freq

iTrader: (6)

I'm having some probs recharging my ac.
When I attach the cans of oil and refrigerant to the low pressure nipple refrigerant doesn't get pulled into the system.
I read somewhere that when the system is real low on refrigerant, the compressor doesn't kick on.
I had a crack in one of my ac pipes, so there was no pressure at all in the system.
I'm thinking that maybe since the compressor won't kick on because of low pressure, it won't suck the new refrigerant in?

2713ddddavid

iTrader: (1)

If the system leaked all refigerant out through a crack in the lines, first you must replace the line. Next, and this is VERY, VERY important, you must have the system evacuated with a REAL vacuum pump. If you do not know what you are doing I advise you to find a quailified A/C mechanic. Otherwise you will cause much larger problems. (see sig.)

And yes I am a 25 yr service tech for a cooling contractor.
Good luck with it though, a working A/C is a blessing, especially in traffic

freq

iTrader: (6)

Any ideas why the refrigerant wouldn't get pulled into the system?

2713ddddavid

iTrader: (1)

The compressor must be running for refrigerant to be pulled into the system. There is a low pressure switch in the circuit to protect from operation with no/low refrigerant.
If you try to recharge the system from completly flat (0 psi) without evacuating with a vacuum pump, the high side pressures will be so high that the system will damage itself (o-rings, hoses etc will leak or pop)
I`m not trying to sound like an *** but it sounds to me from the questions you`ve asked that you should really leave this to someone that has the experiance and equipment to get it right. It will save you money and time in the long run.

freq

iTrader: (6)

No, you don't sound like an ***. I don't know the first thing about A/C.
But in my experience it's best to have a full understanding of the problem and the fix before I either:
1. attempt the repair myself or
2. give it to a mechanic trusting that the price he's quoting me actually reflects the work that he's doing. ..know what I mean? ;-)
Thanks for the info.

2713ddddavid

iTrader: (1)

I can dig it. Measure twice and cut once is a good policy
It is unfortunant that mechanics overcharge like that, and A/C work is always much more expensive than just about any other automotive work.

If all you have done is replace a refigerant line then what you need to do/have done
is,
1. replace the receiver/dryer canister.
this is SUPPOSED to be done anytime the system is opened up to the atmosphere.

2. evacuate the system with a proper vacuum pump down to between 28-30 inches below atmosphere and once down that low the pump should run for about 45 minutes. If you do not have the adapter that will let you attach a guage set to the high side service port then you CAN evacuate through the low side only but I`d let the Vacuum pump run twice as long.

3. once evacuated you will want to recharge using a charging scale, or dial-a-charge. I believe our cars take 1 LB 12 Oz of R12 refrigerant (1.75Lbs). If you are converting to R134a refrigerant then only put 75% of the R12 charge weight. You can add a little PAG oil with the R134a but don`t put more than about 4 Oz. If you are lucky enought to have access to 12 refrigerant then add a little mineral oil to the system.

I`m not sure where the low pressure switch on our systems but if the system is still working right electroniclly you should be able to add refrigerant a little at a time as the compressor cycles on and off. After a certian point it will stay running for you.