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Hi Al, thanks for your help. I decided to throw money at it. I ordered a new parallel flow condenser, new evaporator, & new expansion valve from Original air. In addition, I know my compressor has not been treated right the last 14 years - exposed to air, leaks in the old POA eliminator valve (which I had to replace) Never evacuated, etc... It is a March P411 compressor, so, I will not take a chance, and I will also order a new one.

The suitcase was cleaned out when the engine bay was painted. In addition, I cleaned it out again, and re-sealed it well when I changed the squirrel cage fan motor. The evaporator looked good. I do not plan to mess with the suitcase.

So the plan is - new March P411 compressor, new parallel flow compressor, new expansion valve, new dryer. Let me know if you have any other recommendations. When I get the parts, I will resurrect this thread so you can follow. Thanks.
I'm going to strongly recommend ditching that POA Eliminator and installing your old rebuilt and recalibrated POA valve. If you don't have the old one, find one. I don't think you will be happy with a cycling system. Every time the compressor cycles off you'll experience a rise in temps from the vent. It's better than nothing, but if you're going all in, then go with the system that will give you all in performance.
 

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I'm going to strongly recommend ditching that POA Eliminator and installing your old rebuilt and recalibrated POA valve. If you don't have the old one, find one. I don't think you will be happy with a cycling system. Every time the compressor cycles off you'll experience a rise in temps from the vent. It's better than nothing, but if you're going all in, then go with the system that will give you all in performance.
Beat me to it. I just switched mine from POA eliminator to POA valve. Much better, more consistant temps. I still run a tube and fin condenser, so i get warmer temps when it idles, but im pretty confident with my country road, occcasional stop sign/traffic light test drive, which got to 40, the highway ride will be below 40. I might be charged a little low. If you can throw some more money at it, get a POA valve.

Its odd that your low side didnt get that low, to where it will cycle off. other than i run an A6 type compressor, our setups were the same, but mine would cycle, and i found the temp rise to be really annoying. I had decent vent temps temps, until it cycled off. Thats all better now with the POA.

Dutch kinda mentioned this, but probably the best thing you can do with the POA eliminator is charge it accordingly to where the low side hovers right above the cut off point, so your vent temps stay consistent. Reality is, this would be kinda hard to do with all the variables of ambient temps, airflow, etc.

You are putting all the right parts in your car, the PF condenser is a big key component, but if i could nudge you enough to get a POA valve, i would. and Dutch is right there with me.
 

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Discussion Starter #23 (Edited)
I'm going to strongly recommend ditching that POA Eliminator and installing your old rebuilt and recalibrated POA valve. If you don't have the old one, find one. I don't think you will be happy with a cycling system. Every time the compressor cycles off you'll experience a rise in temps from the vent. It's better than nothing, but if you're going all in, then go with the system that will give you all in performance.
Ok, good suggestion. I do not have one, but, I talked to original air and they can source me a r134a POA valve. I just talked to Mike over there and ordered one. So, I will start the job and resurrect this thread after I receive all the parts - March P412 Compressor, Original Air : P.F. Condenser; New Dryer; New Expansion Valve; new Evaporator, new R134a POA valve to replace the POA eliminator. Thanks again !
 

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Discussion Starter #24
I'm going to strongly recommend ditching that POA Eliminator and installing your old rebuilt and recalibrated POA valve. If you don't have the old one, find one. I don't think you will be happy with a cycling system. Every time the compressor cycles off you'll experience a rise in temps from the vent. It's better than nothing, but if you're going all in, then go with the system that will give you all in performance.
Hi Al, I saw one of posts from Aug. 3rd on oil capacity. If I understand your post correctly, this is what I should be looking at for proper oil in the newly rebuilt system.

New March P414 Compressor (Sanden 7176) - already comes pre-filled with 100 cc of pag oil. I cannot find the exact type of pag oil yet.

So, if I flush all the lines, then I should add an additional amount of pag oil (exact type TBC) for each additional component based your post from Aug. 3rd..

Parallel flow Condenser - 1 oz
Evaporator - 3 oz
Dryer - 1 oz
New r134a POA valve - 0 oz ??
New Expansion valve - 0 oz ??

