r134a numbers with stock Condenser & replacement POA - Chevelle Tech
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post #1 of 29 (permalink) Old Aug 13th, 19, 5:49 PM Thread Starter
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Harry
 
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r134a numbers with stock Condenser & replacement POA

Hi Guys, I have my Chevelle converted to R134a with the replacement POA, Sanden Compressor, stock Condenser, & new Dryer. In 100 deg. temperatures, the best I can get on the fwy is 55 deg. out of the center vent. At idle, 925 rpm, it reads up to 65 deg. out of the center vent in 100 deg. heat.

When starting the cold Chevelle in 90 degree weather in the shade at 1400 rpm, here are my r134a readings with no fan upfront. I am running the stock clutch fan. What do you think about these numbers ?

At cold startup to around 10 min. to warm up.

Low side High side
44 155
43 155
42 170
44 175
48 185
50 195
52 200
53 210

Of course, the air in the car is much colder at first startup and the air gets warmer as the Chevelle warms up.

I am thinking I need a new parallel flow condenser from original air to get lower temperatures. What do you think ? Thanks for any advice.

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 #2 of 29 (permalink) Old Aug 13th, 19, 7:39 PM
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Re: r134a numbers with stock Condenser & replacement POA

I have been playing with 69--72 Chevelles A/C units for many years. Just so you know. I get 38-40 degrees out of my center vent, Using a Temp. gauge from Advance.
If you are going to convert to R-134, Its a pay me now or pay me later.
A stock org. condenser will WORK very well "" IF "" you can maintain a speed of 35-40 M.P.H..... WHY? The stock cond. has tubes about 3/8" in dia., SO what. R-134 runs a lot hotter than R-12. ( It has a VERY different expansion rate, It runs about 20% HOTTER ) So, I would advise using a P.Flow cond.
The stock Org. A/C hoses.... R-134 will bleed through the stock hoses WHY?
R-134 has smaller molecules than R-12. I use R12/R-134 compatible hoses.
The Factory installed evaporator, Well chances are it is plugged up a bit, Wadda ya mean? Can you guess how many Cubic feet of air has gone through this unit in " 50 " years. ( I replaced my evaporator a while back.) WHY?
It was plugged shut around the edges and It was tough to see through. The new condenser, WOW, I could watch-T.V. through it!
The R-134 Charge. If you are working with a STOCK-C-60 unit converted to R-134. Use the 80% rule. 80% of 60 ozs. = 48ozs.
Charge your Factory converted C-60 unit with "" 48 ozs. "" of R-134 and DONT EVEN LOOK AT THE GAUGES. I drove my 70 to the Ohio show last week, The wife said turn on the A/C, FAN is on 4--- She says toooo kold turn it down, Now fan on 3--- She says toooo KOLd.... Fan is now on " 2 " it got a little chilly so I opened a wing window. Yes my factory (converted to R-134 operating well)
Also.......... If you can find a load of R-12 go that route, NOTHING is better than a factory unit with " R-12 " being pump through the system.
Yes, I said nothing is better than " R-12 ".
Be KOOL
Bob
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post #3 of 29 (permalink) Old Aug 13th, 19, 9:53 PM
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Re: r134a numbers with stock Condenser & replacement POA

What's a replacement POA? A POA eliminator kit or a rebuilt POA? Do you know where the rebuilt POA valve pressure is set?

Do you have a positive shutoff for coolant to the heater core? I prefer a ball valve over the stock vac operated valve. If you can feel heat after the valve, it's flowing heat into the suitcase. The more heat you can keep out of the suitcase the better.

At 90 degrees ambient, you are looking for 250-270 psi on the high side. I'd probably shoot for 260. If you can charge to that and maintain your low side below 55psi, you should get some lower temps at the evap. Place a box fan in front of the radiator while charging and hold 1500rpm. A HD or severe duty fan clutch will move more air, it may help. I hope you are running a fan shroud. I know for a fact that a parallel flow condenser will get you better and more consistant cooling. But think you can still get more out of what you are currently running.

Your low side pressure is swinging high, so watch them as you charge. Make sure your TVX bulb is tight against the evap tube and well insulated with tar insulation tape.

If you have a temp gun, get a temp for the inlet line and outlet line from the condenser and evap. For the evap, measure temp from the the outlet of the TXV valve and outlet of the evap. Get the center vent temp and ambient temp too. Any time the ambient temp changes, I'll need to see gauge readings high and low.

