R-134a Conversion Problems - Please help!
08-02-2002, 05:01 PM
#16
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John-
Don't know if your condenser would fit but I may be looking at replacing. Mine was repaired, cleaned and leak tested for $25 by a reputable radiator repair shop (while I waited). I saw a lot of AC condensers there. I used a flush gun with Kwik-Solv and 150psi, flushing both directions 6 times, then forward direction 3 times, chasing with nitrogen until clear and clean. I put the system back together with another new drier, replacing oil lost in the drier and condenser. Pressurized with nitrogen and it held. Pulled a deep vacuum and it held overnight. Added two cans (24oz.) of R-134a. Pressures went to 60psi on low side and 325psi on high side. Ambient temp in my shop was 110F. I suspect an orifice was created at the repair site inside the condenser coil which is causing the high pressure. It blows cool (not cold) 70 degrees front vent temp, 60 degrees rear vent temp. I am so glad to have some cool air after being without for so long, and so exhausted from struggling with this for a week and a half, that I am going to just drive it and enjoy it for awhile. I hope the compressor will not be damaged. At least it holds a charge now and all leaks are fixed. But, if I didn't have gauges I would be tempted to add a little more refrigerant.
Don't know if your condenser would fit but I may be looking at replacing. Mine was repaired, cleaned and leak tested for $25 by a reputable radiator repair shop (while I waited). I saw a lot of AC condensers there. I used a flush gun with Kwik-Solv and 150psi, flushing both directions 6 times, then forward direction 3 times, chasing with nitrogen until clear and clean. I put the system back together with another new drier, replacing oil lost in the drier and condenser. Pressurized with nitrogen and it held. Pulled a deep vacuum and it held overnight. Added two cans (24oz.) of R-134a. Pressures went to 60psi on low side and 325psi on high side. Ambient temp in my shop was 110F. I suspect an orifice was created at the repair site inside the condenser coil which is causing the high pressure. It blows cool (not cold) 70 degrees front vent temp, 60 degrees rear vent temp. I am so glad to have some cool air after being without for so long, and so exhausted from struggling with this for a week and a half, that I am going to just drive it and enjoy it for awhile. I hope the compressor will not be damaged. At least it holds a charge now and all leaks are fixed. But, if I didn't have gauges I would be tempted to add a little more refrigerant.
08-02-2002, 07:44 PM
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Fixed from a reputable facility, and cheap too. Lucky you. Things work out great sometimes. Good luck with it. I am sure it will be fine. What caused the original hole in the condensor??
John D.
John D.
08-03-2002, 12:17 AM
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John-
See the photo earlier in this thread. The condenser was in contact with the PS fluid cooling loop and eventually rubbed a hole. After pulling the condenser I could see that the PS fluid cooling pipe was also pushing against the radiator. I re-arranged things as best I could then inserted some pieces of heater hose at the contact points. This was also an excellent opportunity to do some cleaning in the area in front of the radiator which was had layers of oil, ATF, dirt, leaves, bugs, feathers, cigarette butts, etc. Hey! There's paint under there!
See the photo earlier in this thread. The condenser was in contact with the PS fluid cooling loop and eventually rubbed a hole. After pulling the condenser I could see that the PS fluid cooling pipe was also pushing against the radiator. I re-arranged things as best I could then inserted some pieces of heater hose at the contact points. This was also an excellent opportunity to do some cleaning in the area in front of the radiator which was had layers of oil, ATF, dirt, leaves, bugs, feathers, cigarette butts, etc. Hey! There's paint under there!
08-03-2002, 02:46 AM
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Steve, sorry!!
The pics didn't pull up on my computer, needed to restore to an earlier date. In my opinion you did the best thing by repairing the leak. Looking at the pics, no furthewr problems should be anticipated.
There are test kits available at refrigeration distribution houses to test acid levels in the a/c system. 99% of automobiles do not have to worry about acid in the a/c system.
Phosgen (spelling escapes me at this time, excuse me) gas is created in a refrigeration system basically , by brazing a repair on lines or other components and not running dry nitrogen or another inert gas thru the system while brazing. The inert gas keeps the oil, small amounts of refrigerant and high heat to mix creating the gas. The dry nitrogen acts like a minor purge. When brazing you just need 1 PSI of inert gas or even less to purge while brazing a repair.
