. I added 2.5 ounces of oil to the compressor, and 4 ounces to the accumulator to make up for the new components. I evacuated the system made sure it held a vacuum and recharged. It's doing the same thing! When started it seems to be under a heavy strain squealing the belt until it runs for about 2 minutes them begins cooling at about 38 psi suction 175 psi head. The air is not as cold as it should be, suction line is sweating. If you accelerate the engine the belt begins straining again for a while then quiets down, at least this time it is not going off on high head pressure. Also I forgot to mention I changed the belt tensionor, idler pulley and belt (continental cross ribbed).I slit up the oil between the inlet of the evapoator and the accumulator, I was afaid too much oil may slug back to the compressor.I also added the exact Delco oil perscribed for this compressor with 134a
I would appreciate any advice.
Thanks Matt
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Re: R-134a system HELP!

Postby Tom Greenleaf » Thu Oct 20, 2016 11:17 am

Welcome Matt:

Charts can be wrong and I can be wrong but I have a horrible feeling all this was in vain and would need redoing all over again for lack of oil lubrication listed at 11oz of PAG 150 with 68oz 134a. I see you have 6.5 oz oil - oops. Not enough if a single system.

Alcohol to flush? IDK - use flush for A/C some will use lacquer thinner and copious compressed air.

Compressors are usually up high with m.y. 1995 area so slugging isn't as likely as a low mounted compressor.

Take pressure with front on only or they will be erratic IMO and observations on similar, Suburbans to be exact.

Temp pressure relationship is only valid with all observations including just ambient and output temps plus at what RPM and fan speed or aren't helpful yet.

Also if this wasn't mostly charged before first start up or compressor spun prior to installation it was probably harmed or destroyed mostly rather quickly and the debris is all back where it would be all over again.

Pressures you listed would condense refrigerant well or much, performance if any lousy and the dragging on the belt is probably the compressor seizing again and hate to say not a surprise.

Bummer. At this point and age of the van do you want to spend all this money and more all over again? Of course up to you.

This is good into also listed up top in knowledge base but the link to it is here. Long read as it's critical ever step of the way or this common total failure is the tuition for doing it incorrectly unfortunately,

Tom

>> Good read link >> http://aircondition.com/tech/questions/ ... Procedures
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Re: R-134a system HELP!

Postby Cobra » Thu Oct 20, 2016 1:23 pm

Thanks Tom

I followed the instructions that came with the new Delco compressor (not rebuild). It stated the compressor is shipped dry, and to add 2 ounces of oil if no oil is measured from the old compressor. The slugging I was concerned about was oil slugging not refrigerant. I was hoping on start-up the oil I put in the accumulator would be added to the compressor. I'm going to research Delco and see what the actual oil capacity should be, close to 11 ounces? I have repaired and recharged auto and stationary systems over my 40 year career. I am a Chief Operating Engineer HVAC for Disney over 37 years, this is not my first rodeo. My experience has been that most times things are never micro critical, usually, a more major malfunction causes problems. 2 ounces vs 11 ounces is major. Looks like I may have repeated this error twice.The first time I blamed leaving the old compressor uncharged on the vehicle for about 5 years caused internal corrosion. I appreciate your detailed reply. I will read you attachment. The van has only 55,000 garaged miles, its like new. It got flooded by sandy up to about 4" above the doors. It still runs great and I us it for towing a trailer. At this point, it's man against machine, I don't mind investing in more time and parts, its still only a fraction of what it cost to have it done, and I have seen what has been done by some shops, I'd rather break it myself. The original compressor failed shortly after I bought the van new. It was replaced under warranty. Second time the orifice and TXV screen filled with metal debris from the failed compressor. I am tempted to run it for a while hoping it could be only the belt slipping. This vehicle always had a noisy belt. When the belt stops screeching, the compressor runs quiet.
Thanks again
Matt
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Favorite Refrigerant: R134a

Re: R-134a system HELP!

Postby Tom Greenleaf » Thu Oct 20, 2016 8:09 pm

OK - it's not a stationary set up so oil matters AND it just sits still until the charge is adequate to cool while charging. If you can envision it's just setting there at the bottom of parts till it can make the full loop and constantly lube a compressor or is about like an engine with no oil. Game over.

I don't redo compressors. The sealing surfaces can be just a Teflon coating that hold pressure. 1 whole minute running dry it can be destroyed. It would only be that but it threw junk/debris now you said more than once caught up in condenser and "O" tubes. It doesn't clean out of those and even replacing them if about the pepper you might put on a meal's worth is already clogging it up again.

The compressor and parts makers are NOT responsible for total details of proper installations. Worse, they don't say you may have had a minor problem to replace a compressor other than XYZ and it trashed everything else! Yikes - no second chances.

OK - some you can find specs and capacities on OE stickers on OE parts. After than the sticker doesn't know what vehicle the part is going in so not included.

NAPA, Autozone and other resources can tell of capacities. When two agree it's credible. You can buy software for just your vehicle - I don't as it's a fee to do this stuff for free wishing you the best luck plus retired from it so not paying for what I can't find for spec.

IMO - don't just jump low pressure switches and charge that way on vehicles. If you have a full well held vacuum and warmer source of refrigerant it will put enough into the system to get going on it's own - this one would cycle.