I'm seeing some things I'm not liking. Your low side is running a little high. If you charge and it holds or drops and vent temps drop you should be ok. If it starts coming up, your POA or TXV valve may be releasing too much pressure. Is your POA valve frosting up?
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post #4 of 29 (permalink) Old Aug 13th, 19, 10:12 PM
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by Robinls5 View Post
I have been playing with 69--72 Chevelles A/C units for many years. Just so you know. I get 38-40 degrees out of my center vent, Using a Temp. gauge from Advance.
If you are going to convert to R-134, Its a pay me now or pay me later.
A stock org. condenser will WORK very well "" IF "" you can maintain a speed of 35-40 M.P.H..... WHY? The stock cond. has tubes about 3/8" in dia., SO what. R-134 runs a lot hotter than R-12. ( It has a VERY different expansion rate, It runs about 20% HOTTER ) So, I would advise using a P.Flow cond.
The stock Org. A/C hoses.... R-134 will bleed through the stock hoses WHY?
R-134 has smaller molecules than R-12. I use R12/R-134 compatible hoses.
The Factory installed evaporator, Well chances are it is plugged up a bit, Wadda ya mean? Can you guess how many Cubic feet of air has gone through this unit in " 50 " years. ( I replaced my evaporator a while back.) WHY?
It was plugged shut around the edges and It was tough to see through. The new condenser, WOW, I could watch-T.V. through it!
The R-134 Charge. If you are working with a STOCK-C-60 unit converted to R-134. Use the 80% rule. 80% of 60 ozs. = 48ozs.
Charge your Factory converted C-60 unit with "" 48 ozs. "" of R-134 and DONT EVEN LOOK AT THE GAUGES. I drove my 70 to the Ohio show last week, The wife said turn on the A/C, FAN is on 4--- She says toooo kold turn it down, Now fan on 3--- She says toooo KOLd.... Fan is now on " 2 " it got a little chilly so I opened a wing window. Yes my factory (converted to R-134 operating well)
Also.......... If you can find a load of R-12 go that route, NOTHING is better than a factory unit with " R-12 " being pump through the system.
Yes, I said nothing is better than " R-12 ".
Be KOOL
Bob
Can you reference what pressures you are running with your r134a POA controlled system at a specified ambient temp?

I normally see lower lowside pressures than what HARRY is currently showing for a POA SYSTEM ON R134A.
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post #5 of 29 (permalink) Old Aug 13th, 19, 11:30 PM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
What's a replacement POA? A POA eliminator kit or a rebuilt POA? Do you know where the rebuilt POA valve pressure is set?

Do you have a positive shutoff for coolant to the heater core? I prefer a ball valve over the stock vac operated valve. If you can feel heat after the valve, it's flowing heat into the suitcase. The more heat you can keep out of the suitcase the better.

At 90 degrees ambient, you are looking for 250-270 psi on the high side. I'd probably shoot for 260. If you can charge to that and maintain your low side below 55psi, you should get some lower temps at the evap. Place a box fan in front of the radiator while charging and hold 1500rpm. A HD or severe duty fan clutch will move more air, it may help. I hope you are running a fan shroud. I know for a fact that a parallel flow condenser will get you better and more consistant cooling. But think you can still get more out of what you are currently running.

Your low side pressure is swinging high, so watch them as you charge. Make sure your TVX bulb is tight against the evap tube and well insulated with tar insulation tape.

If you have a temp gun, get a temp for the inlet line and outlet line from the condenser and evap. For the evap, measure temp from the the outlet of the TXV valve and outlet of the evap. Get the center vent temp and ambient temp too. Any time the ambient temp changes, I'll need to see gauge readings high and low.

I'm seeing some things I'm not liking. Your low side is running a little high. If you charge and it holds or drops and vent temps drop you should be ok. If it starts coming up, your POA or TXV valve may be releasing too much pressure. Is your POA valve frosting up?
Thanks for your reply ! It is a POA eliminator kit with the Sanden compressor, so maybe I should check the TXV ? How should the TXV bulb be attached to the evap tube ? Should I use a hose clamp or just clamp it with the tar insulation tape. The compressor is running full time. I get no frosting. The low side tube is cold and the high side tube is hot. The Cold side tube gets slightly warmer as the Chevelle gets hotter at 1400 rpm. I am running the stock 7 blade fan with shroud and heavy duty clutch fan and Griffin radiator. The motor stays cool at idle with the air conditioning on.