The acid is created by the mixture of the moisture in the air, refrigeration and metal on the inside of the system. The best way not to worry about acid in the system is to dehydrate the system (pull a vac) below 500 micron, after a repair and or before charging any system.
John D.
The pics didn't pull up on my computer, needed to restore to an earlier date. In my opinion you did the best thing by repairing the leak. Looking at the pics, no furthewr problems should be anticipated.
There are test kits available at refrigeration distribution houses to test acid levels in the a/c system. 99% of automobiles do not have to worry about acid in the a/c system.
Phosgen (spelling escapes me at this time, excuse me) gas is created in a refrigeration system basically , by brazing a repair on lines or other components and not running dry nitrogen or another inert gas thru the system while brazing. The inert gas keeps the oil, small amounts of refrigerant and high heat to mix creating the gas. The dry nitrogen acts like a minor purge. When brazing you just need 1 PSI of inert gas or even less to purge while brazing a repair.
The acid is created by the mixture of the moisture in the air, refrigeration and metal on the inside of the system. The best way not to worry about acid in the system is to dehydrate the system (pull a vac) below 500 micron, after a repair and or before charging any system.
John D.
08-03-2002, 11:12 AM
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"Added two cans (24oz.) of R-134a. Pressures went to 60psi on low side and 325psi on high side. Ambient temp in my shop was 110F. I suspect an orifice was created at the repair site inside the condenser coil which is causing the high pressure. It blows cool (not cold) 70 degrees front vent temp, 60 degrees rear vent temp."
A puzzling situation, with some conflicting facts.
1) Normal R-134a charge should be 80% - 85% of the R-12 charge. This puts the expected R-134a charge for your car at about 36 ounces. You put in 24 ounces, but the gauge readings make the system look overcharged. The system should be undercharged, with much lower pressures on both sides, and poor cooling with both system on.
2) Your system has one compressor, one condensor, but two expansion valves and evaporators. Each expansion valve should take the high-pressure liquid and control the spray into the evaporator so as to hold somewhere around 30 psi in the evaporator. If you had a bad expansion valve (locked open) you might expect the higher-than-normal low side pressures that you are seeing, but it is pretty unlikey that both expansion valves failed at the same time in the same way.
The pressure reading is a combination of both valves, but the output temp readings on both evaporators are very consistent with the reported low side pressure. This makes it appear that you truly have higher-than-normal low side pressure.
3) The high side pressures are highly variable, with ambient temp and air flow over the condensor being the main factors. It would be interesting to know what the high side pressures are at highway speeds. It would also be interesting to spray a mist of water on the condensor and see what the pressures and output temps are. You may have airflow problems, perhaps dirty condensor and/or radiator, fans not at full speed, etc.
4) I have difficulty in believing that you would not have noticed a blockage in the condensor coil during the cleaning operation. Any significant blockage would be very apparent.
My guesses at the moment are:
High ambient temps and poor airflow are cousing the high high side pressures.
One of your expansion valves, probably the front, is locked full open, allowing the high low side pressure to feed back to the rear evaporator from the common low side tube going to the compressor.
Try this:
1) Check the space between the condensor and radiator for leaves and crud.
2) Set the system up with both systems on full, water mist on the condensor, engine at a constant 2000 RPM. Hold it that way for several minutes and then check the pressures and output temps. If you get good cooling at one system and not the other, change the expansion valve and charge the system. I would expect much lower pressures on both sides, and fair cooling at one system and poor cooling at the other.
A puzzling situation, with some conflicting facts.
1) Normal R-134a charge should be 80% - 85% of the R-12 charge. This puts the expected R-134a charge for your car at about 36 ounces. You put in 24 ounces, but the gauge readings make the system look overcharged. The system should be undercharged, with much lower pressures on both sides, and poor cooling with both system on.