I plan to just pour this oil into each component, button up the system, then move the clutch on the compressor clockwise twenty turns or so before I vacuum and charge. Do I have this right ? Do I need more oil for the new POA valve or expansion valve ? Thanks !
 

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Here's a thread for you guys from an a/c site I belong to. It shows the thought behind setting up a POA system a/c system on 134a on a 70 Nova which has the same a/c system as the Chevelle. It also shows how to test and calibrate the POA valve on the car. I've attached a video of that process.

It's well written and may offer a few pointers and insight that will help when you do your a/c system restore. https://www.autoacforum.com/viewtopic.php?f=3&t=3096

Below is a pdf file of the same thread. The a/c forum is slow and hard to access at times. It's almost like their server is on dial up. The last pdf covers flushing the system.

When you install your parallel flow condenser, you want to take full advantage of the airflow offered by your cooling system. It should not be mounted tightly against the radiator as this will add heat to the condenser. Seal up any gaps between the radiator and condenser to force the flow through the condenser. The more airflow you have through the condenser, the more efficient your a/c system will be.

Listen for the pop sound when he pressurized the system...pop test, means poa is functioning. Fro there it can be adjusted. When you install the poa and TXV, pour a little refrig oil through them and then allow them to drain. This helps them open and function when you charge the system. If you want to store poa, run the oil through them and store in a ziplock. As long as there is oil coating the insides, it will last for a long storage period. POA's out of systems that have been open for extended periods will deteriorate and need to be rebuilt and calibrated. When switching from r12 to 134a, the valve also needs recalibration as seen in the video.

 

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Hi Al, I saw one of posts from Aug. 3rd on oil capacity. If I understand your post correctly, this is what I should be looking at for proper oil in the newly rebuilt system.

New March P414 Compressor (Sanden 7176) - already comes pre-filled with 100 cc of pag oil. I cannot find the exact type of pag oil yet.

So, if I flush all the lines, then I should add an additional amount of pag oil (exact type TBC) for each additional component based your post from Aug. 3rd..

Parallel flow Condenser - 1 oz
Evaporator - 3 oz
Dryer - 1 oz
New r134a POA valve - 0 oz ??
New Expansion valve - 0 oz ??

I plan to just pour this oil into each component, button up the system, then move the clutch on the compressor clockwise twenty turns or so before I vacuum and charge. Do I have this right ? Do I need more oil for the new POA valve or expansion valve ? Thanks !
That is correct. Those numbers come from the Chassis Service Manual for 1970. I run a small amount of oil through the TXV and POA just to get them lubed up so they'll function when we start up the system. I'll let the excess fluid drain from these before install. In theory, this is not necessary because the oil will push through the system while you charge. But some old a/c guru taught me this, so I go with his experience. There should be no measurable quantity of oil left in these pieces.
 

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With the numbers listed it’s looking like you have a valve out inside the compressor.
Normal high side and high low side. Or a faulty metering device.( overloading the evaporator with refrigerant)
Line temperatures would really help in diagnosing the problem.
 

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Discussion Starter #29
With the numbers listed it’s looking like you have a valve out inside the compressor.
Normal high side and high low side. Or a faulty metering device.( overloading the evaporator with refrigerant)
Line temperatures would really help in diagnosing the problem.
The line temperatures were never that great. Cold line was cold, hot line was hot, but, not like my other cars. The old Sanden compressor really squeals the belt when you first turn it on, and I have the belt tight, so, I do not trust it anymore. Compressor off, equalized pressure was 91 PSI. The low side gets there pretty fast after tuning off the motor.

The new chrome compressor - MCH-P412 is already here. The new PF condenser, dryer, expansion valve are already shipped. I am waiting on the Evaporator and r134 POA valve to be shipped. The compressor uses Sanden SP-15 PAG oil, so, that is what I will be using in the system. I am changing every major part of the system, so, I expect the pressures to change drastically for the better. Stay tuned. Thanks.
 