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 #6 of 29 (permalink) Old Aug 14th, 19, 12:00 AM
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Re: r134a numbers with stock Condenser & replacement POA

The OEM --TXV was held in place with Factory clamps. I use two small nylon ties and pull it down tight and use the tar tape. I have not used a POA eliminator, and never will.
You can get a C-60 to blow some cold air using all the stock parts. Adjust your P.O.A. for R-134 /// P. Flow condenser /// I am using a 10 Cyl. ( R-134) compressor from the Fla. guys ( painted black) Stock replacement for the A-6.
A new Evap. core aint a bad idea. Being KOOL is not cheeeeeep!
Over charging a C-60 system is real easy. I have done it. If you ever change the Evaporator. Pull the engine side of the suitcase OFF. It will fall out.
No need to mess with the inner fender and the blower side of the suitcase.
Bob
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post #7 of 29 (permalink) Old Aug 14th, 19, 12:15 AM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
What's a replacement POA? A POA eliminator kit or a rebuilt POA? Do you know where the rebuilt POA valve pressure is set?

Do you have a positive shutoff for coolant to the heater core? I prefer a ball valve over the stock vac operated valve. If you can feel heat after the valve, it's flowing heat into the suitcase. The more heat you can keep out of the suitcase the better.

At 90 degrees ambient, you are looking for 250-270 psi on the high side. I'd probably shoot for 260. If you can charge to that and maintain your low side below 55psi, you should get some lower temps at the evap. Place a box fan in front of the radiator while charging and hold 1500rpm. A HD or severe duty fan clutch will move more air, it may help. I hope you are running a fan shroud. I know for a fact that a parallel flow condenser will get you better and more consistant cooling. But think you can still get more out of what you are currently running.

Your low side pressure is swinging high, so watch them as you charge. Make sure your TVX bulb is tight against the evap tube and well insulated with tar insulation tape.

If you have a temp gun, get a temp for the inlet line and outlet line from the condenser and evap. For the evap, measure temp from the the outlet of the TXV valve and outlet of the evap. Get the center vent temp and ambient temp too. Any time the ambient temp changes, I'll need to see gauge readings high and low.

I'm seeing some things I'm not liking. Your low side is running a little high. If you charge and it holds or drops and vent temps drop you should be ok. If it starts coming up, your POA or TXV valve may be releasing too much pressure. Is your POA valve frosting up?
Thanks Al. You were right. My TVX bulb was not tight against the evap tube and there was adhesive all over both. I cleaned the bulb (3M adhesive remover works) and the tube and attached it with a zip tie on top of the tube instead of the bottom. Then, I reapplied the tar. Here are some pics. I am going to retest now and will post results. 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
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post #8 of 29 (permalink) Old Aug 14th, 19, 12:21 AM
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Re: r134a numbers with stock Condenser & replacement POA

Mount your bulb at the 4 or 8 o'clock position. You can hold it there with a hose clamp or zipties if you like, just don't get too crazy tight and bend the tubes. Usually, the tar/foil tape will hold it without any mechanical means of connection.

Without your high pressure at the required pressure on the chart, it's difficult for me to tell what will happen as you charge the system to the correct high pressure for ambient temp. If the low side goes up in pressure as you charge, you can stop. With that system, your low pressure should read 21-28 psi on the low side. As the low side pressure switch determines when the compressor will cycle off. It does this to maintain the evap at a temp above freezing, which about 27 psi, but it's set lower to counter airflow over the evap.

You have a choice, charge to specified high pressure, and see what happens to the low side pressures, I can't determine what will happen, I need a fully charged system on the high side and right now you are undercharged OR

Change out the TVX valve and you may as well upgrade to a parallel flow condenser since you have to recover the refrigerant. You should also change the drier anytime you open the system. Not sure you will be happy with a system that retains the stock condenser. Your temp swings will be greater with the stock condenser and lackluster at idle or in traffic.

When you started, was this a closed system that was still retaining pressure? Then you swapped in the compressor and poa eliminator and replaced the drier? You did evacuate the system? Did you add any oil? Are you using a refrigerant that is free of oil and sealants? I need to know where you stand...as in what you did, the condition before you started and your procedure to this point. This will help insure that all bases are covered.

