A/C Dryer question.
 

I'm going to replace the a/c dryer in my 1999 2500 and have a quick question. After installing and pulling a vacuum then refilling do I have to add oil to the system? I know there's oil in the compressor. I have a can of pressurized oil just would like to know if it is needed or if the oil in the comp. all that is needed in the system.
Thanks in advance!!

Is the orfice tube replaceable? I have read that you have to replace the whole H/P line is this true?
And what should the high and low pressures be when system is full?

The fixed orifice is located in the HP/liquid line and the line must be replaced as one, there is noway around it, but if you are changing the accumulator/receiver/dryer for a reason I would definitely replace the orifice tube. There is a table that says how much oil to add for each different component that's replaced for an accumulator replacement it says add 2 fl oz refrigeration oil..

Thanks that's what I have come up with also!!

Mine went yesterday so I've been online all day researching...I think my evap might have gone again but haven't fully diagnosed yet.
ANYWAY.
I found a couple of commercial manuals and walk throughs like one from AriaZone, an equipment manufacturer.
They all recommend adding oil when changing out any parts.
rule of thumb for a
filter drier was 25 ccs
blown hose 50 cc ,
accumulator 40 cc
Evap 40 cc
and figuring out how much to add to a compressor by measuring how much you get out of the old part plus adding a little (10 cc) for internal oils retained in the parts.

I might caution that too much oil is bad, so is too little but you can use an oil injector to add, to remove it's probably means a tear down. Just replacing a leaking hose shouldn't need any extra oil but replacing a blown hose means the refrigerant emptied out quickly taking oil with it, so knowing the history of the system is pretty vital.

An A/C guy at work told my to err on the side with more oil. Unless you go crazy with it extra oil will go through the system and will only degrade the cooling, to little and the stuff breaks down too fast from heat and you will cook the compressor.
Both my evap and the high pressure hose from the pump to the condenser went. The evap was a little corroded and I helped the hose go bad. My bypass oil system has kevlar jacketed hoses and they were rubbing on the aluminum tubing right were it comes from the pump. When I shifted the hose to get it out of my way I must have stressed the thin spot and it holed. I did get oil mist over everything.You have to buy both high pressure hoses because the pump side is a cast aluminum plate with both hoses welded to it.
Oh well. 6 bucks for a can of oil, $65 for the evap and $90 for the hose set. Now I get 38 degree air when the fan is on low and 45 degrees on all out....I'm a cold and happy guy.:cool: