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wmsue

Retrofit R-12 to 134A - what about the oil?

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I'd like to get the AC working for next summer and wanted to get a head start on it now.

 

I'm installing a new (4 seasons) compressor, drier, POA cycling valve, and flushing the entire system on my 65 Buick Electra

The old R-12 system took 4.25 lbs , so I'm going to start with 3.75 lbs of R-134A

But what about the refrigerant oil? My new 134A compressor came with a 3 oz. charge. My original service manual states that the factory compressor should have 10.5 oz of oil.

I checked on the website for 4 seasons and they say to either : refer to factory manual, check the tag on the compressor. and use a PAG oil. Not how much. Or even which PAG oil.

I haven't checked with 4 Seasons directly yet, but wanted to post the questions here.

 

So I ordered PAG 46 for R134A oil charge 2 oz. along with a few more quarts of flush to thoroughly clean everything. Should I get enough PAG oil to reach 10 oz.?

 

Since one would generally work on A/C units when the temp is higher, and the temps here are in the 30's right now , I was going to replace parts, flush the A/C system, pull a vacuum on the system, place the oil charge in the system, and put it on hold till I get a warmer day to actually put the remaining R134A. Does this sound like a plan? Any changes to consider?

 

Thanks

 

Bill

 

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I have converted Hundreds and Hundreds of cars back in the late 90’s and early 2000’s. At first they insisted on changing the oil. When it was discovered you could do it quick and dirty..........and just change the fittings and  orifice  tube that’s what all the shops did. We usually didn’t change out the accumulator or receiver drier either.....it would be best, but most people wouldn’t  pay for it. The gas has a smaller molecule so it leaks or seeps from the old style hoses......thus, in a perfect world, make all new modern lines and crimps and the system will stay tight........otherwise fill it every year. 

Edited by edinmass (see edit history)
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10 hours ago, edinmass said:

I have converted Hundreds and Hundreds of cars back in the late 90’s and early 2000’s. At first they insisted on changing the oil. When it was discovered you could do it quick and dirty..........and just change the fittings and  orifice  tube that’s what all the shops did. We usually didn’t change out the accumulator or receiver drier either.....it would be best, but most people shouldn’t pay for it. The gas has a smaller molecule so it leaks or seeps from the old style hoses......thus, in a perfect world, make all new modern lines and crimps and the system will stay tight........otherwise fill it every year. 

 

 This is what I was told by an old time AC man that is still in business. Did my '92 Buick that way. 

 

  Ben

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So NEW HOSES would be the best way to go. Since they are 50+ years old, it makes sense since I've got a fair amount of $$ already invested.

 

Who sells AC hoses for a 50+ year old car? I see kits available on the internet but the fittings aren't anything like mine. Can I reuse my ends and just get new hose?

I checked with Carid, but said they did not have the hose. I did find on their webpage an adapter for the compressor plate that could work if I could find the proper hoses and ends. the plate had 1"-14 threads.

 

I remember making hydraulic hoses when I worked in a machine shop 40 years ago, We had Weatherhead hose and a huge supply of different fittings that we'd crimp onto the hose. But we could never reuse the old fittings.

 

Robert, thanks for the info on Nylog Blue. I've never used it before, but will use now.

 

Thanks

Bill

Edited by wmsue (see edit history)

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It would help to know a bit more. Is your new compressor a stock A-6 style or a modern smaller Sanden? Most new R134A compressors come filled with PAG oil in the correct amount for the compressor size. Generally if you do a total flush job on the evaporator and condenser you would add a couple ounces of PAG oil to each and that would suffice. Don't waste your time with oil charge cannisters, in my experience they don't work well and it is hard to keep track of how much is going in - you don't want too much oil. As for hoses, if you had a system that still held an R-12 charge you can probably reuse them but change out the old O-rings for the new green 134 compatible ones. It is actually quite easy to make new hoses though and the components are available from many sources, the difficult part is that you have to crimp them together but many shops can do this for you for a fee. I would not do partial assembly then leave it sit, wait for better weather and do the whole job at one time. Lastly, with R134 it is better to charge based on pressure rather than weight. Use a good quality gauge set, start with a minimum charge and let the target pressure determine full charge based on the ambient temp when charging.