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Discussion Starter #30 (Edited)
Hi Al, I saw one of posts from Aug. 3rd on oil capacity. If I understand your post correctly, this is what I should be looking at for proper oil in the newly rebuilt system.

New March P412 Compressor (Sanden 7176) - already comes pre-filled with 100 cc of pag oil. I cannot find the exact type of pag oil yet.

So, if I flush all the lines, then I should add an additional amount of pag oil (exact type TBC) for each additional component based your post from Aug. 3rd..

Parallel flow Condenser - 1 oz
Evaporator - 3 oz
Dryer - 1 oz
New r134a POA valve - 0 oz ??
New Expansion valve - 0 oz ??

I plan to just pour this oil into each component, button up the system, then move the clutch on the compressor clockwise twenty turns or so before I vacuum and charge. Do I have this right ? Do I need more oil for the new POA valve or expansion valve ? Thanks !
ok, so, I talked to Mike over at Original Air (Tampa, FL), the numbers we are looking at for oil are too much for my aftermarket March P412, (Sanden) compressor. What Mike told me is that for a complete system with a similar Sanden compressor they put in a max of 210 cc oil. He said I could put that in, but, no more.

The numbers we are looking at above are used when replacing just one part in the system, ie. if you replace the condenser, then, it is taking 1 oz. of compressor pump oil with it. If you replace the Evaporator, then, it is taking 3 oz. of compressor pump oil with it. The concept is that you have to replace that oil in those components to keep the right amount of oil in the system.

My understanding now is that if you start with a new system, with all new components, then, all you need is a full compressor of oil and no more oil in the other components. As the system gets used, the compressor oil gets distributed in the various components, so, if you replace one, you have to estimate the amount of oil you lose, so, it can be replaced. That is what the chart is showing you in the Chevelle manual.

So, for example, if you system needs 11 oz., that is 11 oz just for the compressor. You put 11 oz into the compressor, button up the system, vacuum and charge. Your compressor is not specified as only needing 6 oz and the other parts needing 5 oz. In fact, the documentation is telling us that this oil that the compressor needs is then distributed during usage and must be replaced when a new part is introduced.

The March MCH-P412 says it comes with 100 cc of Sanden SP-15 Pag oil. So, now I have to decide if I add another 100 cc of SP-15 to the whole system or not add any at all except the 100 cc that is already in the compressor.

Do I have this right ?
 

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Discussion Starter #31 (Edited)
The parallel flow condenser, dryer, & expansion valve arrived from Original air (Tampa, Fl). It looks like it will work perfect with all my old lines, and the mounting brackets look perfect. :smile2: I like how the dryer and condenser are painted black. I am still waiting on the evaporator and r134a POA valve. Here are some pics of the condenser:







 

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ok, so, I talked to Mike over at Original Air (Tampa, FL), the numbers we are looking at for oil are too much for my aftermarket March P412, (Sanden) compressor. What Mike told me is that for a complete system with a similar Sanden compressor they put in a max of 210 cc oil. He said I could put that in, but, no more.

The numbers we are looking at above are used when replacing just one part in the system, ie. if you replace the condenser, then, it is taking 1 oz. of compressor pump oil with it. If you replace the Evaporator, then, it is taking 3 oz. of compressor pump oil with it. The concept is that you have to replace that oil in those components to keep the right amount of oil in the system.

My understanding now is that if you start with a new system, with all new components, then, all you need is a full compressor of oil and no more oil in the other components. As the system gets used, the compressor oil gets distributed in the various components, so, if you replace one, you have to estimate the amount of oil you lose, so, it can be replaced. That is what the chart is showing you in the Chevelle manual.

So, for example, if you system needs 11 oz., that is 11 oz just for the compressor. You put 11 oz into the compressor, button up the system, vacuum and charge. Your compressor is not specified as only needing 6 oz and the other parts needing 5 oz. In fact, the documentation is telling us that this oil that the compressor needs is then distributed during usage and must be replaced when a new part is introduced.

The March MCH-P412 says it comes with 100 cc of Sanden SP-15 Pag oil. So, now I have to decide if I add another 100 cc of SP-15 to the whole system or not add any at all except the 100 cc that is already in the compressor.

