I'll give you want I know on this. We use to have a HVAC repair guy active on the forum, however I have not seen him post in a good number of years. He was certified I believe to do refrigerant reclaiming and repair.
You stated your farther ordered a capacitor and some R22 gas. I'm not understanding his thought process, the capacitor is for starting the fan or compressor motor and R22 is the gas in the lines of the system. If the fan or compressor does not want to start, then yes after testing the start capacitor that could show it needed a new capacitor and these are not so bad to install. This gets the motor running.
However the R22 gas, these are sealed system with no service ports on them. I have not done a gas system repair on these before but know some about the process. To do this correctly, first using special reclaiming equipment you have to drain the old R22. Then cut open the system and braze in test ports to charge the system with new R22 to the exact amount by the test gages, then seal off the system and cut out the test ports. If this special equipment and training is not available this is very difficult to recreate. You also should find the issue of low pressure and fix that too which started this in the first place.
If you have an HVAC friend with all this equipment, then ask them to help. Going to a RV dealer they may or may not have this. The cost for this work, if low gas is the problem, should be checked before proceeding. These kind of repairs can sometime outweigh the cost of new unit trying to fix a very old AC unit.
A year ago my AC unit stopped cooling as well and it is not as old as yours. The basic trouble shooting is, when the unit has been running for a good amount of time, say 20 minutes or so and no cooling is felt.
Check the both coils, the inside one and the outside one that are not plugged or really dirty. They can be cleaned. It is also assumed the fan motor also runs. If the coils are clogged this post may help http://www.sunlineclub.com/forums/f7...ics-10405.html
Once past the motors running and the coils are clean enough you are now at the compressor. If you feel the 2 large gas tubes, one coming to the compressor from the inside coil and one leaving the unit going to the outside coil, the temperature should feel very different. One real hot, going to the outside coil and one cooler comeing from the inside coil. If they are both the same temp, then the compressor is not compressing the gas enough from either a leak of coolant (look for oil leaks at a crack in a tube) or the compressor has an internal problem or there is clogged line somewhere.
If you reach the point where there is no real change in the supply and return pipe temp off the compressor, this becomes a turning point. Try and hire an HVAC person to fix your XX year old AC unit for $YYY dollars or invest that money into a new roof unit.
In my case, the tubes where the same temperature and I opted to replace the roof unit. Putting a large service cost into a 13 year old unit did not seem like the better investment verses adding some more to it and resetting the wear clock. This post may help if you choose to go the replace method
Hope this helps.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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