Your system should incorporate a high pressure shut off switch to protect the compressor from high side pressures.
Attached Files
File Type: pdf POA Eliminator Kit 15-402 15-403.pdf (1.06 MB, 9 views)
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post #9 of 29 (permalink) Old Aug 14th, 19, 12:27 AM
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by hjdca View Post
Thanks Al. You were right. My TVX bulb was not tight against the evap tube and there was adhesive all over both. I cleaned the bulb (3M adhesive remover works) and the tube and attached it with a zip tie on top of the tube instead of the bottom. Then, I reapplied the tar. Here are some pics. I am going to retest now and will post results. Thanks again.






That could do it. Fingers crossed here!

Feel the backside of the heater shut off tube. Those sometimes leak, any added heat to the suitcase will degrade you temp potential through the evap. This becomes more important if the seals are old or the actuator doors are not sealing completely.
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post #10 of 29 (permalink) Old Aug 14th, 19, 1:07 AM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
That could do it. Fingers crossed here!

Feel the backside of the heater shut off tube. Those sometimes leak, any added heat to the suitcase will degrade you temp potential through the evap. This becomes more important if the seals are old or the actuator doors are not sealing completely.
Ok Al, I took it out for a spin rather than hook up the gauges again. It is evening - 80 degrees out. The best I got on city streets - not more than 2K rpm in 4th gear (3:73 gears) was 46 deg. out the center vent on high fan. On one notch before high, I could manage 43 deg.. At idle, 850 to 900 rpm, it crept up to about 56 deg. after 4 min. of idling. Do you think it can get better with the stock condenser or do I need the parallel flow condenser to get colder air at idle ? Anyway, I think I will move the idle up to 950 rpm when the air is on, that should help cool off the condenser.

I will test it again tomorrow in 100 deg heat. Thanks again.

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 #11 of 29 (permalink) Old Aug 14th, 19, 1:38 AM
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Re: r134a numbers with stock Condenser & replacement POA

The stock condenser is going to drop off in cooling performance anytime it's not getting enough flow. The parallel condenser will drop off much less. If you can bump your airflow through the condenser at slow speeds it will drop off less.

I think you can get your temps down, but need to see gauge readings and ambient to advise. Is the clutch cycling now? If it's not cycling, an adjustment to the low-pressure cycling switch and a bump in high side pressure may be all you need to see better temps at speed. If it cycles too much, you'll often feel the air warm a bit when the compressor shuts off. So a charge where the compressor stays on the longest will result in even cooling but maybe not as cool. Most of these systems will pull down to about 40 degrees if everything is working correctly and there's no extra heat entering the suitcase. Holding at 40 at idle requires a clean evaporator, good parallel flow condenser, and adequate airflow through the condenser. I'll be around tomorrow, my job canceled. Let's see what you come up with.

Do you know which fan clutch you are using? If it's a standard duty, changing to the Heavy Duty or Severe Duty will tighten up the fan at idle, the cost is lower mpg's and more fan noise. It will also kick in sooner.

Sealing the condenser to the rad will increase the pull through the condenser from the fan.
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post #12 of 29 (permalink) Old Aug 14th, 19, 2:03 AM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
The stock condenser is going to drop off in cooling performance anytime it's not getting enough flow. The parallel condenser will drop off much less. If you can bump your airflow through the condenser at slow speeds it will drop off less.

I think you can get your temps down, but need to see gauge readings and ambient to advise. Is the clutch cycling now? If it's not cycling, an adjustment to the low-pressure cycling switch and a bump in high side pressure may be all you need to see better temps at speed. If it cycles too much, you'll often feel the air warm a bit when the compressor shuts off. So a charge where the compressor stays on the longest will result in even cooling but maybe not as cool. Most of these systems will pull down to about 40 degrees if everything is working correctly and there's no extra heat entering the suitcase. Holding at 40 at idle requires a clean evaporator, good parallel flow condenser, and adequate airflow through the condenser. I'll be around tomorrow, my job canceled. Let's see what you come up with.

Do you know which fan clutch you are using? If it's a standard duty, changing to the Heavy Duty or Severe Duty will tighten up the fan at idle, the cost is lower mpg's and more fan noise. It will also kick in sooner.