2) Your system has one compressor, one condensor, but two expansion valves and evaporators. Each expansion valve should take the high-pressure liquid and control the spray into the evaporator so as to hold somewhere around 30 psi in the evaporator. If you had a bad expansion valve (locked open) you might expect the higher-than-normal low side pressures that you are seeing, but it is pretty unlikey that both expansion valves failed at the same time in the same way.
The pressure reading is a combination of both valves, but the output temp readings on both evaporators are very consistent with the reported low side pressure. This makes it appear that you truly have higher-than-normal low side pressure.
3) The high side pressures are highly variable, with ambient temp and air flow over the condensor being the main factors. It would be interesting to know what the high side pressures are at highway speeds. It would also be interesting to spray a mist of water on the condensor and see what the pressures and output temps are. You may have airflow problems, perhaps dirty condensor and/or radiator, fans not at full speed, etc.
4) I have difficulty in believing that you would not have noticed a blockage in the condensor coil during the cleaning operation. Any significant blockage would be very apparent.
My guesses at the moment are:
High ambient temps and poor airflow are cousing the high high side pressures.
One of your expansion valves, probably the front, is locked full open, allowing the high low side pressure to feed back to the rear evaporator from the common low side tube going to the compressor.
Try this:
1) Check the space between the condensor and radiator for leaves and crud.
2) Set the system up with both systems on full, water mist on the condensor, engine at a constant 2000 RPM. Hold it that way for several minutes and then check the pressures and output temps. If you get good cooling at one system and not the other, change the expansion valve and charge the system. I would expect much lower pressures on both sides, and fair cooling at one system and poor cooling at the other.
08-04-2002, 03:21 AM
#21
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Wally-
1) R-12 capacity is 37oz. so I expected to use 30-31oz. of R-134a or 2 1/2 12oz. cans. So as far as refrigerant capacity, I am undercharged. The first can went into the evacuated system quickly as a liquid and was enough to run the compressor without jumpering when starting the second can. It took a long time for the second can to go in.
2) Except for the leak in the condenser, the AC cooled fine with R-12 before the conversion. Unfortunately I did not obtain pressure readings while it was still functioning with R-12. I did not flush or attempt to clean the expansion valves other than wiping them and making sure the o-ring seats were clean.
3) The wall thermometer 6ft. away from the car read 110F, so it is possible that ambient temperature in the engine compartment near the condenser was as much as 150F. At 2.2 times ambient temp, a high side pressure of 300+ may be about right. I had a fan blowing through the vent flaps which were fully open. The car's electric fans are operating properly and the radiator and condenser are clean. The compressor was not cutting out. I cleaned road debri from between the condenser and radiator during reassembly.
4) After the condenser was repaired, I could hear what sounded like a tiny solder ball that I could roll from one end to the other by tipping. I tried to roll it through the tubing and out one end but was not successful. After repeated flushing (with the condenser held flat/parallel to the ground), I could not hear any more debri rolling around inside the coils. I believe it was flushed out.
I will try the water mist on the condenser tomorrow and obtain new readings.
1) R-12 capacity is 37oz. so I expected to use 30-31oz. of R-134a or 2 1/2 12oz. cans. So as far as refrigerant capacity, I am undercharged. The first can went into the evacuated system quickly as a liquid and was enough to run the compressor without jumpering when starting the second can. It took a long time for the second can to go in.
2) Except for the leak in the condenser, the AC cooled fine with R-12 before the conversion. Unfortunately I did not obtain pressure readings while it was still functioning with R-12. I did not flush or attempt to clean the expansion valves other than wiping them and making sure the o-ring seats were clean.
3) The wall thermometer 6ft. away from the car read 110F, so it is possible that ambient temperature in the engine compartment near the condenser was as much as 150F. At 2.2 times ambient temp, a high side pressure of 300+ may be about right. I had a fan blowing through the vent flaps which were fully open. The car's electric fans are operating properly and the radiator and condenser are clean. The compressor was not cutting out. I cleaned road debri from between the condenser and radiator during reassembly.
4) After the condenser was repaired, I could hear what sounded like a tiny solder ball that I could roll from one end to the other by tipping. I tried to roll it through the tubing and out one end but was not successful. After repeated flushing (with the condenser held flat/parallel to the ground), I could not hear any more debri rolling around inside the coils. I believe it was flushed out.
