07-16-2015, 01:01 PM
All is operating normally now after lots of noodling and some investment in tools.
The tech came and we ended up recovering the R22 into a container for incineration, we weren't sure of the history or purity of what was in the system. With a gauge set attached to the system and a nitrogen bottle we pushed 340psi into the low pressure line and vented the high pressure line. We got flow through the system. When we shut the N2 off the pressure gradually reduced until it hit 40 psi and then hung up there. We tried several times and got the same result. I decided to work on it myself from this point on which I could do without violating any state or federal laws.
I bought a Goss nitrogen regulator $69, a CPS micron vacuum gauge $150, a FJC 6912 vacuum pump $121, and a yellow Jacket gauge set $95, and some Sil-Fos 15 silver solder - 2 sticks at $8. Sil-Fos 5 is considerably cheaper but harder to work with. I also rented a 40 ft tank of N2 from Airgas for $30. I already had an acetylene torch.
I removed the schrader valves on the access ports and tried blowing 300psi N2 backwards through the system, it worked as before except the pressure did not hang up at 40psi, the pressure just drifted to zero once the N2 was shut off. I then set up a gentle N2 purge of the system and unsoldered the filter drier. I blew out the system with N2 hoping that any debris left in the liquid line would be expelled. I then soldered a new filter drier in place, again with continuous N2 purge. The new one was a Emerson 052S ("05" is the cubic inches of media in the filter, "2" is the number of 1/8inches diameter of inlet and outlet, and "S" indicates the end fittings are for sweated connection. The filter drier was covered in wet rags during the soldering.
I then installed new schader valves with TFE seals, pressurized the system to 200 psi, locked that pressure in and let it sit overnight to check for pressure loss due to leaks, there was no loss. Then I pulled a vacuum down to 300 microns, again that is an indication of no leaks. I disconnected the gauge setup and left a vacuum in the system.
The tech came back this morning and put in enough R22 to give about 8 degrees superheat to the vapor returning from the evaporator to the compressor. I was surprised at how much the vapor temp varied and how long it varied before it settled. Patience is a virtue. Cool air is in the house! I doubt I'm getting the full 13,500 BTU/hr, but I'm getting sufficient.
Something additional I learned along the way. Starting in 2020 it will be illegal to import or manufacture in this country the R22 most of our systems are filled with. While R22 stocks last the price of this stuff will raise dramatically and there is no approved "drop-in" replacement for our split air conditioning systems. We can't reliably convert our systems to the currently used R410a because it operates at high enough pressures to overstress our current components, so we will have to replace the components (compressor, condenser, and evaporator) when R22 is no longer economical. On my coach I believe it will be possible to deconstruct a Dometic Brisk Air rooftop unit built since 2010 and install the components without too much work in the existing locations.
I hope my description of what I went through will be helpful to those facing similar circumstances, though my biggest hope is that you never have to face these circumstances. Then again, I acquired new skills and TOOLS.
The tech came and we ended up recovering the R22 into a container for incineration, we weren't sure of the history or purity of what was in the system. With a gauge set attached to the system and a nitrogen bottle we pushed 340psi into the low pressure line and vented the high pressure line. We got flow through the system. When we shut the N2 off the pressure gradually reduced until it hit 40 psi and then hung up there. We tried several times and got the same result. I decided to work on it myself from this point on which I could do without violating any state or federal laws.
I bought a Goss nitrogen regulator $69, a CPS micron vacuum gauge $150, a FJC 6912 vacuum pump $121, and a yellow Jacket gauge set $95, and some Sil-Fos 15 silver solder - 2 sticks at $8. Sil-Fos 5 is considerably cheaper but harder to work with. I also rented a 40 ft tank of N2 from Airgas for $30. I already had an acetylene torch.
I removed the schrader valves on the access ports and tried blowing 300psi N2 backwards through the system, it worked as before except the pressure did not hang up at 40psi, the pressure just drifted to zero once the N2 was shut off. I then set up a gentle N2 purge of the system and unsoldered the filter drier. I blew out the system with N2 hoping that any debris left in the liquid line would be expelled. I then soldered a new filter drier in place, again with continuous N2 purge. The new one was a Emerson 052S ("05" is the cubic inches of media in the filter, "2" is the number of 1/8inches diameter of inlet and outlet, and "S" indicates the end fittings are for sweated connection. The filter drier was covered in wet rags during the soldering.
I then installed new schader valves with TFE seals, pressurized the system to 200 psi, locked that pressure in and let it sit overnight to check for pressure loss due to leaks, there was no loss. Then I pulled a vacuum down to 300 microns, again that is an indication of no leaks. I disconnected the gauge setup and left a vacuum in the system.
The tech came back this morning and put in enough R22 to give about 8 degrees superheat to the vapor returning from the evaporator to the compressor. I was surprised at how much the vapor temp varied and how long it varied before it settled. Patience is a virtue. Cool air is in the house! I doubt I'm getting the full 13,500 BTU/hr, but I'm getting sufficient.
Something additional I learned along the way. Starting in 2020 it will be illegal to import or manufacture in this country the R22 most of our systems are filled with. While R22 stocks last the price of this stuff will raise dramatically and there is no approved "drop-in" replacement for our split air conditioning systems. We can't reliably convert our systems to the currently used R410a because it operates at high enough pressures to overstress our current components, so we will have to replace the components (compressor, condenser, and evaporator) when R22 is no longer economical. On my coach I believe it will be possible to deconstruct a Dometic Brisk Air rooftop unit built since 2010 and install the components without too much work in the existing locations.
I hope my description of what I went through will be helpful to those facing similar circumstances, though my biggest hope is that you never have to face these circumstances. Then again, I acquired new skills and TOOLS.
Jon Kabbe
1993 coach 337 with Civic towed