Sealing the condenser to the rad will increase the pull through the condenser from the fan.
Hi Al, no the Sanden compressor is on all the time, it is not cycling. I am not sure how to adjust the cycling, except the low pressure shut off in the electrical connection on the POA Eliminator. I am running the Hayden heavy duty clutch fan with the stock 7 blade fan and stock shroud. Tomorrow, i will try to get more data. 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
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post #13 of 29 (permalink) Old Aug 14th, 19, 2:42 AM
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Re: r134a numbers with stock Condenser & replacement POA

That low pressure switch on the poa eliminator is what will control all the cycling of your compressor. That pdf shows how to set it. The high pressure switch that should be somewhere in the system will only cycle out if the pressures reach about 400psi on the high side. You should never see this pressure in a properly functioning system, but a poorly functioning condenser could push you up that high.

Are you still running the complete stock wiring system with just the addition of the poa low press switch?

Make sure to purge your gauges before hooking them up. Don't want to be forcing air in each time you hook up. Most of the better gauge sets will hold pressure in the lines. The yellow one will hold pressure if you close and keep the can tap connected. A mistake I've seen made is not closing the valve and removing the empty can, filling the yellow hose with air and not purging. Ends up
pushing a nice amount of air into the system.

We'll catch you tomorrow.
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post #14 of 29 (permalink) Old Aug 14th, 19, 11:06 AM
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Re: r134a numbers with stock Condenser & replacement POA

To help the airflow when you are in a static position. I use the 3947772 fan blade and a clutch from a mid -eightys Suburban. This combo will move a lot of air through the P.Flow cond. ( the mid 80s Burb. fan clutch is a PERFECT match for the 772 blade.)
Its an over the counter part at a Chevy. Dlr. Hey now, Good Luck and be KOOL !
Bob


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post #15 of 29 (permalink) Old Aug 14th, 19, 3:39 PM Thread Starter
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Re: r134a numbers with stock Condenser & replacement POA

Quote:
Originally Posted by DUTCH MAX HEADWORK View Post
That low pressure switch on the poa eliminator is what will control all the cycling of your compressor. That pdf shows how to set it. The high pressure switch that should be somewhere in the system will only cycle out if the pressures reach about 400psi on the high side. You should never see this pressure in a properly functioning system, but a poorly functioning condenser could push you up that high.

Are you still running the complete stock wiring system with just the addition of the poa low press switch?

Make sure to purge your gauges before hooking them up. Don't want to be forcing air in each time you hook up. Most of the better gauge sets will hold pressure in the lines. The yellow one will hold pressure if you close and keep the can tap connected. A mistake I've seen made is not closing the valve and removing the empty can, filling the yellow hose with air and not purging. Ends up
pushing a nice amount of air into the system.

We'll catch you tomorrow.
Hi Al, New test today, here are some pics. Cold Motor shut off, high side and low side showed 92 psi. Here is a pic before starting the motor, you can see my POA eliminator hookup and the sanden compressor is below the alternator. I am running the march serpentine belt system.



Here is a pic of the dryer window after running the air cond. for a while



Ok, here are the numbers I got. The test was done in my garage which was 85 deg.. ambient. No fan in front and not much room for cooling. Big block at 1400 rpm.

low side, high side, center vent temp., time
43, 145, 59, 0 min
40, 148, 53, 1 min
40, 150, 52, 2 min
39, 155, 51, 3 min.
39, 165, 51, 4 min.
41, 175, 53, 5 min.
44, 185, 55, 6 min.
46, 198, 57, 7 min.

Temperature in the garage near the front of the motor after 7 min. is now 107 deg. I shut it down for 5 min. Motor is now warmed up but, not hot.

Restart - Temp is 95 deg. infront of the Chevelle

53, 210, 65, 1 min.
55, 245, 65, 2 min.
55, 250, 65, 3 min.

It does seem that the Expansion valve temp sensor fix helped, but, I am thinking I need a parallel flow condenser, new expansion valve, new dryer.

Note: The Sanden compressor and dryer have been in the Chevelle since 2006, but, have not been used much. I had to get the suitcase/evaporator fan motor, evaporator, heater core all straightened out first. I will have to evacuate the system for the new parts, and I am wondering how to validate that my Sanden compressor is 100 percent ?

I am going for a spin now in the summer heat and see how low the center vent temp goes. To be cont.....

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 14th, 19 at 3:54 PM.
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