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AC Retrofit - Questions on Oil Type/Amount 200 1992

posted by cn52x5hg on Fri Nov 11 10:44 CST 2016
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last visit: Sat May 11 17:37 CST 2013

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Hi Folks,
I'm in the process of retrofitting my AC to R134a. This is my first AC project, so learning a lot. I ordered the Volvo retrofit kit as well as a new compressor. I've removed and flushed everything and am replacing all of the o rings. I've got to the point of installing the new compressor and have a few questions about the oil type and amount.

1. The 700/900 FAQ specs out 200 ml of ester oil loaded directly into the new compressor. When I ordered the compressor I also ordered some PAG oil with dye. I'd prefer to use the PAG w/dye oil for troubleshooting down the road. Since everything else was flushed and I have a new compressor, can PAG be used?

2. The 700/900 FAQ retrofit procedure calls out 200 ml of oil filled directly into the new compressor. This amount aligns with the label on the original Volvo compressor which also states 200 ml. Since the retrofit procedure doesn't include removal and flushing of all components, is the assumption that some amount of oil will be left in the system and that the total amount of oil needed in the system is more than 200? Since I removed and flushed the old oil out of all components, do I need to accommodate for this by adding more oil than is specified on the compressor label? My new compressor label states 150 ml. To further complicate, things I found a document on the Hella website which has specs for the 1993 240 R134 system, and it lists 220 ml of PAO oil. I am wondering if the entire system needs 220 ml in order to guarantee there will be enough in the compressor at any time?

Thanks!

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AC Retrofit - Questions on Oil Type/Amount 200 1992

posted by Amarin on Sat Nov 12 18:44 CST 2016
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last visit: Thu Oct 23 22:42 CST 2014

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Yes you could use 100% PAG as you have flushed the old mineral oil out. That amount would be 220ml as stated for 1993 240 series specs for fresh system installation.

Ester oil is not needed in your case. Ester is only used in case of no flushing was done as it could mix well with any left over mineral oil in the system. PAO oil is what Hella's recommendation of their product instead of using the usual mobile AC standard PAG. Hella doesn't produce any PAG oil if I remember correctly. R134a by itself could be used with PAO, POE, Ester and PAG oils in different applications (eg. home refrigerator/freezer) but for mobile AC PAG oil is the industry consensus.

Also drain out your new compressor of any oil. Most compressor is shipped with oil inside but you don't need that oil as it could be pre-filled with ester oil. In case of it was filled with PAG oil it could be of different grade than needed by your system. So drain it all out by undoing the small drain bolt and tip the compressor upside down to let oil drain from the suction/discharge ports. Install back the drain bolt and tighten it - just snug is enough. Fill back the compressor with your new PAG oil. Usually 100ml is about enough. Fill your new oil thru the suction port only (not thru the drain hole). Spin the compressor clutch by hand at least 15 times (this is an IMPORTANT step) to let the new oil get to work inside compressor. Your compressor could hydrolock and damage its inside if you missed this step. Pour the rest of the 120ml oil into your accumulator/dryer, condenser and evaporator. Exact amount for each component doesn't matter as the oil will get circulated when the system works and balance itself out in the system.

If there's still time get yourself a double-end capped (DEC) PAG oil (the latest in today's specs) which is more stable with less moisture absorbing properties compared to just a PAG oil. PAG oils also come in different viscosities PAG46, PAG100 and PAG150. Most Volvo compressor uses PAG46 viscosity for Zexel/Diesel-Kiki/Seltec type compressor and PAG100 for Sanden type. Look at compressor label for manufacturer's name.

Disregard the 150ml label on the compressor as the compressor could be originally intended for a particular vehicle's AC system but it (the compressor) could still be used in most other vehicles with different system oil capacities.

What you have to also realise is that other than correctly using the amount of oil in the system, the amount of refrigerant charge is equally important as it's the refrigerant (R134a) that carries/pushes the oil all over the system. Undercharging could shorten the life of the system even with adequate oil inside. So always charge by refrigerant weight to ensure adequate charge.

Regards,
Amarin.