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3 hours ago, TexRiv_63 said:

I would not do partial assembly then leave it sit

 

Sounds like he is doing a partial charge, not a partial assembly. OK to complete assembly, check for vacuum leaks (if no hurry, let it sit under vacuum for 12 to 24 hours) then fill with some R134a (say a can or two) and wait for warm day to top off charge. If not replacing accumulator/drier, then place heat lamp on it to get it up to about 150°F to boil out the moisture in the desiccant while under vacuum.

 

I pour out the oil in a fresh compressor and measure it (says so in every compressor instruction sheet I've seen. Don't do it and warranty can be denied for not following instructions). I use a pill bottle of about a fluid ounce. Four Seasons should answer question of how much and viscosity rating oil for compressor then I add an ounce for every large part I flushed clean (condenser, accumulator, evaporator). Never used oil charge, just pour it in the compressor hoses before hooking them up. Oil comes in small bottles. Rotate the compressor shaft to make sure it didn't lock up.

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I don't remember the name . but a few years ago I typed in a/c hoses for 1963 Pontiac and found a supplier. Try that but put in the make and year of your car.

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Sometimes things just aren't simple, especially if you overthink the problem. I think that's what I do at times.

My new compressor is an A6 style exactly like the original but compatible with 134A. It came precharged with 3oz of PAG oil.....but the instructions say to check to be sure to add the recommended amount and type to the compressor. I tried to scan the QR code but the pdf would not load so I went directly to the 4 seasons resource page and still did not get an exact answer. A phone call to 4 seasons will happen tomorrow. 4 seasons show a chart online that has quantity and type of oil for lots of cars, but not my Buick.

 

My confusion is how much oil and which type of PAG oil to add. 4 seasons says to refer to your original manual if needed. My original service manual states that 10.5 oz are needed.

If I add the oil to the compressor before I evacuate the system, won't I lose all the oil when I pull a vacuum on the system?

In the past I've always added a can of precharged oil and the required refrigerant and used my gauges. And was good to go.

 

I've worked on AC systems that would not work properly when the ambient temp is low. If my system is similar, then I can't get a proper reading?  Correct?

 

I will call 4 Seasons this week and hopefully get a better answer. And update the post.

 

thanks for all the replies and help.

It's truly appreciated.

 

 

Bill

 

AC manual 1.jpg

AC manual 2.jpg

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7 hours ago, wmsue said:

If I add the oil to the compressor before I evacuate the system, won't I lose all the oil when I pull a vacuum on the system?


No! It will be fine. This is how every system (car home commercial) is charged In the beginning. Oil in, finish assembly, evacuate, add refrigerant. 

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Yes, it is hard to get good pressure temperature readings when the ambient temperature is below typical operating temperatures. You can always heat the condenser and warm the refrigerant cans. Shop manuals used to show this being done.  You ought to try filling heat pumps when the outside temperature is below 40F. You must heat the refrigerant bottle, as it goes really cold when refrigerant is removed (that’s how ac works......)😉

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I would make all new lines....that being said, the entire job is rather lengthy and expensive to do correctly. In a perfect world a new receiver dryer, new lines, orifice tube, compressor, ect. Flush entire system to be sure it clean. When you add it all up, lots of time and money. That’s why so many are done “quick and dirty”, and people just add gas every year. Filling it on pressure is the correct method. What is the application? Year, make, model? 

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I recently did a rather extensive A/C retrofit successfully on my 66 Dodge Monaco wagon and posted the process here. While not exactly the same as what you are doing many of the processes are similar, take a look:

 

 

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Your write up looks very detailed and concise. I read through it last night Thanks Don and everyone else.

 

I did call 4 Seasons and I need to add 8 oz. of PAG 150 oil to the reservoir to get a total of 11 oz. before pulling a vacuum. I guess I won't lose all the oil when I evacuate and pull a vacuum.

I guess there's lots more to do before I can wrap it up. I'd like to do a good rebuild and not half a##, so a lot more time....and $$ of course.

 

Found a new defroster door vacuum and got it ordered. I also ordered a partial wire harness for the blower motor. The old one was melted. 4 weeks delivery time.

