I need some advice on converting R12 to R134. Some background. My compressor was locked last year. Thus, I replaced the compressor and drier yesterday. I'm planning to convert to R134. Questions. Do I need to change the expansion valve? Regarding the procedure to evacuate and flushing the system.... Does the exvacuating takes place first or the flushing goes first? Or does really matter?
thanks
91 Q45 AC compressor conversion to R134
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maxnix
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Re: 91 Q45 AC compressor conversion to R134 (tx91q45)
There is a detailed post about this by Q45tech, so try a search.
Evaporator and condenser have to be changed, along with dryer and hoses. Not cheap to do correctly.
Evaporator and condenser have to be changed, along with dryer and hoses. Not cheap to do correctly.
Today I had my 134 evacuated, got a refund, and added Freeze12. Works like a charm. 134 was useless on an 85-degree day with mild humidity. I opened my windows.
Dennis warns in a previous post that the smaller molecules combined with more porous R12 hoses make it prone to leak, and the part of Freeze12 that leaks first is what carries the oil -- possible compressor damage.
"Envirosafe," another R12 alternative, supposedly uses a larger molecule.
Dennis warns in a previous post that the smaller molecules combined with more porous R12 hoses make it prone to leak, and the part of Freeze12 that leaks first is what carries the oil -- possible compressor damage.
"Envirosafe," another R12 alternative, supposedly uses a larger molecule.
The system should be left stock, and any leaks fixed. Even with the cost delta between R-12 and R134a, it's cheaper and safer to keep it R-12, which is more efficient too.
As far as the flush, it should have been done before installing the drier and evacuating the system. Now the system would have to be opened up to do the flush, and the drier will be exposed to humidity, shortening its life. Or are the lines not hooked up yet (drier still capped)?
As far as the flush, it should have been done before installing the drier and evacuating the system. Now the system would have to be opened up to do the flush, and the drier will be exposed to humidity, shortening its life. Or are the lines not hooked up yet (drier still capped)?
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Q45tech
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Re: (DAEDALUS)
The vacuuming is critical as it takes a serious vacuum and time to boil water at room temperature.............how moisture is removed from system interior.
Probably 95% of AC shops don't do it correctly [spend enough time] or use less than optimal equipment which won't pull an as oem vacuum DEPTH.
"Thermistor Vacuum GaugesKeith Johnson of Honda spoke about the importance of thoroughly evacuating A/C systems when parts are replaced. Evacuating an A/C system with a vacuum pump pulls out air and moisture, both are contaminants that can cause problems if left inside the system. Air reduces the cooling efficiency of the system and moisture mixes with refrigerant oil to produce sludge. Moisture also can freeze and plug the expansion valve causing noise, restrictions or a complete blockage.
A pump capable of achieving high vacuum must be used to pull out all of the contaminants. When air is pulled out of the system, it creates a vacuum that causes residual moisture to boil and evaporate. For this to occur, the vacuum pump must be capable of pulling at least 29 in. Hg of vacuum throughout the evacuation process (which normally takes about 30 minutes).
Johnson said the best way to monitor the evacuation process is with a Thermistor Vacuum Gauge that reads in microns (one inch of Mercury equals 25,400 microns). It takes a highly accurate instrument to measure vacuum because even a little pressure left in the system can prevent all of the residual moisture from boiling out. Only a half-inch of mercury of pressure (12,700 microns) can reduce the boiling point of water by over 20° F. Pulling out the last fraction of an inch of pressure is the most critical step in the evacuation process to assure the complete removal of all air and moisture.
After you have pulled a deep vacuum on an A/C system, close all valves and shut off the vacuum pump. A slow rise in pressure (which you can see on the Thermistor Vacuum Gauge) will occur as the residual moisture continues to boil off inside the system. Pulling additional vacuum will get rid of this moisture. The evacuation will not be complete until the system can maintain a stable vacuum reading below 700 microns for at least three minutes.
The time it takes to completely evacuate an A/C system can be reduced by preconditioning the evaporator prior to hooking up the vacuum pump. Preconditioning raises the temperature so the moisture will boil off faster. The easiest way to raise the temperature of the evaporator is to run the engine with the heater on HOT in the RECIRC mode. Turn the blower fan to HIGH and close all doors and windows. When the engine reaches normal operating temperature, the evaporator will be thoroughly preheated and ready to evacuate.
Johnson said if you have difficulty maintaining a stable deep vacuum, there may be a leak in the A/C system, the vacuum pump or the equipment connections. Leak testing should be done prior to evacuating the system because evacuation is not always a reliable way to locate or even identify a small leak in an A/C system. Seals and O-rings that leak under pressure may move under evacuation and not leak."
Probably 95% of AC shops don't do it correctly [spend enough time] or use less than optimal equipment which won't pull an as oem vacuum DEPTH.
"Thermistor Vacuum GaugesKeith Johnson of Honda spoke about the importance of thoroughly evacuating A/C systems when parts are replaced. Evacuating an A/C system with a vacuum pump pulls out air and moisture, both are contaminants that can cause problems if left inside the system. Air reduces the cooling efficiency of the system and moisture mixes with refrigerant oil to produce sludge. Moisture also can freeze and plug the expansion valve causing noise, restrictions or a complete blockage.
A pump capable of achieving high vacuum must be used to pull out all of the contaminants. When air is pulled out of the system, it creates a vacuum that causes residual moisture to boil and evaporate. For this to occur, the vacuum pump must be capable of pulling at least 29 in. Hg of vacuum throughout the evacuation process (which normally takes about 30 minutes).
Johnson said the best way to monitor the evacuation process is with a Thermistor Vacuum Gauge that reads in microns (one inch of Mercury equals 25,400 microns). It takes a highly accurate instrument to measure vacuum because even a little pressure left in the system can prevent all of the residual moisture from boiling out. Only a half-inch of mercury of pressure (12,700 microns) can reduce the boiling point of water by over 20° F. Pulling out the last fraction of an inch of pressure is the most critical step in the evacuation process to assure the complete removal of all air and moisture.
After you have pulled a deep vacuum on an A/C system, close all valves and shut off the vacuum pump. A slow rise in pressure (which you can see on the Thermistor Vacuum Gauge) will occur as the residual moisture continues to boil off inside the system. Pulling additional vacuum will get rid of this moisture. The evacuation will not be complete until the system can maintain a stable vacuum reading below 700 microns for at least three minutes.
The time it takes to completely evacuate an A/C system can be reduced by preconditioning the evaporator prior to hooking up the vacuum pump. Preconditioning raises the temperature so the moisture will boil off faster. The easiest way to raise the temperature of the evaporator is to run the engine with the heater on HOT in the RECIRC mode. Turn the blower fan to HIGH and close all doors and windows. When the engine reaches normal operating temperature, the evaporator will be thoroughly preheated and ready to evacuate.
Johnson said if you have difficulty maintaining a stable deep vacuum, there may be a leak in the A/C system, the vacuum pump or the equipment connections. Leak testing should be done prior to evacuating the system because evacuation is not always a reliable way to locate or even identify a small leak in an A/C system. Seals and O-rings that leak under pressure may move under evacuation and not leak."