R12 to R134A conversion
06-21-2004, 01:12 AM
#16
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What kind of vent temps are you getting? I'm wondering (in wake of my recent high-pressure hose explosion and ensuing replacement) if I should just say "screw it" and convert to r134a. It's a hell of a lot cheaper than the r12.
06-21-2004, 09:06 PM
#17
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P-O-P,
I was getting about a 40 degree drop from outside temp after a few minutes. The early model always recirculates.
You blew a high side hose? Do you know how much pressure you were getting there? Do you think the hose blew because it was old? R134a runs at a higher pressure. Do you know if there is something wrong with the system?
Yea, I would convert if I were you. At least its only $4/can at Wally World.
I was getting about a 40 degree drop from outside temp after a few minutes. The early model always recirculates.
You blew a high side hose? Do you know how much pressure you were getting there? Do you think the hose blew because it was old? R134a runs at a higher pressure. Do you know if there is something wrong with the system?
Yea, I would convert if I were you. At least its only $4/can at Wally World.
06-21-2004, 11:09 PM
#18
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Yea, long story, but I ended up replacing virtually everything (including hoses) on the system except the high-pressure hose because (1) it looked okay / not diagnosed with any leaks and (2) I couldn't easily get it off the condenser (PITA, so I figured, just leave it and let the "if it ain't broke, don't fix it" mentality prevail).
The new Sanden compressor required me to cut the original end off and install a new elbow which gets clamped on. The clamp provided has a "spacer" on it to hold it a fixed distance off of the end of the hose (where it was cut), but what I think happened was that high-pressure freon got between where the clamp was and the "nipple" part of the new 90-degree elbow inside the hose, which extended into the cut hose about 2" past where the "spaced" clamp is. It looks like it ballooned the hose and just ruptured it right down the side - there's about a 6" long split right down the side, don't know how I didn't hear it go.
Anyway, I am a bit concerned about r134a because of the higher pressure and lower performance. I'm planning on driving this car to Phoenix and Las Vegas semi-regularly so it needs to have good a/c. Some r134a related questions:
(1) The oils for r12 and r134a are not compatible (so I've read). Since the system has r12 oil (and what's left of the r12 I suppose) in it, I obviously need to get vaccum pulled on it again once I get a replacement high-pressure hose. Will this get ALL the old oil out or do I need to drop the compressor again and drain it somehow?
(2) Where do the fittings go? My supposed "r134a conversion kit" that I bought had the compressor, mounting brackets, belt, hose ends, etc. but all the valves are for r12, not r134a (kind of irritates me that something sold as a "conversion kit" doesn't actually allow me to convert, but that's another story). How much do adapters cost and where could I find them? Paragon maybe?
(3) Once everything is vaccumed out, exactly how much oil and refrigerant do I add and how do I do this? I've never done it myself (just take it to the shop) but I don't mind learning and want to be sure I know how "just in case". But I also don't want to blow up the system or have a can explode in my face either. It seems like the advice is varied here on which connector to hook up to.
Thanks!
The new Sanden compressor required me to cut the original end off and install a new elbow which gets clamped on. The clamp provided has a "spacer" on it to hold it a fixed distance off of the end of the hose (where it was cut), but what I think happened was that high-pressure freon got between where the clamp was and the "nipple" part of the new 90-degree elbow inside the hose, which extended into the cut hose about 2" past where the "spaced" clamp is. It looks like it ballooned the hose and just ruptured it right down the side - there's about a 6" long split right down the side, don't know how I didn't hear it go.
Anyway, I am a bit concerned about r134a because of the higher pressure and lower performance. I'm planning on driving this car to Phoenix and Las Vegas semi-regularly so it needs to have good a/c. Some r134a related questions:
(1) The oils for r12 and r134a are not compatible (so I've read). Since the system has r12 oil (and what's left of the r12 I suppose) in it, I obviously need to get vaccum pulled on it again once I get a replacement high-pressure hose. Will this get ALL the old oil out or do I need to drop the compressor again and drain it somehow?
(2) Where do the fittings go? My supposed "r134a conversion kit" that I bought had the compressor, mounting brackets, belt, hose ends, etc. but all the valves are for r12, not r134a (kind of irritates me that something sold as a "conversion kit" doesn't actually allow me to convert, but that's another story). How much do adapters cost and where could I find them? Paragon maybe?
(3) Once everything is vaccumed out, exactly how much oil and refrigerant do I add and how do I do this? I've never done it myself (just take it to the shop) but I don't mind learning and want to be sure I know how "just in case". But I also don't want to blow up the system or have a can explode in my face either. It seems like the advice is varied here on which connector to hook up to.
Thanks!
06-22-2004, 12:39 AM
#19
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P-O-P,
Sorry that the hose blew and dumped the R12. I remember reading your post about the new compressor kit. I agree that the kit should come with R134a fittings and instructions to install them. The fittings are cheap, and the vendor could have included a set for a few dollars.
