variable orifice tube ?

Booyah45828

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Blackdawg beat me to it, but if there isn't refrigerant in the system, the compressor clutch shouldn't engage and won't be turning the compressor innards. No need to remove the belt on an empty system.

Any time I add oil to a dry system, It's typically half in the compressor, half in the accumulator/receiver drier. The compressor is the only item that needs lubricated, so oil should definitely be added to it, but I've seen instances where people added the total system oil volume into the compressor and then destroyed it at first start because of slugging. They're not really made to pump liquids.

With r134a, a good long vacuum is necessary. I've gone an hour plus on humid days. It can take a while to boil out a system and you want zero water in there. Also make sure to use a good vacuum pump and you can suck down to within 1 inhg of your current barometer. If it can't do that, you have a bad pump or a leak that needs to be found.

Also, I've used variable orifice tubes with success, but they've always been with systems that were cleaned spotless.
 

franklin2

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I thought he was going to inject the oil through the ports with cans of oil made to hook to the service ports/gauge set. You would have to run the compressor for it to suck the oil into the system. I was afraid it would lock up before it got enough oil to be safe. This works if there is old r12 oil still sitting in the compressor.
 

jericho

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Sorry for the confusion, I purchased the estor oil in bottles' to be poured into the individual parts. I'm still not sure of the total oil though. It seems somewhere between 7 to 10 oz. I've read on various threads, but a lot of discussions were of systems older than mine, 80's and pre '93.
 

jericho

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How far are you from me? I can do the final vacuum boil and refill for you (free, just pay for the refrigerant) if you want so you can charge system rightwright no air and pull in ester oil instead of the cans
Thanks so much for the offer, I'm 90 miles east from what is now "Escape from New York" City lol. I was going to pour the oil into compressor, receiver/dryer and evaporator (total amount I'm not sure yet) after flushing out, then vacuum. I do have a good vacuum pump so should be ok. I gotta figure the total oz. of r134a then I hope we're good to go!
 

Danielle

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Yes the cans from auto parts stores will get a charge going and manually filling a bone dry system is best way to go. Even with a machine, that's recommend.
But I don't know how much moisture can be boiled out and how much of a vacuum can be obtained with these diy kits since how long can you hang out at vacuum? I've never tried a diy kit.

It does sound like you've done as much research as can be done with a 30 year old vehicle being converted to technology that wasn't even invented when that truck was put out to market.

One ofmy trucks is r12 so I will be riding on your coat tails of research when my system fails to convert haha so I do thank you for doing all the hard work for me. I just hope I have some more time before I'm in this position.
 

Booyah45828

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Prodemand says 7 oz of oil and 44 oz of R12 for an f-series truck. Charge 85-90% of that with r134a.
 

aggiediesel01

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aha, 1993 factory air was 2 lbs, 12 oz. of r12 . So I should charge 15% less of r134a?:Thumbs Up

So that's 44oz x .85 =37.4oz

That matches almost exactly with the factory 134 systems which was 38oz per ford spec w/ the slightly larger condenser.

And if you use the oil replacement recommendations from the ford TSB, put 3oz in the compressor, 3oz in the evap, 1oz in the condenser, 2oz in the accumulator, that's 9 total.

Oil is going to mostly settle and stay in the accumulator (particularly here b/c the oil collects and stays trapped in the desiccant bag) and compressor. I prefer to err on the less oil side than more b/c the oil is an incompressible and takes the place of refrigerant making the system less efficient trying to achieve the correct fill in the evaporator. Since the recommended above says 7oz (it's not described if that's what should be added for just an evac and refill or if that's for a complete dry system) and Ford adds up to 9, I would go with using 8oz divided as proscribed among the components leaving out the condenser.

Run the vacuum for as long as you can stand waiting. I've left it running over night before when I finished component replacement late in the evening. Usually 30min is enough but an hour or longer is better. I also don't like to just fill the system with refrigerant per spec. I use it as a target but I try to run as little refrigerant as possible to achieve as low a vent temp as possible (I target 36-38deg) since high side pressures can get out of hand easily down here in the high humidity heat. It risks freezing the evap in the spring and fall but that's only about 2 weeks out of the year for us and to be honest it hasn't happened enough for me to notice, and then we don't use a/c for a couple months and after that it's back to hot.

When filling, I like to get it close and then take the vehicle for a drive for 15-30 min to give the system a chance get the heat out of the interior and stabilize and to see how it is behaving in real conditions. Then pull it back in and do a final adjustment, fill or recover.

To each his own but I've had success with what I do and they last for a long time, at least a few years before needing more refrigerant added again.
 
