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jjrbus
User
Jul 27, 2015, 3:43 PM
Post #1 of 65
(4816 views)
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Greetings from cooking hot and humid SW Florida. Been getting lot's of help here but got side tracked and need to post an update.
93 Toyota motorhome V6 Auto R12 to 143A conversion. Replaced almost everything except hard lines and pressure switch. System would not hold vacuum over night and was told here a pressure test was in order. Managed to get ahold of nitrogen bottle and gauges for test, cost me 1 case of beer, maybe I should give 2?
Very little info online for testing autos with nitrogen, kind of a grey area. Any way working in between rain and lightning so taking long time. Using soap and water cannot find leak, so must be in evaporator, of course hardest thing to get to. Take it out hook it up to system without case, pressurize and ONE thing I did not replace is blowing bubbles, tiny bubbles in the wine, make me unhappy, I don't feel fine. Don Ho 19??
So off to buy switch, so far so good. Many thanks guys. Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 27, 2015, 4:20 PM
Post #2 of 65
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? What did you do a vacuum with and see it not hold before just getting gauges? Gauges can leak too and retrofit adaptor fail.
Nitrogen testing is done with a tad of R-22 and a sniffer for leaks.
Leak finding is using all methods available and some are quite elusive. Oil evidence or dye might be in system already, bubble test is OK for some but limited.
This isn't very DIY friendly and harder yet as a retrofit with the age also.
Again - holding a vacuum is step one. If it can't it may not be the system but the way it's hooked up or tools used. If it did hold a vacuum that's not proof that it would take a charge and work at all just the first step before you would move on to more.
Do you have a clue how to charge this up if it did hold? How much refrigerant to put in and measure it?
If not send this out. You'll run into more snags than I can count getting it right if it was ready for charging,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 27, 2015, 5:11 PM
Post #3 of 65
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Hey Tom, I think he found the evaporator was leaking when he soaped it. Hopefully it holds vacuum after he gets that replaced.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jul 27, 2015, 5:12 PM)
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Tom Greenleaf
Ultimate Carjunky
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Jul 27, 2015, 9:40 PM
Post #4 of 65
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Thanks - Trying to recall the orig thread on this. Evap by default as everything else is fine.
Jim - IDK what a sniffer costs now but they are worth it - no test is really perfect for leaks until you can put your finger in hole while it leaks.
May have said, evaporator leaks if you find oil in vent tubes are about as conclusive as you get if nothing else but probably would require that it worked properly sometime recently?
T
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jjrbus
User
Jul 28, 2015, 5:19 AM
Post #5 of 65
(4784 views)
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Thanks for the responses. I should have more clear it is definitely old low pressure switch leaking, bubbles coming out electrical end of it. And of course nothing is easy! Original low pressure switch is marked Denso 8505 and is not available that I can find.
After many web searches the only switch that shows is 4 Seasons/Murray 35829 The electrical connector looks different than what I have.
DescriptionSystem Mounted Binary Pressure SwitchOff29/391On30/304PSI ActivationLow opens at approx. 28 PSI +/- 10. Closes at approx. 29 PSI +/- 10. High openHarness Connector[37219]
Other than it is the only one I can find, how do I know it is the right switch?? Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 28, 2015, 5:44 AM
Post #6 of 65
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I just looked up one year for the switch, in stock $18.99 now - no problem. You must have your pressures wrong as this cuts out at either 28PSI or 451PSI is what it said acting as a dual, binary switch. Some used to use a little screw to adjust and usally (my luck) leaked as you said if touched later.
Certainly not worth too much fuss over the costs on that. The deal is it's now (model year 1994 up) only dealing with 134a specific pressures.
FYI - Assorted vehicles were all R-12 set ups factory converted for a model year or two for parts and specs. '93 was the year the NATO cooperating countries quit making new R-12 and certain vehicles could be sold with either when new.
Any which way it has to work, not leak and fit,
T
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jjrbus
User
Jul 28, 2015, 6:35 AM
Post #7 of 65
(4777 views)
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Thanks for the quick response! If you have no issue with the switch I am going to go buy one. Jim
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Tom Greenleaf
Ultimate Carjunky
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Jul 28, 2015, 6:51 AM
Post #8 of 65
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Your pressures said YOUR switch cut off and back on in ONE PSI? Doesn't make sense to me.