I will try the water mist on the condenser tomorrow and obtain new readings.
08-04-2002, 10:49 AM
#22
Three Wheelin'
[quote] The first can went into the evacuated system quickly as a liquid <hr></blockquote>
DOZMAN?? is this proper for R134A?
I charge R12 and R134 as a gas, first can slowly into the vacuum.
Greg
DOZMAN?? is this proper for R134A?
I charge R12 and R134 as a gas, first can slowly into the vacuum.
Greg
08-04-2002, 11:41 AM
#23
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The 37 ounces of R-12 is correct for the cars without the rear air. With the rear air, you should have about 43 ounces of R-12, which normally converts to 36 ounces (3 cans @ 12 ounces) of R-134a. This means that you are undercharged even more than you thought.
I doubt that a small solder ball would create any significant blockage in the condensor. If there is a blockage anywhere in the high pressure side, you will often find a noticeable temperature difference on each side of the blockage - hot before the blockage, cooler after it.
The only reason to charge as gas is to avoid "hydraulicing" or "slugging" the compressor - that is, getting liquid into ta cylinder and locking (if you are lucky) or destroying (if you are unlucky) the compressor. The freon liquid will boil off as you put it into the system - some in the gauge hoses, some in the system before it gets to the compressor.
Charging with liquid is faster. Some refrigerants must be charged as liquids.
For example, some of the blended refrigerants must go as liquids, as otherwise the lower-boiling-point constituents will go in first, and you may end up with the wrong proportions of refigerants.
Some of the R-134a conversion kits include oil and stop-leak in the refigerant, and if you charge as gas, you will leave some of the oil in the can.
Bottom line - charging as gas is safer but slower with a pure refrigerant, while charging as a liquid is often required or preferable, but you have to be careful to avoid slugging the compressor.
I doubt that a small solder ball would create any significant blockage in the condensor. If there is a blockage anywhere in the high pressure side, you will often find a noticeable temperature difference on each side of the blockage - hot before the blockage, cooler after it.
The only reason to charge as gas is to avoid "hydraulicing" or "slugging" the compressor - that is, getting liquid into ta cylinder and locking (if you are lucky) or destroying (if you are unlucky) the compressor. The freon liquid will boil off as you put it into the system - some in the gauge hoses, some in the system before it gets to the compressor.
Charging with liquid is faster. Some refrigerants must be charged as liquids.
For example, some of the blended refrigerants must go as liquids, as otherwise the lower-boiling-point constituents will go in first, and you may end up with the wrong proportions of refigerants.
Some of the R-134a conversion kits include oil and stop-leak in the refigerant, and if you charge as gas, you will leave some of the oil in the can.
Bottom line - charging as gas is safer but slower with a pure refrigerant, while charging as a liquid is often required or preferable, but you have to be careful to avoid slugging the compressor.
08-04-2002, 03:32 PM
#24
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I went out first thing this morning and hooked up the gauges with the car outside in the shade with the water hose handy. Static hi/lo press, engine off: 90psi. Ambient temp 92F. Started the engine with front and rear AC on full, windows open. 48psi/lo, 200psi/hi @ 1000rpm. 36psi/lo, 230psi/hi @ 2000rpm. With engine at 2000rpm, I charged in about 8oz. R-134a (total charge now 32oz). Hi side went to 325psi. Water spray into front of condenser dropped it to 250psi. By this time, ambient temp. was 110F. Vent temps - 68F front, 56F rear. At 2000rpm there was solid fizz in the sight glass. When returned to idle 750rpm sight glass was clear. Lo side 55psi, hi side 300psi.
That's it. As long as I can drive around when it's 100+ outside and not break a sweat, I am satisfied. Engine temp stays two needle widths below top white line. The thought crossed my mind to convert back to R-12 now that my system is tight. Is the polyoester 100 compatible?
That's it. As long as I can drive around when it's 100+ outside and not break a sweat, I am satisfied. Engine temp stays two needle widths below top white line. The thought crossed my mind to convert back to R-12 now that my system is tight. Is the polyoester 100 compatible?