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AC Retrofit - Questions on Oil Type/Amount 200 1992

posted by cn52x5hg on Wed Nov 16 10:37 CST 2016
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Amarin,

Thanks for the comprehensive response. Unfortunately I moved forward on a slightly different approach before seeing your response. I used Behr PAO oil as this was recommended by FCP, where I bought the compressor. I decided to use 200 ml per the Volvo procedure on the FAQ, and I filled this via the drain hole (after draining the oil that came with the compressor), also per the Volvo procedure. I did turn the compressor by hand 10 to 15 times, so I'm hopefully good there. I did not charge the system yet, so I may open up the receiver/dryer add another 20 ml of oil.

One interesting and annoying thing that I ran into was that the final piece of the retrofit kit (pipe with R134 port between receiver/dryer and evaporater) didn't seem to have compatible threads with the evaporator!!! I tried it about 10 times before reverting to the original pipe which threaded on perfectly. So I'm hoping I can get some sort of adapter for the R12 port on the old pipe to support an R134 connection. After complete disassembly, cleaning, and reassembly of everything in the system, it was discouraging to have this not fit. It seems like the Volvo kit expected an evaporator with different threads. This prevented me from applying a vacuum to the system to test the connections as my gauge set has R134 connectors.

If I can get an adapter I hope to apply a vacuum to evacuate the system and test for leaks this weekend. At the end of the day this job was not as difficult as I feared. The hardest part was getting the compressor in and out. This was mostly due to difficulty of access to the nuts on the hoses on the compressor. On reassembly I realized that if I loosen up the AC mounting bolts/nuts that I could swing the compressor enough to get a wrench on the nuts. Also, I ended up removing all of the intake hoses up to the throttle body to get access.

Thanks again for the advice.
-Kevin

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by Amarin on Thu Nov 17 12:42 CST 2016
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last visit: Thu Oct 23 22:42 CST 2014

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If you have to use back the old connecting pipe then keep using it.

For the old R12 port there is an adaptor available to convert low pressure R12 port into a low pressure R134a port. Such adaptor screws itself onto the R12 port and the conversion is instant/immediate. But BEFORE that you must remove the old valve core inside the R12 port using a valve core tool. This tool is an extra buy.

See here:
http://www.shopcenturyautoair.com/store/p66/Standard_Valve_Core_Tool_FJC_2745.html

Some valve cores were screwed-in so tight that it is wise to get such tool for its removal. The new R134a retrofit port have its own valve core (with R134a compatible rubber seal) already installed.

See here:
http://www.shopcenturyautoair.com/store/p61/Retrofit_Fitting_Lowside_1%2F4%22_Port_CP0109.html

Just for your info there are low pressure R12 port and high pressure R12 port. Each have different sized threads and they are not interchangeable. Be sure to get yourself a blue capped R134a retrofit adaptor port as pictured in the link above.

Regards,
Amarin.

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by cn52x5hg on Fri Apr 7 09:07 CST 2017
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last visit: Sat May 11 17:37 CST 2013

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A few other projects got in the way of completing this, but I finally got back to it and with the help of some nitrogen pressure testing found the leak that was causing my vacuum test to fail! It's finally time for the R134 fill. When searching around for how much R134 to charge the system with, all I could find was a Hella document that listed 750g of refrigerant as the capacity of the system. I was hoping to confirm this was the right amount? Having never done this before, any tips on loading the R134 would be appreciated (should the compressor be running when loading the R134?).

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by Amarin on Fri Apr 7 10:45 CST 2017
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last visit: Thu Oct 23 22:42 CST 2014

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Tips on loading R134a:

Quick outline:
You start with the system still in vacuum after vacuuming. Connect your R134a container. ENGINE OFF. Start refilling until there's no more vacuum. This usually takes about 100g to 120g of R134a. Then find your low pressure switch and short the its two terminals together at the electrical connector. Start the car and AC. Now the compressor is RUNNING. Continue refilling till you've achieved about 750g. Stop AC and disconnect container. Remove the shorting wire and connect back low pressure switch as normal. Start using the AC.