Just looked again - hope specs show for '93. This listed same part # as '94 and used different refrigerants when new.
*****************************************Product DetailsPart Number:MT0354Weight:0.062 lbsWarranty:1 YRNotes: A/C binary switch
Hi-low pressure cut-off.
Activation Pressure (psi):28Air Conditioning Switch Function:High / Low Pressure CutoffColor / Finish:BlackConnector / Terminal Configuration:SpadeDeactivation Pressure (psi):451Package Contents:
Binary Switch - High Pressure Cut-Off / Low Pressure Cut-Off
______________
^^^^Hope that showed, was there.
T
PS on edit: Switch is to purposely shut down system at those extremes. Personally I would shut down lower than 451 listed as that's too close to bursting points IMO. FYI again, you don't want system to engage compressor when pressure low for assorted reasons. Too low is either too low on charge or too cold for it. No or low charge oil quits moving and compressor would be toast in no time.........
(This post was edited by Tom Greenleaf on Jul 28, 2015, 6:59 AM)
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jjrbus
User
Jul 28, 2015, 9:22 AM
Post #9 of 65
(4766 views)
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NObody had the four Seasons in stock, I stopped at NAPA and they had NAPA part #207092. Which also has the Four Seasons part # stamped on it of 35829.
I removed the Denso switch that is leaking and it shows off 27 and off 2.1
The NAPA switch shows off 27.0kg and off 2.0kg
In over my head. Jim
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 28, 2015, 9:36 AM
Post #10 of 65
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You are probably worrying too much about the pressures when it does what. Said, it needs to know to shut off power to compressor in extremes hoping to prevent damage in a failure.
If you just had a wire color matched, plug that matched one it would probably be correct or close enough. These pressures are in line with most systems.
Understand if the compressor was just building all the pressure it could it would blow out the weakest link or about all had a blow out valve to do that.
Low pressures as said can mean more. If system was empty it shouldn't send power on to compressor nor if too low like even a cold day pressure could plummet (not so much where you are) and return liquid refrigerant back to compressor which is trouble as it's meant to compress gas in vapor form not liquid.
Right now is mostly can't be a leak. I think it's #s listed you have and I found could be incorrect on yours or a typo. Why would a pressure sensitive ON/OFF switch shut off and back on within one PSI as you posted?
FYI - you shouldn't have to get parts on line this cheap. It's in stock meant for this now in person. If NG take it right back. In person gives you the chance to match it up right when you get it,
T
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jjrbus
User
Jul 28, 2015, 11:48 AM
Post #11 of 65
(4759 views)
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The new switch is installed, I have they system pressurized, little early to tell yet but it seems to be holding. Will let it sit till tonight or tomorrow morning before doing anything.
As far as the wrong numbers, it was a copy and paste. So the website is wrong!
I do worry too much about things, but have no idea what I am doing and find some things confusing.
All this rain, I need to mow the lawn while I am waiting. Jim
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Tom Greenleaf
Ultimate Carjunky
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Jul 28, 2015, 2:01 PM
Post #12 of 65
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Gotta finish my own lawn too! Laugh.
Why are you pressure checking and with what now? I'd just see if it help a vacuum again.
Just know some trivia/facts: Vapor molecules are not the same size. Air pressure may or may not leak when refrigerant will. 134a is a particularly small molecule would leak where other gasses would not.
You can go up in pressure sky high but limited to atmospheric pressure for vacuum leak check and hold. We generally live in 14.6998 (something like that close) of air pressure at sea level so any leak that hold is only holding OUT that much pressure of ambient air. Also - some dang leak will hold vacuum but not pressure and vs verse.
Rubber alone leaks gasses thru it. 134a calls for "barrier" hose which this might have had new or not. "O" rings and all made for this and guess is nothing sold new that isn't the correct rubber type by now.
Plain hot today and back to the dang lawn now like YOU
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 28, 2015, 4:38 PM
Post #13 of 65
(4749 views)
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Don't forget to trim the hedges!
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Tom Greenleaf
Ultimate Carjunky
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Jul 29, 2015, 3:38 AM
Post #14 of 65
(4737 views)
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Don't give away my tricks DS. I actually use a running chain saw on a rope and swing it around for hedge trimming. All done with that for the year.
