Jump to content

Leaderboard


Popular Content

Showing content with the highest reputation on 06/30/2010 in all areas

  1. 1 point
    I am running for the county board here in Boone county. We were in the our local week early 4th of July parade. This was by far the best day of campaigning, because we worked a truck into the mix.-Brad
  2. 1 point
    Thad makes some very valid points and there are a few more to go with them: In a new system such as yours that is untested, one needs to ensure there is enough lubricating oil within the system. A very good ratio of PAG, or ester oil to refrigerant capacity is seven ounces of oil per pound of refrigerant in the system. Too little oil and the compressor does not last. Typically the aftermarket suppliers are using either a Sanden compressor, or a variant of the type. These have a sump with a plug in the side of the body. With the compressor level, remove the plug, and fill the sump with oil to the bottom of the threads in the body and replace the plug. Remove the plugs in the suction and discharge ports and pour about 1/2 ounce oil in each and turn the compressor clutch slowly over by hand. When you have made about six revolutions of the clutch, install the plugs back into the compressor ports. Now either install onto the engine or place in an out of the way place so you can lose it............ After you mount your condensor, evaporator and ancillary equipment and just before running the linesets, pour about 2 ounces of oil in the condensor, and evaporator with the balance in the receiver/dryer, or accumulator. Figuring about a 2 pound refrigerant capacity system you will now have between 12, and 14 ounces total oil in the system and this is enough to get started. I then install the lineset(s), (lubricate any "O" rings with refrigerant oil) and tighten to proper torque. Use ample clamp to secure the lines from the enging mounted compressor to the evaporator and condensor also. As Thad stated pull the system into a deep vacume in excess of 29.75 inches and let the system dwell with the vacume pump running at least two hours. One step further I take is to introduce 50 psi of nitrogen into the system and allow it to set for at least 30 minutes to extract any remnants of moisture check for leaks/integrity. After passing these tests, the system is again pulled into a vacume for a couple minutes. I then introduce liquid refrigerant into the high side charge port while the refrigerant bottle sets on a calibrated scale. When there has been one pound of liquid refrigerant introduced into the system, I shut the flow off. This is allowed to stabilize and "flash", or evaporate into a gas within the system so the compressor is not "slugged" upon startup. About two minutes is enough but if the system is started immediately and liquid refrigerant hits the compressor, it's bye bye time for the valves in the compressor. At this time you can engage the system and begin to introduce more refrigerant in the form of gas into the low side, (suction port) of the compressor. Dependent upon the ambient temperature of the air will dictate your compressor discharge pressure but stay below 300 psi at all times. Most R-134 systems will not let you exceed 350 psi as a safety precaution and will shut the compressor down by releasing the clutch. With the windows closed in the cabin keep charging and looking for about a 33-35 degree evaporator temperature as indicated on your suction, or low side gauge that is blue in color. Using R-134 refrigerant with an ambient temperature of 90 degrees F, you should be about 255 psi to 270 psi dependent on humidity level. Don't overcharge the system as efficiency degrades quickly and loss of cooling is the result. Watch closely as you near the 33 degree temperature because I've seen several times a guy walk away and introduce more refrigerant than needed with less than desirable results. Most of Red Dot's roof mount units have a built in fan to pull air across the roof mounted condensor so you will not need a fan. If you use a front of radiator mount condensor coil you would need to place a box fan to blow cooling air across the coil. Keep note of how much refrigerant has been introduced into the system via the scale. When your low side suction gauge reads about 30 degrees run a calculation of how much oil the system is still short assuming the seven ounces of oil to refrigerant ratio and continue to introduce the needed amount of oil. The refrigerant will circulate it within the system. Rob
  3. 1 point
    You also have to have it charged and make sure you have the oil charged as well. That might run you upward of $75-$150 depending on the amount of refrigerant used. You can do it yourself but you need to invest in a charging manifold and vacuum pump. I did just that and have successfully charged a few systems myself with great results. Bought a Cooler Master charging manifold for around $80 and a used JB Industries vacuum pump off ebay ($150). JB pumps are made in the USA and they provide part lists and exploded view diagrams to rebuild and service the pump as necessary (http://www.jbind.com/). Charging is simple. Hook both the red high side and blue low side hoses to the AC system and hook the yellow hose to the vacuum pump (some manifolds have 4 hoses one for vacuum and the other for refrigerant). Then make sure your pump is full of oil and then turn it on. Open both the high and low side valves on the manifold to begin the pump down. Give it an hour or two to pull a nice vacuum and also eliminate any moisture and vapor from the system. You should be able to pull and sustain a vacuum of 29 inches of mercury (<20Torr). Then shut both valves on the manifold, disconnect the pump and then connect the yellow line to a can or tank of refrigerant. Start the vehicle and slowly crack the low side valve letting the refrigerant into the low side. This will build up pressure in the low side and charge the system. Sometimes the pressure in the low side gets high enough tso as the refrigerant in the can or tank wont evaporate. That's an easy problem to fix, get a pail or bucket of warm water and submerge the can into the water. This causes the pressure to quickly build from the can forcing it to empty. Keep charging until the low side can run at a stable 40PSI and the high side around 250PSI (that is for R134a). Oh and never charge the system from the high side unless you want the charging can to explode. The equipment cor charging can run you upward of $300 but you can charge any modern refrigeration system. Maybe make a few bucks on the side charging AC systems.
×
×
  • Create New...