Several notes here:
1. Its best to use proper AC manifold gauges in doing refilling so that you don't break the already established vacuum condition. If you're using quick refill bottle you might let some air in when disconnecting the vacuum pump AND when connecting the quick refill bottle. After the first bottle is emptied you continue with another bottle until the targeted weight is achieved but this time there's no more risk of letting air in as the system pressure is already above atmospheric air pressure. If you're quick in disconnecting and reconnecting maybe just a little air goes in which is negligible. When lots of air accidentally goes in ICE (from water vapour in air) could form at the AC expansion valve causing less cooling AC later.

2. In using AC manifold gauges you could disconnect the vacuum pump (yellow hose) at the pump after shutting off both valves (blue & red knobs turn clockwise). Then switch the yellow hose to a R134a tank (typically a 30 lbs R134a tank). Loosen the yellow hose connection at the manifold. Now open a bit the valve at the R134a tank to purge air off that yellow hose. Air would be purged at the loose connection at manifold. After 1 or 2 seconds tighten the yellow hose's connection at the manifold. Now no more air within yellow hose. The tank should be sitting upright (this means vapour charging) on a weighing scale. Using digital scale is better. ENGINE OFF. Zero the scale then slowly open the blue valve at manifold to start refilling. You'll see weight reduction in grams. Refill until the system has no more vacuum. Shut the blue valve, start the car, short the low pressure switch then switch ON the AC. It doesn't matter if blower air is low or high as you're charging by weight. Open back the blue valve and continue refilling until 750g is achieved as displayed on scale. Shut the blue valve.

3. If you're using AC manifold gauges NEVER OPEN THE RED VALVE during refilling. The high pressure from compressor would re-route thru manifold to your R134a tank and cause EXPLOSION. Use some masking tape or red electrical tape as marking on the red valve. USE ONLY THE BLUE VALVE.

Regards,
Amarin.

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by cn52x5hg on Fri Apr 7 16:24 CST 2017
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Thanks Amarin for this detailed procedure! I have a proper manifold gauge set, but was going to refill from the small 12 oz canisters sold at the auto parts store. It's looking like yellow hose I used between the pump and manifold for pulling the vacuum is a different size/thread than these canisters. Is this typical? Looking like I'm going to need an adapter?

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by cn52x5hg on Fri Apr 7 17:02 CST 2017
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It looks like one of these in my future

http://www.mastercool.com/product/85510/

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by Amarin on Fri Apr 7 18:19 CST 2017
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last visit: Thu Oct 23 22:42 CST 2014

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Yes. That Mastercool can tap valve is made for your purpose. There's a pin within the tap valve to puncture the top of the can. The tap valve's male ACME connector should fit well into the female ACME connector of your yellow hose. As I refer back to earlier posting you're using R134a manifold gauge set, so no problem here.

As you're using 12oz cans you'd need to purge air off the yellow hose every time you connect a new canister then continue refilling. To achieve 750g you'd need to use 2 full cans with the last can 1/6 emptied (which is about 70g emptied). For this you could weigh the last can together with the tap valve installed (minus the yellow hose). After finished refilling weigh again to know how much has spent.

This LAST STEP is for more accurate refilling. There are still unused/leftover R134a remain in your manifold hoses which DOESN'T go into the system but has left the can. You might need to account for these "dead space" losses. So add about 60g more (estimation: 3 ft of blue hose contains about 5g of R134a VAPOUR, 3 ft of red hose about 50g of LIQUID R134a from compressor and 3 ft of yellow hose 5g of R134a VAPOUR). In other words the last can should be 70g plus another 60g emptied which TOTALS around 130g emptied/lighter (before disconnecting the hoses at low & high pressure ports of the AC system).

Regards,
Amarin.

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by Amarin on Sun Apr 9 07:49 CST 2017
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I meant to say you'd need to use 3 cans in total with the last third can only 130g emptied.

Regards,
Amarin.

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Such retrofit adaptor is available (R12 low pressure port into R134a low pressure port) 200 1992

posted by cn52x5hg on Tue Apr 11 17:59 CST 2017
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Thanks Amarin! I am going to give it a shot this evening. I'm happy to see that my system has held its full vacuum for 3 days now without budging. Good tip about accounting for the gas left in the hoses that has left the can but not got into the system. I will be filling mine only via the low side blue hose (no high side connector on my compressor or elsewhere), so will accommodate for that.

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