Charging your A/C system??


Old 07-15-03, 12:07 PM
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Charging your A/C system??

I would like to recharge my HVAC system. (Trane XL1200 3 ton) But unsure what the gauges should read.

I took the EPA test/s and got my license to purchase HCFC-22.

The gauges currently read 40 psi on the low side and 210 on the high side.

I cleaned the outside (condenser) and the inside (evaporator) coils. The inside coils are cold ( frosty) on the bottom few rows, but the upper 2/3ís are not. The liquid line feels like itís surging a bit. Like there is not enough liquid in the line.

Any help would be appreciated.
Old 07-15-03, 01:50 PM
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In spite of obtaining EPA certification there is an issue of qualification and equipment.

The EPA certification is one that ensures that refrigerants are handled in a proper manner.
Along with that goes the need to have equipment to be able to reclaim and recover refrigerants.
You must also have leak detection equipment and the means to repair leaks.

Juicing up a/c's is no longer acceptable.
Old 07-15-03, 02:08 PM
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lets find that leak first

look for oil on the line at the solder joints, the u bends of the coils and all threaded fittings. also spray them with a soap solution. when you find it you will have to pump down the system (if the leak is not at the outdoor unit) or reclaim the charge if it is. the proper charge will be determined by outdoor temp and indoor wet bulb. you can charge by superheat by subtracting the refrigerant temp at outdoor suction line from the evap temp at that pressure. this will be on the suction guage, the green scale labeled R22. a good rule of thumb is 8 degrees superheat at 72 inddor temp (dry bulb). i would bring the suction pressure up to indoor room temp, then adjust when house cools to 72. look for a high suction with high indor temp, which will drop when indoor temp reduces. get a 72 to 75 suction, watch the head. if this is a TXV, as it well may be, then disregard this advice, as subcooling will be the proper way to charge. nonetheless, look for 72 to 75 suction. if head goes above 240 or so, on that unit, clean the outdoor coil again. that type of coil (spline fin) is VERY suseptible to clogging, use an acid or alkaline based cleaner. GrehH is right, an EPA card does not qualify you to charge units properly, just handle the refrigerant. let us know how it works out.
Old 07-15-03, 02:26 PM
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more info

Thanks for the responses.

The outside temp is 100 degree's. The house temp is 90 degrees. The unit is 12 years old.

I have all the tools you mentioned. Robinair recovery unit, recovery tank, leak detector, oxy/aceteylene, meters, vac pump.
experience lacking obviously.

I know the rules, that was on the test. fix the leaks that are over 15% per year.

The only place with oil is the at the schraeder value. This could be the source of the leak. I will check that tonight.

If the system need to be evacuated to fix the leak, would it be worth it to add a sight glass??

Old 07-15-03, 02:29 PM
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i would not add the sight glass, especially if it is a TXV, you seem qualified, i do not think you will have any problems. that hot inside? run that suction to @ 80 or 82, it will drop when the house cools off.

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