r134a numbers with stock Condenser & replacement POA - Page 2 - Chevelle Tech
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post #16 of 78 (permalink) Old Aug 14th, 19, 5:23 PM Thread Starter
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Harry
 
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Re: r134a numbers with stock Condenser & replacement POA

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I am going for a spin now in the summer heat and see how low the center vent temp goes. To be cont.....
I just went for a 10 min. ride in the sun with 102 deg. heat with the fan on high. The best I could get in the city was 58 deg. out the center vent. This was cruising in 4th gear at 2K rpm. At idle which was 850 rpm, it would creep up to 65 deg. in 3 min. On the fwy, I believe it will cool down 2 to 3 deg. more, so, mid 50's would be best in 102 deg. heat. It's not horrible, but, I am not satisfied. I will take the next steps to improve....
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Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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post #17 of 78 (permalink) Old Aug 14th, 19, 5:28 PM
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Re: r134a numbers with stock Condenser & replacement POA

We're not going to get an accurate pressure reading with the car in the garage. We need a steady ambient airflow through the cond to get the info we need. Also, starting the system from a heat-soaked state won't help us either. The engine needs to be running and temps and pressures stabilized to get numbers we can rely on.

Do you need to go into the suitcase to do any cleaning or work? Sort of bummed if the answer is yes, because I would like to pull the evap and flush it along with the rest of the system if you decide to install new parts. Starting from scratch will allow accurate oil levels in the system. Compressor, drier and txv valves are never flushed.

Your compressor is outputting necessary pressures. I would pull it if you install new parts, drain and measure the oil in a pan with a paper towel in the bottom. Check for metal debris. Spin the input shaft to remove all the oil, then refill. If you are not seeing metal flake in the oil, not hearing strange noises or seeing oily buildup around the input shaft your compressor is probably fine.

Lack of cooling can be caused by moisture in the system. Replacing the drier is a must when opening the system. If the system was open for any length of time, it's probably got a lot of moisture and contaminants in the system. Don't uncap your drier until you are ready to evacuate the system.

The sight glass looks ok, 134a is a greenish cloudy color. You can tell if the oil is streaking on the glass, I don't see it in yours but I'm not seeing the realtime flow. The sight glass on 134 will usually still show some bubbles on a properly charged system. You'll almost always see a rush of bubbles when the compressor kicks in.

TXVvalve, yeah I would replace that if the system gets opened to change out the cond.

If you want to peak the current system, we'll need some accurate numbers with the system stabilized, engine at 1500rpm and a good consistent flow of air through the cond with an accurate ambient temp reading.
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post #18 of 78 (permalink) Old Aug 14th, 19, 5:58 PM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

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Originally Posted by DUTCH MAX HEADWORK View Post
We're not going to get an accurate pressure reading with the car in the garage. We need a steady ambient airflow through the cond to get the info we need. Also, starting the system from a heat-soaked state won't help us either. The engine needs to be running and temps and pressures stabilized to get numbers we can rely on.

Do you need to go into the suitcase to do any cleaning or work? Sort of bummed if the answer is yes, because I would like to pull the evap and flush it along with the rest of the system if you decide to install new parts. Starting from scratch will allow accurate oil levels in the system. Compressor, drier and txv valves are never flushed.

Your compressor is outputting necessary pressures. I would pull it if you install new parts, drain and measure the oil in a pan with a paper towel in the bottom. Check for metal debris. Spin the input shaft to remove all the oil, then refill. If you are not seeing metal flake in the oil, not hearing strange noises or seeing oily buildup around the input shaft your compressor is probably fine.

Lack of cooling can be caused by moisture in the system. Replacing the drier is a must when opening the system. If the system was open for any length of time, it's probably got a lot of moisture and contaminants in the system. Don't uncap your drier until you are ready to evacuate the system.

The sight glass looks ok, 134a is a greenish cloudy color. You can tell if the oil is streaking on the glass, I don't see it in yours but I'm not seeing the realtime flow. The sight glass on 134 will usually still show some bubbles on a properly charged system. You'll almost always see a rush of bubbles when the compressor kicks in.

TXVvalve, yeah I would replace that if the system gets opened to change out the cond.

If you want to peak the current system, we'll need some accurate numbers with the system stabilized, engine at 1500rpm and a good consistent flow of air through the cond with an accurate ambient temp reading.
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.
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Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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post #19 of 78 (permalink) Old Aug 14th, 19, 6:03 PM
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Re: r134a numbers with stock Condenser & replacement POA

New receiver/drier. And a bottle of oil specific to requirements for the compressor.

Flush and dry any components not replaced including hoses. Cap the or tape up if you plan to leave any part open. The oil is a dust magnet.
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post #20 of 78 (permalink) Old Aug 15th, 19, 12:10 AM
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Re: r134a numbers with stock Condenser & replacement POA

Use a fan in front of the condenser when you have the system completely assembled and operating, it'll be like driving it down the road and good luck!!
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post #21 of 78 (permalink) Old Aug 15th, 19, 12:28 AM
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by hjdca View Post
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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post #22 of 78 (permalink) Old Aug 15th, 19, 7:54 AM
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
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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post #23 of 78 (permalink) Old Aug 15th, 19, 10:34 AM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
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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Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers

Last edited by hjdca; Aug 15th, 19 at 10:51 AM.
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post #24 of 78 (permalink) Old Aug 15th, 19, 6:10 PM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
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 !

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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post #25 of 78 (permalink) Old Aug 15th, 19, 6:36 PM
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Re: r134a numbers with stock Condenser & replacement POA

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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post #26 of 78 (permalink) Old Aug 15th, 19, 6:49 PM
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by hjdca View Post
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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post #27 of 78 (permalink) Old Aug 17th, 19, 11:19 PM
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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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post #28 of 78 (permalink) Old Aug 17th, 19, 11:24 PM
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When you shut the ac off how fast does the suction line get hot?
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post #29 of 78 (permalink) Old Aug 18th, 19, 12:28 AM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by Jasons 69 Chevelle View Post
With the numbers listed itís 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.

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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post #30 of 78 (permalink) Old Aug 21st, 19, 3:56 PM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by hjdca View Post
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 ?

Harry
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers

Last edited by hjdca; Aug 21st, 19 at 4:18 PM.
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