It's A/C time here for a little while. Real hot (95F), some humidity never like SW FLa. or about anywhere South of I-10. It's all yours.
Back to this truck. I'm not so worried about the high side cut out unless it so wrong compressor can't work. If not leaking it's probably ready to charge up and test out,
T
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jjrbus
User
Jul 29, 2015, 6:37 AM
Post #15 of 65
(4729 views)
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Got the lawn done yesterday, except trimming. I only trim every other cut. Grass grows incredibly quick here in summer.
AC system held nitrogen pressure for 10 hours. So looks like time to vacuum and charge. Not able to do it today, is wife's day off and she needs to be catered to.
Now have question?? I put new dryer in 3 weeks ago and system has not held pressure or vacuum since. I have had to open and close system to replace part but never left the system unsealed, put plugs in holes when left apart, always put back together as quick as possible. Should I replace the new dryer is the question??
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Tom Greenleaf
Ultimate Carjunky
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Jul 29, 2015, 6:59 AM
Post #16 of 65
(4726 views)
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Nitrogen! The molecule is large so alone it's great for not leaking and a harmless gas. Used specifically for it's properties in tires to hold their air pressure and doesn't react much to temp changes, air does. If you don't put a smaller gas molecule that can be sniffed out you wasted time IMO.
The snag is you need a CFC (hydrocarbon) to sniff out a leak and can only do that if you have the right conditions. I'm done except my own for a long time now. Would go find elusive leaks for shops only to find they just cleaned the engine with spray something and sniffer is useless so each method has it's limits and benefits.
Laws say NOT to purposely put refrigerant into a known loss of it situation. If by mistake what can anyone do? That makes it a rock and a hard place to both stay legal and find any elusive leaks.
Most systems with a suspect leak would have full static pressure of 134a with about 4oz charge but would use one with A/C, UV dye in it too.
Where are we with this? Ready to try to charge it or keep looking for leaks? Sorry for some sideline fun with hedge trimming in this but many of us read a lot of the same all the time and need a laugh now and then. Just let that go,
Tom
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jjrbus
User
Jul 29, 2015, 1:01 PM
Post #18 of 65
(4718 views)
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Thanks for the responses. I'm ready to charge! I stopped at WalMart to pick up a case of beer for neighbor I borrowed the nitrogen from. I found made in the USA 134a and bought 3 cans of it. Not till I get home did I realize it also says "Polar freeze additive" I need to get bifocals or start carrying reading glasses with me. I suspect I let the price of $6.88 a can sway my judgement!! The can does say tetrafluoroethane and proprietary ingrediants. I want 134a and not proprietary additives.
I should be able to get 134a and take a shot at this tomorrow, depending on the weather. I know I should hire this out, but I have spent a couple months putting this together and reading about it. So it would be a big let down to have someone else finish it.
Jim
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Tom Greenleaf
Ultimate Carjunky
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Jul 29, 2015, 2:35 PM
Post #19 of 65
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See that non pure 134a and can't know what else is in it. General idea - if anything was really better it would be specified by makers and none do so don't buy that. It does seem to sell well which is what a store cares about not if it works or not.
Pure products only for A/C still. It's out there just less bragging on containers or rather a lot of bullsh*t,
T
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jjrbus
User
Jul 31, 2015, 10:09 AM
Post #20 of 65
(4686 views)
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Took some running around but found 100% 134A, Dupont Suva at $9 can. Also bought a can tap for $5. When tapping can, handle disintegrated on cheep Chinese junk tap!
System took 134A up to about 75lbs. Turned off manifold and started truck, AC clutch will not engage! Spent the morning checking fuses and switches, everything appears OK. Clutch will engage with 12V applied to it and compressor still turns by hand. With truck running and AC on there is no voltage going to clutch. I considered jumping pressure switch, with 75 lbs in system it does not seem like I would need to?
I am stumped and in over my head so called Mike the mobile AC guy, who will be here later today or tomorrow morning. Hate to spend the money I put away to buy you guys dinner, whats a poor boy to do??
Jim
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Tom Greenleaf
Ultimate Carjunky
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Jul 31, 2015, 12:14 PM
Post #21 of 65
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? Look for if you don't have one now a brass can tap w yellow hose set up for cans. Helps if you have a place with a lot of stuff and can use retrofit adaptors with plumbing male union together and run little cans thru real gauges! Nice if you can do that - still can make that up.