After removing the AC hoses I'm going to look at replacing them. A few options but will probably have to send them to the vendor and have new hoses put on. The ends and metal tubing are unique and not readily available.

 

Like Don (TexRiv_63) said in his rebuild post is so true.....  " It never fails, I started thinking I would just replace the parts.. then I decided to do a little cleanup and maybe some touchup paint.. then I removed the grille to get more room to work.. then I took off everything on the front of the motor.. now I will be taking off everything loose, cleaning most everything under the hood and detail painting the engine before installing the new a/c stuff. Never fails...

 

I'll be working on a lot of the under the hood details and cleaning things up. The inner fender and firewall are at the top of the list.

 

This repair job started when I was checking the manufacture date on my tires. After finding  they were 9 years old, I kept looking at the hoses, belts etc. and here I am.

I'm not buying the tires till spring, so I have lots of time to find other things to replace.

 

Bill

 

 

Edited by wmsue (see edit history)
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Update,

Sent the 4 old A/C hoses off to a vendor in Florida and in about a week I had them back with new hose installed with my old hose ends. They cut off the metal and brazed them to new crimpable ends. Very professional job. I had a bit of trouble with alignment of 1 hose connection to the expansion valve, but overall a good job.

New compressor, dryer, POA valve, expansion valve, hoses, and a thorough flush of the entire system.  It took 3 quarts of flush to be sure everything was clean. The condenser was replaced a year or so ago when I tried to fix the AC. It just needed a flush. I pulled a vacuum for 12 hours and let it stand for 24 hours. No leaks. The green orings and nylock seems to have done the trick.
Just have to have a warmer day to add R134. I don’t have heat in the car half of my shop. A bit too cold for that job today, but Friday the temps may get to the mid 50’s.

Here’s a photo with everything installed. Just some more cleanup needed.

 

I’m also going back over some little things that need attention......door jamb switch, glass alignment between doors and convertible top, power seat switch, Maybe it’s time to look at getting some led lights for the courtesy lights too.
 

thanks for all the help and suggestions 

 

Bill

 

 

11D4D376-1B0C-48EC-BA55-441BD0374ED2.jpeg

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On ‎1‎/‎7‎/‎2020 at 9:03 PM, wmsue said:

Update,

Sent the 4 old A/C hoses off to a vendor in Florida and in about a week I had them back with new hose installed with my old hose ends. They cut off the metal and brazed them to new crimpable ends. Very professional job. I had a bit of trouble with alignment of 1 hose connection to the expansion valve, but overall a good job.

Bill

 

Bill,

Who did you use in Fla?
 

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I used ColdHose Products.

Their info is below. They quoted me a price before beginning work and had a fast turnaround time. This is not the typical A/C repair weather so I didn't expect to wait weeks and weeks.

 

I'm waiting for better temps and then I'll charge the system with R-134.

 

Good Luck

 

Cold Hose.jpg

Edited by wmsue (see edit history)
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I worked for many years in Ford's Climate Control Division HVAC lab.  When we got a compressor to test we drained the oil in a Nalgene graduated beaker,  then added enough oil to the beaker to make up the difference in the required oil amount and poured it back into the crank case  of the compressor before installing it.  This was done for a new or completely flushed system and we always used new receiver driers and accumulators if the accumulator had an internal filter.  Then we pulled a brief vacuum and checked of leak under vacuum (gauge creep), then a vapor charge was added and a pressure leak test was performed with a leak detector.  If the system passed the leak tests we put Mr. Welch vacuum pump to work for at least an hour to pull a micron vacuum to make sure the system was completely free of moisture, then the charge was added.   That was in the 70's and 80's and R-134A was just coming out by the time I left the lab for a job in the engineering office.

Edited by Str8-8-Dave
add detail (see edit history)

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2 hours ago, wmsue said:

I used ColdHose Products.

Their info is below. They quoted me a price before beginning work and had a fast turnaround time. This is not the typical A/C repair weather so I didn't expect to wait weeks and weeks.

 

I'm waiting for better temps and then I'll charge the system with R-134.

 

Good Luck

 

 

I also used Coldhose for a lot of stuff on my conversion, good quality and nice to deal with. 

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