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IDIBRONCO

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and then we don't use a/c for a couple months and after that it's back to hot.
I've been in Cypress between Thanksgiving and Christmas and I'll agree with that. While I thought the weather was nice the others I was with thought it was freezing. The night I left, I was driving around with the windows down while leaving Houston.
 

jericho

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So that's 44oz x .85 =37.4oz

That matches almost exactly with the factory 134 systems which was 38oz per ford spec w/ the slightly larger condenser.

And if you use the oil replacement recommendations from the ford TSB, put 3oz in the compressor, 3oz in the evap, 1oz in the condenser, 2oz in the accumulator, that's 9 total.

Oil is going to mostly settle and stay in the accumulator (particularly here b/c the oil collects and stays trapped in the desiccant bag) and compressor. I prefer to err on the less oil side than more b/c the oil is an incompressible and takes the place of refrigerant making the system less efficient trying to achieve the correct fill in the evaporator. Since the recommended above says 7oz (it's not described if that's what should be added for just an evac and refill or if that's for a complete dry system) and Ford adds up to 9, I would go with using 8oz divided as proscribed among the components leaving out the condenser.

Run the vacuum for as long as you can stand waiting. I've left it running over night before when I finished component replacement late in the evening. Usually 30min is enough but an hour or longer is better. I also don't like to just fill the system with refrigerant per spec. I use it as a target but I try to run as little refrigerant as possible to achieve as low a vent temp as possible (I target 36-38deg) since high side pressures can get out of hand easily down here in the high humidity heat. It risks freezing the evap in the spring and fall but that's only about 2 weeks out of the year for us and to be honest it hasn't happened enough for me to notice, and then we don't use a/c for a couple months and after that it's back to hot.

When filling, I like to get it close and then take the vehicle for a drive for 15-30 min to give the system a chance get the heat out of the interior and stabilize and to see how it is behaving in real conditions. Then pull it back in and do a final adjustment, fill or recover.

To each his own but I've had success with what I do and they last for a long time, at least a few years before needing more refrigerant added again.
This is all great advice, and I agree the 8oz sounds like a smart compromise for oil. I also think less is more when it comes to the refrigerant charge. I've heard pressures rise too high with overcharging and things quickly go bad, so I'll fill slowly. I will leave the vacuum on for a few hours at least to get the moisture out. All this valuable information has given me the missing details so I can move forward.
 

jericho

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Yes the cans from auto parts stores will get a charge going and manually filling a bone dry system is best way to go. Even with a machine, that's recommend.
But I don't know how much moisture can be boiled out and how much of a vacuum can be obtained with these diy kits since how long can you hang out at vacuum? I've never tried a diy kit.

It does sound like you've done as much research as can be done with a 30 year old vehicle being converted to technology that wasn't even invented when that truck was put out to market.

One ofmy trucks is r12 so I will be riding on your coat tails of research when my system fails to convert haha so I do thank you for doing all the hard work for me. I just hope I have some more time before I'm in this position.

Well the kit I got was really just the basics for converting if the compressor is bad: 1 compressor 2 o rings 3 receiver /dryer 4 orifice tube. ( the orifice tube included was the r12 one, blue, so I got the recommended one, orange, for r134a.
I think my compressor was going bad, that's why I got it. Can't wait to get it fixed now!
 

jericho

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I'm going to hold off on deciding to use pusher fans and see how this will perform. I don't see much above 90 F but in the future I
will be travelling to hotter climes. But I'm getting ahead of myself, first I gotta get to work!
 

Booyah45828

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I also don't like to just fill the system with refrigerant per spec. I use it as a target but I try to run as little refrigerant as possible to achieve as low a vent temp as possible (I target 36-38deg) since high side pressures can get out of hand easily down here in the high humidity heat. It risks freezing the evap in the spring and fall but that's only about 2 weeks out of the year for us and to be honest it hasn't happened enough for me to notice, and then we don't use a/c for a couple months and after that it's back to hot.

I'm the opposite, I fill to the spec, maybe a little more. We actually do have a spring here in ohio that will be 70 degree temps and extremely humid. We use ac for water removal as much as we do for air cooling. I would for sure have an evaporator freeze up if I undercharged.

Typically, on retrofits, I look for low side pressure to be around 40 idling in the shade, max ac selected. But I also install either a high pressure compressor cut off, and/or a pusher fan, so extreme high side temps don't concern me.

The pusher fan is mainly for idle cooling. On some vehicles I've had issues with it even after messing with orifice tube sizes. I think on some vehicles a viscous fan clutch simply doesn't sense condenser heat. Electric Pusher fans can be had for dirt cheap, and they solve the problem.

To each his own but I've had success with what I do and they last for a long time, at least a few years before needing more refrigerant added again.

This is the biggest thing. You gotta do what works for you, and each truck/climate is different.
 

riphip

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FYI: Moisture in a refrigeration/cooling system is not water/H2O, but hydrochloric acid/HCI.
 
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