I'm not an A/C expert. Kevin Baker is. Maybe he can help.
Anyway, here are the answers to your questions as far as I know.
1) R12 systems use mineral oil. R134a systems use PAG or POE (ester) ester oil. The oil actually dissolves in the refrigerant. Manufacturers use PAG oil on new systems, but ester oil is recommended for systems that were originally charged with R12/mineral oil. Use POE 100.
Pulling a vacuum on the system will not remove the oil. Empty the oil from the compressor into a container so that you can measure the amount and fill the compressor with the same amount of POE 100 oil. You need to rotate the compressor shaft by hand a dozen times to assure the oil lubricates the compressor. You'll also need to replace the drier again, so i'd put a couple of ounces of POE 100 oil in there, too.
Apparently there is no problem with leaving the mineral oil in the system, but it will not lubricate with R134a so you need the POE 100 oil.
2) The conversion fittings go on the low and high side ports. I don't know which port is which on your car, but on my 83 with the ND compressor, the low side is on the compressor and the high side is near the drier. You should check the Sanden documentation to determine which port is the low side it the compressor has two ports. You should be able to get the adapters at any auto parts store. They cost about $7-10 for a set.
3) I bought an eight ounce bottle of POE 100 oil. Of course, when you pour the oil in the compressor, you need to add the oil and connect everything back up before you pull a vacuum. Actually, you could connect the system back up and buy some of those cans of "oil charge" that add oil and R134 at the same time. I needed 4 ounces in my ND compressor.
As far as pressures, the high side pressures probably aren't that much higher for R134a. But the low side should be about 40 psi wich is about 10 psi higher than R12.
As far as performance is concerned, the R134a works pretty well. The condensors in 944 are pretty large, which I think they work well with R134a. Other cars with smaller condensors may have problems. The main difference I noticed was that the R134a didn't seem to cool as well at idle. Works fine when the car is moving. I've noticed this with my wife's Subaru which came with R134a, too.
My system had 16 ounces of R12 when I had it recovered. With that low charge, I would get cool air and the car never really cooled down. After I converted to R134a, I could get in my car which had been sitting in the sun all day in 90 degree weather with an interior temperature of 110 degrees. The system would be blowing 60 degree air in 5 minutes and the car would be cool in 10 minutes.
Good luck.
Sorry that the hose blew and dumped the R12. I remember reading your post about the new compressor kit. I agree that the kit should come with R134a fittings and instructions to install them. The fittings are cheap, and the vendor could have included a set for a few dollars.
I'm not an A/C expert. Kevin Baker is. Maybe he can help.
Anyway, here are the answers to your questions as far as I know.
1) R12 systems use mineral oil. R134a systems use PAG or POE (ester) ester oil. The oil actually dissolves in the refrigerant. Manufacturers use PAG oil on new systems, but ester oil is recommended for systems that were originally charged with R12/mineral oil. Use POE 100.
Pulling a vacuum on the system will not remove the oil. Empty the oil from the compressor into a container so that you can measure the amount and fill the compressor with the same amount of POE 100 oil. You need to rotate the compressor shaft by hand a dozen times to assure the oil lubricates the compressor. You'll also need to replace the drier again, so i'd put a couple of ounces of POE 100 oil in there, too.
Apparently there is no problem with leaving the mineral oil in the system, but it will not lubricate with R134a so you need the POE 100 oil.
2) The conversion fittings go on the low and high side ports. I don't know which port is which on your car, but on my 83 with the ND compressor, the low side is on the compressor and the high side is near the drier. You should check the Sanden documentation to determine which port is the low side it the compressor has two ports. You should be able to get the adapters at any auto parts store. They cost about $7-10 for a set.
3) I bought an eight ounce bottle of POE 100 oil. Of course, when you pour the oil in the compressor, you need to add the oil and connect everything back up before you pull a vacuum. Actually, you could connect the system back up and buy some of those cans of "oil charge" that add oil and R134 at the same time. I needed 4 ounces in my ND compressor.
As far as pressures, the high side pressures probably aren't that much higher for R134a. But the low side should be about 40 psi wich is about 10 psi higher than R12.
As far as performance is concerned, the R134a works pretty well. The condensors in 944 are pretty large, which I think they work well with R134a. Other cars with smaller condensors may have problems. The main difference I noticed was that the R134a didn't seem to cool as well at idle. Works fine when the car is moving. I've noticed this with my wife's Subaru which came with R134a, too.
My system had 16 ounces of R12 when I had it recovered. With that low charge, I would get cool air and the car never really cooled down. After I converted to R134a, I could get in my car which had been sitting in the sun all day in 90 degree weather with an interior temperature of 110 degrees. The system would be blowing 60 degree air in 5 minutes and the car would be cool in 10 minutes.
Good luck.