Do I have this right ?
Your Denso compressor should maintain a minimum 30-50 percent of the initial compressor fill amount within the compressor after being charged and run. That's to say if the compressor is removed from the system and drained it would have about half of the 3.38 oz oil charge = 1.64 oz.

The Chevelle A/C Components will then retain a total of 5 oz and add the 50% retained value of 1.64oz = about 6.5 oz = 1.92 cc. So the 200 cc or 6.76 oz recommended would be your target.

https://www.denso-am.eu/media/651804/160461-denso-leaflet-practical-tips-a4_en_.pdf

If you try to run your system with only the initial compressor oil charge of 3.38 oz on the Chevelle system, you'll soon be replacing that compressor as the components will easily hold and starve your compressor of oil.
 

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To much oil in the system is as bad as to little. Oil doesn’t stay in one spot it moves with the refrigerant. If the compressor calls for 11 ounces of oil that’s how much you put into a new system. At any given time that oil will be moving throughout the system.
If you replace a component. You will need to add some oil back in. Best way would be to measure the oil in the removed part. If you guess you could have to much or to little.
 

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Discussion Starter #34 (Edited)
Your Denso compressor should maintain a minimum 30-50 percent of the initial compressor fill amount within the compressor after being charged and run. That's to say if the compressor is removed from the system and drained it would have about half of the 3.38 oz oil charge = 1.64 oz.

The Chevelle A/C Components will then retain a total of 5 oz and add the 50% retained value of 1.64oz = about 6.5 oz = 1.92 cc. So the 200 cc or 6.76 oz recommended would be your target.

https://www.denso-am.eu/media/651804/160461-denso-leaflet-practical-tips-a4_en_.pdf

If you try to run your system with only the initial compressor oil charge of 3.38 oz on the Chevelle system, you'll soon be replacing that compressor as the components will easily hold and starve your compressor of oil.
Good point. The 210cc of oil that Original air told me about was for the Sanden 500 series which holds more oil than the sanden 7176 types. This is what Original air uses in their systems. I found this recommendation regarding Sanden 7176 compressor types which comes with 100 cc of oil in the compressor.

6.8 Oil Charge

• Oil Circulation Ratio (OCR) should be between 3.3% and 8% ratio of oil to refrigerant
by weight.

6.8.1 Oil Flow Theory

• Compressor lubrication occurs as the oil which circulates with the refrigerant passes
through the compressor crankcase during operation. The Sanden SD series
compressor achieves optimal durability and cooling performance when oil circulates
through the system at a ratio of 3.3% to 8% oil to refrigerant. Excess oil can act as an
insulator limiting heat transfer in the evaporator and condenser, while too little oil can
negatively affect durability.
• Oil will collect in low pressure cool components (evaporator, accumulator and suction
hose) of the refrigerant loop. For example a long suction hose which sags can collect
several ounces thus reducing overall oil circulation ratio.

6.8.2 Oil Charging

6.8.2.1 Passenger Car, Light Duty Truck Single Evaporator
Refrigerant charges 24oz (680g) to 40oz (1133g)

• 135cc oil TXV systems
• 240 cc oil in orifice tube systems

Less than 56oz or 1600g of refrigerant charge

1. The desired oil charge for the systems with unusually long hoses, such as trucks, tractors,
etc., can be determined based on the total refrigerant charge when less than 56 oz. (1600g)
refrigerant is used.

2. Calculate the desired oil charge as below:

Oil amount (oz.) = [(Refrigerant charge in oz. x 0.06) + 2.2] ÷ 0.9.
Oil amount (cc) = [(Refrigerant charge in grams x 0.06) + 66] ÷ 0.9.

Note: For systems with very long hose runs add an additional 1.0 oz (30cc) of oil for
each 10 foot of hose plus an additional 1.1 oz (33cc) as a safety measure.
 

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Discussion Starter #35
Less than 56oz or 1600g of refrigerant charge

1. The desired oil charge for the systems with unusually long hoses, such as trucks, tractors,
etc., can be determined based on the total refrigerant charge when less than 56 oz. (1600g)
refrigerant is used.

