You should fill the freon by weight, not pressure, as long as you are starting "dry". Look up the capacity in JTIS, but I think it corresponds to about two small cans of Freon. You should also be careful to purge each line of the manifold (Gauge set) for best results. If you know someone who is experienced with filling a system, this is a good job to get help and advice for your first effort. Otherwise, read, read, read.

 

Perhaps not what you want to hear....but if the system was open to the atmosphere for any appreciable length of time, in addition to replacing the rec/drier, you really ought pull the compressor, drain the oil, and replace with a like amount of PAG 100. The oil is highly hygroscopic and while pulling a 30 min vacuum or so will evacuate moisture from the system, it won't pull it out of the oil. Then add a "smidge" to replace the oil lost in the old drier...overall, you'll still have residual (and moisture-laden) oil in the condenser, evap, and lines, so total "new" oil should not be quite as much as the specified oil amount on the vehicle tag.....if you drain more than that from the compressor....someone has over-oiled it at some point...

 

If the evacuation unit you are hiring has provision to attach your gas canister you will only need to purge the hose from canister to gas valve . If you are connecting directly from the can loosen the hose fitting at the compressor enough so that it is not pushing on the valve , open can until gas is escaping and nip up the hose fitting. Gas and gauges are not available in oz unless you are a licensed or what ever user so I am not familiar with them . Back in the day if there was no sight glass a system would be depressurised , evacuated and then the recharge station would convert the weight of the gas needed into volume , set on the ambient temp at that time . Gauges were used for diagnostics but they are now used to also determine how much gas , via pressure , is needed normally a high and low gauge , if both read low gas is low but could also indicate another problem ! how they tell the difference beats me , weight has to be more accurate .Did you put more oil in the system ? every component will retain a certain amount of oil which has to be replaced , as mentioned before , there maybe some info in the T&Bs If not I can give you a ball park ,do not put more than stipulated . PAG 100 was mentioned earlier and if that is the oil that is in your system it is critical that the same oil is used , A/C oils are NOT all compatible .Unfortunately even if all the components were removed you still could not drain all the oil out so draining just the compressor would only be a portion of the total , as stated earlier the oil will attract moisture so if it were my car , I would put around 50% of the gas into the system start the car and leave at idle , do NOT rev the car , for a couple of minutes turn off and start the evacuation . Remember that you can overfill a system even with the compressor turned of .I know that the recommendation is holding the engine revs around 1200- 1500 I hold it steady at around 1000 . Put about 50% of the gas in before staring up this will ensure lubrication for the compressor . Do NOT use a R12 gas leak detector to check R134 , big bang possible , use soapy water , basic but reliable. I cannot think of anything else to tell you at the moment but I hope we hear how every thing turns out .

 

The extra oil is only to compensate for what would have remained in the receiver / dryer.

 

It turns out the potentiometer is the rotary switch in the center that goes from red to blue and this was out of spec electrically. We got one from the UK in 2 days through the dealer. Also, he replaced the o-rings and drained and refilled again. There are no codes on the PDU and it does get cold although not immediately, like in a minute. I'm going to let it go a couple of weeks and see if it works better with use