Note on slugging or compressing a liquid either oil or liquid refrigerant can be the case. Liquids don't compress so a valid worry. IDK - either belt would just slip and stop what you are doing or in this case caused damage - could have been either way but new belt and tensioner it had a good grab..

Pumps for many things can' t be run dry, for water, power steering or other uses totally. Some can - these can't.

Problem is a lot to do with more efficient parts with smaller passages that will not flush out or not flush out well enough.

The end all it automotive A/C is not tolerant of a mistake. Worse the systems in place to shut it down to save itself are rarely on time to really save the show.

Compressor's will be warrantied. The rest would not be which is more costly than this compressor all added up.

Your call. You can go for it again or get help with the critical areas where continuous self destruction is a risk and is,

Tom
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Re: R-134a system HELP!

Postby Cobra » Thu Oct 20, 2016 10:52 pm

Tom
Thanks again for the info. I'm frustrated being stuck at work thinking about this. If I go for a new compressor I'm going for everything else again. My big misunderstanding was the amount added to the compressor itself. I assumed the oil was distributed throughout the system, then circulated once started. If you don't mind another question. In you best guess, would the refrigerant be carried immediately by the refrigerant, or would most of it be trapped in the accumulator for a while? I charged liquid on the high side when I broke the vacuum before starting the A/C. I just want to give it every chance before dismantling it.
I looked at the oil bottle, (boy that synthetic oil is really good stuff). I used about 8 ounces total out of 16oz, as I said distributed in the evap. and accumulator, some spilled when I was installing the accumulator. I came home to day and could not resist starting it.
The belt chirped a little while charging the battery then I engaged the clutch. it ran smooth, cooled and did not squeal. I did not leave it on that long, and did not race the engine. This is why I am trying to ascertain if I put a hurting on it or damaged it severely.
I'll keep you posted

Thanks for you reply it has not gone unappreciated
Matt

P.S. I think I answered my question while typing. The oil would have to be in a mist or vapor form when leaving the accumulator which means it would take a while to precipitate back in the compressor.
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Favorite Refrigerant: R134a

Re: R-134a system HELP!

Postby Tom Greenleaf » Fri Oct 21, 2016 5:58 am

First - sorry this isn't live response - just when someone has time and consider as opinions and best guesses. Can't compete with being there.

Yes - it is a lot to take in that you can do your honest best job and mess it up so easily. Question is not what to do and verify it so you don't do this again if what I think. Been out of this a looong time now so pretty much just my own and the few I come across now. For my own now seriously low mile, low use vehicles plus heading into Winter I do always listen carefully to compressors for noise. Can't tell it they are making cool as it's already cold here, heating only season for me. When the first nano second of warm enough ambient air comes I purposely listen to compressors working. There's a death rattle when they are low very slight or enough to unplug a compressor and deal with it later - my own or late friends and family. Then find and fix but at least warn not to use A/C at all if not blowing cold up to leaving a thermometer in the vent to know and do that all the time. Newest vehicle will be 20 years old next month - other used goes away for Winters unless remarkably clean driving as salted roads is the problem with long vehicle life where I am. First check is A/C, still an all OE R-12 car pushing 30 years old and count on it!

Check "O" tube now. Bet it's full again which is pretty lousy news.

On question where does oil settle? Guess is when off for a while most is at low areas of condenser, some in evaporator, some in accumulator and any low spots like a fog of oil has what it does is the damp fog thru the system when it is moving. Boy, wish there was a glass system to put what goes on, on a video you'd really see what it's doing oil and when refrigerant is liquid or gaseous state. There are some nice generic diagrams of system operations but what I find leaves out the oil factor.

That's my own personal habit to avoid needing compressors which grows to needing so much more since forever and has worked quite well for me and many others.

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For you: See as best you can where you are right now. Do you wish for new stuff (compressor will be on warranty) or try to save condenser. Keep in mind hoses and anywhere refrigerant has gone needs clearing out and want to know it. Catch oil and anything checking for junk. Measure oil that comes out of items to be discarded when partial work is to be done so you know what was in there like drill a hole in accumulator and warm it up - measure what comes out. It's almost always OK to knowingly be a couple ounces OVER with oil but know it as the only time you know how much you have in there is from totally flushed out and empty what you put in.

You were right to put oil up stream to get to compressor early. Early in this case is seconds not minutes! That is kind of true when a vehicle has been sitting for months as well! I dare say that is why this has had any work done at all since new with just 50K on it and as old as it is plus you didn't say the lines all busted off, threads welded together so something went right.

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Wish others would chime in too, some from the southwest of US and Mexico here can speak of problems I'll never see or have seen locally and probably vs versa.

Check other sites - YouTube things and all you can muster. Take the web and info for what it frequently is too. It's not always true or plain false which is dangerously worse. Knowing the difference is all on YOU.

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Other: Site is slow and does get spammed hard. Sometimes it just doesn't work well also? The PM (private message system is here and it too only works marginally for me - don't know why.)

Personal. You can find me if I'm not dead or a computer problem yet and that stuff happens out there! Am only at all free to you sites all volunteers so no motivation to steer you wrong and no joy in being wrong or miss an important detail.

However you approach this now consider it all a new issue all over again and take your time. As you will hear and have found out tiny mistakes are costly in this and a lot of things vehicles or otherwise.

Best of luck and I will keep up as long as site works an or if you find me,

Tom

Other user names to seek good at your vehicle: ACProf, GM Tech, Nacho listed above. Not sure who can or will respond?
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