|
You charge until the high side pressure (while compressor running) reaches 2.2 times the ambient tempreature in farenheit. This is charging by pressure. \] Going back to chemistry and physics we remember the relationship between temp and pressure.
This means that if it's 75 degress for example (you need to do this outdoors), then you continue adding r134 until the high side pressure reading reaches 75x2.2 = 165 PSI. Verify with a vent thermometer of course.
The low side could be around 35ish... your compressor will probably be cyling on only around 50% of the time.
I assume you had a vacuum pulled before charging, if not your system will/can freeze up and not function properly, as well will degrade and corrode due to internal humidity.
Depending on the system, its components, and the actual amount of oil charge (make sure you have the right oil for R134 and you dumped out or better flushed out the old mineral oil), you can probably use around 30ish ounces (3ish cans?) as an estimate.
Note R134 is picky for the charge amount. Too much or too little can afect performance easily.
I did mine last year (89) similar to your job, new high pressure hose, dryer, exp valve, a few orings, and new oil and fittings . Good job, charge seems to have held well through the nasty winter. The performance of my R134 is so-so, mainly due to the inefficient condesner and evaporator. Might leave it alone this summer, or convert to R12, or...
Good job! A/C is not that difficult, if you follow simple rules and aquire the necesasry tools.
Greg Mustang
Montreal - Ottawa
Canada
|
