08-03-2015, 01:21 PM
Having crawled around the system for awhile here is what I think I found. The fittings on the system are consistent with R-12. Starting at the compressor the system seems to be configured as a hybrid: compressor - condenser coil with electric fans - accumulator/drier - orifice - evaporator. I can find no pressure switches connected to the system so unless there is a timer somewhere when the A/C is turned on the compressor runs continuously. With the A/C turned on the compressor clutch does not engage, I need to follow the electrical to determine why.
In regards to refrigerant there are options. Each of us gets to choose what risks and benefits make sense.
1) Stick with R-12 and risk damaging the ozone layer with expected leaks. Ozone layer destruction is the justification for all the restrictions on R-12. This system has a large number of mechanical threaded connections plus a rotating compressor shaft that can leak.
2) Fill the system with propane/isobutane. This is illegal according to EPA with the rationale that it is flammable and could cause considerable burning in an accident. It cools better and runs at a lower pressure than R-12, better efficiency. Our systems would require about 4lbs of the stuff. This refrigerant has essentially zero impact on global warming if leaked to the atmosphere.
3)Convert the system to R-134a, the currently used automotive refrigerant. The system will lose some cooling and will run at a slightly higher pressure, though not enough so to create big problems for the installed equipment. There is some debate about whether the hoses need changing with the latest consensus that if the hoses have been run with R-12 for some time they will be coated with enough oil to prevent the migration of the smaller R-134a molecules through the hose. If you have a hose leak then you would have to install hoses designed for R-134a, they have a nylon liner that is impervious to the new stuff. R-134a will contribute to global warming in a small way if leaked to the atmosphere and while not inflammable it can smolder a bit if released. Work is underway to eliminate the use of R-134a in vehicle systems.
4) Convert the system to HFC-152a. This material is commonly used in dust blower cans to clean your keyboard and other electronics. It has a far lower global warming impact than R-134a. However it is somewhat more flammable than R-134a and autos being designed to use it will have vent valves releasing to wheel wells in case of an accident. The fire risk is not great, but not nonexistent. It will cool better and run at slightly lower pressure. The existing hoses are just fine since the molecules are larger than R-12. There are can taps that squeeze onto the side of dust blower cans to allow the filling of the system. EPA has not approved the use of HFC-152a for vehicles.
I'm providing this review for information purposes only. I'm not recommending any approach, each owner needs to decide what tradeoffs make sense, and there are tradeoffs to every approach. I will say that if I were to use any approach other than R-12 or R-134a I would evacuate the refrigerant prior to selling the coach to minimize my liability.
From what I can tell thus far, the dash air capacity is about equivalent to one house air conditioner.
If you are aware that something I've said here is in error please let me know and I'll post a corrective post.
In regards to refrigerant there are options. Each of us gets to choose what risks and benefits make sense.
1) Stick with R-12 and risk damaging the ozone layer with expected leaks. Ozone layer destruction is the justification for all the restrictions on R-12. This system has a large number of mechanical threaded connections plus a rotating compressor shaft that can leak.
2) Fill the system with propane/isobutane. This is illegal according to EPA with the rationale that it is flammable and could cause considerable burning in an accident. It cools better and runs at a lower pressure than R-12, better efficiency. Our systems would require about 4lbs of the stuff. This refrigerant has essentially zero impact on global warming if leaked to the atmosphere.
3)Convert the system to R-134a, the currently used automotive refrigerant. The system will lose some cooling and will run at a slightly higher pressure, though not enough so to create big problems for the installed equipment. There is some debate about whether the hoses need changing with the latest consensus that if the hoses have been run with R-12 for some time they will be coated with enough oil to prevent the migration of the smaller R-134a molecules through the hose. If you have a hose leak then you would have to install hoses designed for R-134a, they have a nylon liner that is impervious to the new stuff. R-134a will contribute to global warming in a small way if leaked to the atmosphere and while not inflammable it can smolder a bit if released. Work is underway to eliminate the use of R-134a in vehicle systems.
4) Convert the system to HFC-152a. This material is commonly used in dust blower cans to clean your keyboard and other electronics. It has a far lower global warming impact than R-134a. However it is somewhat more flammable than R-134a and autos being designed to use it will have vent valves releasing to wheel wells in case of an accident. The fire risk is not great, but not nonexistent. It will cool better and run at slightly lower pressure. The existing hoses are just fine since the molecules are larger than R-12. There are can taps that squeeze onto the side of dust blower cans to allow the filling of the system. EPA has not approved the use of HFC-152a for vehicles.
I'm providing this review for information purposes only. I'm not recommending any approach, each owner needs to decide what tradeoffs make sense, and there are tradeoffs to every approach. I will say that if I were to use any approach other than R-12 or R-134a I would evacuate the refrigerant prior to selling the coach to minimize my liability.
From what I can tell thus far, the dash air capacity is about equivalent to one house air conditioner.
If you are aware that something I've said here is in error please let me know and I'll post a corrective post.
Jon Kabbe
1993 coach 337 with Civic towed