Scream at the place with the crap can tap that wasted a can and get that $$ back and a new can for it too. Yes SUVA is the real stuff unless somewhere it states it has junk of any kind in with it.
True: Static 75 PSI static pressure is enough to allow compressor to get power to engage. Easy testing path of power where it's lost. Try from plug at compressor back or last relay or fuse forward and use an LED test light. Patch any pin prick (if needed to do) holes in wires with liquid electrical tape.
Try real hard to keep count of how many ounces are in the system as when this works real nice to know the right # for any future work.
I just don't have time or energy right now to write a total book on how to tweak a system to correct charge when variables are all over the place like this. Really - it can be done and I do it a lot for the unknowns - boats, RVs and assorted cobbled stuff, old stuff etc.
Good like with the help with this "Mike" person. Just may find the exact spot fast that's screwing up and worth it.
Keep at it. You'll get there. Do anything to try hard not to overcharge it when the time comes that it's engaged on its own,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 31, 2015, 12:18 PM
Post #22 of 65
(4677 views)
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To answer your question, yes go ahead and jump out the switch if that makes it engage until you have it fully charged and then replace the switch.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jjrbus
User
Jul 31, 2015, 1:51 PM
Post #23 of 65
(4673 views)
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Mobile Mike the AC guy showed up and here I am humiliated and embarrassed. I was shooting for my "Shade Tree Mechanic" certificate and I am back to the dunce cap.
I will tell you guys what was wrong, but you gotta promise not to tell anyone! One of the wiring harness connectors was together but not locked, just kinda hanging there looking like it was connected.
So anyway Mike put in one 12oz can of 134A and declared the system full. Nope he said that system is full, it needs no more. ????
The chart I have calls for 29oz if it were R12 and 26.5 for 134a. Plus the thermometer in the vent shows 70 degrees. Sure don't seem right to me?
So now I have a supposed 30 year AC pro telling me one thing and a chart telling me something else, what do I do now?
Jim
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Tom Greenleaf
Ultimate Carjunky
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Jul 31, 2015, 3:58 PM
Post #24 of 65
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70F output at center vent is wrong if system was on for a while and ambient temp just under about 120F! Sarcastic speak.
Probably a repeat. Converted from an OE R-12 system 134a takes less weight in ounces to fill the same area expressed as percentages of what is known if anything. I'll let you do the math.
If 29 oz was a known # for R-12 on a retrofit to 134a you would start at about 65% of that. Check performance after a while of running and even a spin around the block when first time changed over so oils get where they would be.
At say 80-90F you may see that it's putting out 50F+ with a raised idle and compressor might cycle? Now you would add 1-2 oz on the mark and take results again or up the percent to about 75% and it may end there. Outputs now reading mid 40sF with high fan on recirc, center vent still always. Lower fan speed one and temp drops a couple degrees. You are real close.
You might add 1 ounce now and slowly see output drop a couple degrees and stop there. All the time you are watching pressures vs actual incoming air temp and vent temps like a nut all this at once.
When you pass the sweet spot, exact right charge % performance drops off and might hear compressor struggle a bit. Now it a pest to get just that amount that is too much out. Said - do everything not to overcharge!
I don't know of any system that works properly when an exact amount is known to exceed 85% more common to be 80%.
The tweaking thing is pegging it to the 1/2 ounce on a 29oz system. Even with heat and humidity you could mess with it to put out high 30sF to low 40sF but it takes some time - at least more than the OE R-12 did when all was perfect. It will only have the output BTU of 80% of what R-12 had which is plenty for almost all if things are clean and working properly.
So what to do? This guy just blasted in more and happy with 70F isn't even conclusive yet. That could be because it's over the right amount so pressures are in order at what temp and RPM now by you.
Nice if you can get instant or at least fast temp results as they will change while sitting still long enough.
IDK - drive it for a day and get back to it. Keep a thermo in vent and watch at assorted speeds driving along,
T
(edit for link here about charging procedures)
http://autoforums.carjunky.com/..._A/C_SYSTEMS_P45460/
(This post was edited by Tom Greenleaf on Jul 31, 2015, 4:02 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Aug 1, 2015, 6:40 AM
Post #25 of 65
(4652 views)
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Curious, but what are the system pressures while it is running?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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