2. Calculate the desired oil charge as below:

Oil amount (oz.) = [(Refrigerant charge in oz. x 0.06) + 2.2] ÷ 0.9.
Oil amount (cc) = [(Refrigerant charge in grams x 0.06) + 66] ÷ 0.9.
So, if I make the calculation based on 48 oz of r134a, I get 5.64 oz or 166 cc of SP-15 pag oil for the whole system -- based on the Sanden peanut compressor - 7176 - March MCH-P412
 

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Discussion Starter #36
All the parts from Original Air (Tampa) arrived. I started the Parallel flow Condenser job last night after work. I am embarrassed to tell you how long it took me to do the swamp. I could do it in less than half the time now... lol. Some recommendations that I followed from this forum -- only remove the front bolts from the bumper, use a jack to lower and raise the bumper, air rachet makes things go much faster, there is a lot of screw turning. The new parallel flow condenser fit perfect. My old lines fit perfect, only some slight bending. I will install the new compressor, new expansion valve and new POA valve today. I will probably install the evaporator on thursday, then hook up the vacuum and charge. Here are some pics from last night.

Disassembly of front end to put in new Parallel Flow Condenser:
















Here are installation pics of the new Parallel Flow Condenser and Dryer:







More to come the next few days as I do the compressor, evaporator, expansion valve.
 
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Discussion Starter #37
Ok, I replaced the Evaporator, POA, and Expansion Valve tonight. As explained in the forum, I was able to just remove half of the suitcase to remove the Evaporator. I had to take my tall valve cover off to get enough clearance. I used black weather seal gum to seal up the suit case. Note: I had already removed the other half of the suitcase a few years ago to upgrade my fan motor, but, I did not notice all the trash in the other half. Some of my old Evaporator was clogged with dirt and leaves, and there were a lot of leaves in the suitcase. I also jacked up the front of the Chevelle and took the front passenger tire off. I got to some of the bolts from underneath or through the wheel well opening. Here are some pics of the install:

Original POA eliminator and old Evaporator







Some cob webs and leaves in the Evaporator and in the suitcase. I cleaned it out good.





New Evaporator, New R134a POA, and New Expansion Valve Installed:











Tomorrow, I change the Compressor, finish buttoning it up (all the lines have been cleaned and taped), vacuum, and Charge. I will report my results.
 

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Nice work Harry. It always cracks me up when someone says their 50 year old evaporator has never been cleaned but they are sure it's clean. I mean how dirty could it be? They are usually much dirtier than yours was.

Say good riddance to that POA eliminator. Hello cool consistent airflow.:grin2: It's not cheap to be cool and being cool aint cheap.;)
 

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Discussion Starter #39
Nice work Harry. It always cracks me up when someone says their 50 year old evaporator has never been cleaned but they are sure it's clean. I mean how dirty could it be? They are usually much dirtier than yours was.

Say good riddance to that POA eliminator. Hello cool consistent airflow.:grin2: It's not cheap to be cool and being cool aint cheap.;)
Thanks. I was expecting my suitcase to be clean. I was shocked how dirty it was, especially since I replaced the blower motor on the other side a few years back and blew some air from my compressor into the other side of the suitcase. It cleaned nothing.... I was fighting an air cond. air flow speed issue back then, and went through all my ducts and bought a new fan motor---- I should have cleaned the other side of the suitcase...lol.
 
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Now you know why I ask folks, " Can you guess how many Cu. Ft. of " OUTSIDE DIRTY AIR " has gone through the evaporator in the last 40 / 50 years? Many folks have told my " My evaporator is nice and KLEEN ?"... DAA!
Now your air/flow will be up to specs. A lot of people do not believe me when I tell them " Being KOOL Aint CHEEEEEP".
Also the little rubber pieces ( condenser) with threads on both ends , I bought a dozen or so a while back from Granger. They were around a buck or two each. I have some spares if you need some.
Do you agree with this..... Removing a stock 1970 Chevelle A/C condenser is , Just " So much fun "...................LOL:laugh:
Can you say " Labor Intensive ".
Bob
 
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