AC Compressor replacement

I am finally ready to install a rebuilt AC compressor along with a new expansion tube and Accumulator in my 93 Lumina APV mini van. The factory manual has lots
of confusing info about adding oil as does the instruction that came with the rebuild. They both say to drain and measure the oil in the old compressor and use this amount to calculate the amount to add to the replacement.
Problem is, to get the old comp out I had to turn it every which way and all of the oil just spilled out on my driveway so I did not get a chance to measure it.
So my question #1 is: Is it better to err on the side of too much or too little?
#2: The factory manual shows two compressor models, one has an oil drain bolt. My model does not so I can only assume the oil goes in and drains out the Inlet and/or Outlet ports, right? Does it matter whether inlet or outlet?
Thanks in advance for any answers advice or suggestions.
Bob
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Has the system been converted to 134a yet? If not do you have access to r12? I have never used the old oil method. You will seldom get more than a little out of the old one. It looks like alot when it is spilled on concrete. If your compressor ships dry(with no oil, I would add 5 ounces. Measure it out with a measuring cup. Too much oil will cause it to blow warmer, not enough will ruin the compressor. Just make sure you us the right type of oil(134a or r12) After pouring the oil in the compressor, install the cap from the new compressor on the openings to keep the oil in during instalation. If you have a stud to hold the line on which you have to transfer from the old compressor to the new one, the cap won't fit with the stud installed. Just cut the cap in half making 2 plugs and they will install next to the stud. 5 ounces will be enough since you are changing the accumulator. Usually 4-6 ounces is perfect. 3 will work but not as long as 4 will. If you have had it converted to 134a realize that you can't install the same amount of 134a as the original sticker says. If it is converted, there may be an added on sticker showing the amount of 134a.

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Thanks for the reply. It is an original 134a sytem. The replacement compressor shipped dry. There is no stud, the cap is held on with a hex head bolt. I had planned on putting te cap back on. You have to get the compressor in past the frame from the bottom without the bracket in place, hold the compressor out of the way and then install the bracket, then bolt the compressor to the bracket. That is the only way it would come out.
The manual says to add some oil to the accumulator also. Would you still add the 5 to the compressor?
Thanks again for your advice.

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The system has a specified oil capacity, just like the engine... The capacities for the individual components take into account the fact that oil is constantly in circulation when the system is running but then settles out into the individual components when it is shut down and circulation stops. Adding up the capacities for the individual components should equal the total of the system capacity.
Normal prudent course of action when replacing a grenaded compressor is to flush all components, blow them dry and then add the specified amount of oil to each component, evacuate, recharge and enjoy the cool.
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Thanks for the reply.
I am probably being imprudent to even bother with this 12 year old, 196,000 mile minivan. Anyway, the compressor did not grenade, it seems the pulley just seized. Can you flush the the components in place and if so how? I have no intention of pulling the condensor and evaporator, it has taken me three weeks to remove the compressor, acumulator and expansion valve!.

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It was probably the compressor seizing up. Anyway the orifice tube(the tube with the screen) was probably loaded with a greyish junk by that many miles. If the compressor was just worn out and seized, there will always be a certain amount of particulate mattr in the system. Some shops shop would flush it out by usuing a solvent under pressure never removing the parts. But if the orifice tube was full of lots of stringy pieces, it probably has metal in the system. If it only has what looks like graphite, I wouldn't worry about it. With that many miles, I would install the parts and go with it. The orifice tube acts as a restriction in the system but also acts like a filter. The worst that would happen is that the new tube would clog up causing you to remove it and clean it and evacuate and recharge again. You are not looking to go another 196,000. That doesn't mean not to do a perfect job, but too many people get caught up in spending too much money on something old. what does the orifice tube look like?

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Thhanks for your reply, The orifice tube looks normal except for graphite looking coating on it. The rotor or whatever it is inside the compressor turns freely if you turn what I think is the clutch but the pulley is locked solid..
The original symptom that prompted this replacement was not non working AC but the engine would not start. After replacing the starter and battery I finally turned to this NG and quickly was tipped that it could be a siezed AC pulley, which it was. Prior to the seizure the AC worked, although not great.
I am going to try to put everthing back togeteger this week. Right now having issue with the AC bracket bracket mounting holes not lining up. I don't realy need this van anymore but it has become a ersonal challenge.

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I don't know... if it still runs good and you can do the AC work yourself, it makes sense. Sometimes it better the devil you do know than the one you don't.

Sure, just disconnect the components, rig up some hose and a funnel and pour in a half gallon of denatured alcohol, then blow it out with compressed air. Repeat until clean.
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Thanks for the tip.
wrote:

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