mikesignal

I finished my evaporator and heater core install. Now I need to recharge my a/c. The guy at the auto parts store recommended I take it to a shop and have them vacuum and recharge it, and to make sure they put oil in.

I guess my questions are: why does it have to be vacuumed and can I do it myself? or can I just recharge it?

sorry, I don't know much about a/c systems

RTorrez1

Taking it in would be your best bet. They need to get all of the air out of the system with a good vacuum pump. If you don't get the air out your ac won't last very long and you can cause damage to it. Plus they can put the correct amount of oil and the correct PSI of freon. You can do it if you have a good vacuum pump. A good one is a little pricy.

Pelican

It needs to be vacuumed because it has air plus an unknown quantity of residual 134a and oil in the system. You can vacuum it yourself if you obtain a pump but I would just let a shop do it.

If you are in money saving mode, you can charge it yourself after adding the proper amount of the correct oil. It may or may not work after this depending on the condition of the system.

It takes some patience and luck to get a properly functioning system without really knowing what you are doing but it is possible to do so. I've charged three systems from scratch with simple kits from Walmart/parts stores and all have performed adequately in the hellish southeast Texas summers for from 5 to 8 years.

Are you a gambler? -- your choice.

Edit: I see I crossed with RTorrez1. I'm not sure where Riviera is but I'm sure he also appreciates a really cold A/C....

mikesignal

I've got a new compressor and new dryer too. I guess I will just take it in. I don't want to screw it up. thanks for the info.

Muaddib420

You did all this work, might as well charge it right. They will pull a vacuum and remove air leaving more room for 134.

djb383

U need to turn the new compressor upside down and drain any/all oil out. Need to flush the condenser and hose manifold with a/c flush and blow it out with compressed air. Basically need to flush/clean any components that are not new. U also need to replace the liquid line/orifice tube. Now the system will be completely dry/empty of both oil, refrigerant, crud, etc. Measure/add precisely the amount of PAG oil to the system and have the shop pull a vacuum and exactly the number of lbs/ounces of refrigerant shown on the sticker under the hood. Doing this got us mid 30s at the center vents on max.

Everything I read about a/c overhaul on the Net said r134a systems are finicky about the amount of oil to refrigerant ratio. A little too much oil yields poor cooling performance. If there is residual old oil remaining in the system, obviously one doesn't know how much to add the get the right amount for peak cooling performance and compressor protection.

RTorrez1

I sure can. I'm about an hour south of Corpus near Kingsville.

Turbo X_J

Drawing a vacuum on the A/C system removes (boils) the moisture out of it, not really "air".

mikesignal

what pag oil should I use? the sticker says nd-8, does anyone know the equivalent? I found a chart and it looks like pag-46, but then I read that pag-100 should be used but I just want to be sure.

I also read on the evaporator installation directions that 2oz of pag oil should be added to the new one. Do I pour the 2oz directly into the evaporator through either the inlet or outlet ports?

when i take off the compressor, I turn it upside down. I will catch the oil. Where will it pour out of? is there a cap or something that has to come off? I am also assuming I will pour the correct amount back into where the oil came out of.

thanks

djb383

When we did our overhaul, we poured 1/2 of the new oil into the accumulator and the other 1/2 into the compressor. Probably doesn't really matter where the oil is poured.....it's how much total oil is being circulated throughout the system. IIRC, we used PAG 100 and it has worked fine for 3 years now (knock on wood).

mikesignal

ok--I got pag 100. thanks for the info

one more question. I got a new accumulator a few months ago, but I have had it unhooked (open) for 5 days. Did I ruin it?

mikesignal

I just took the compressor off. On the bottom of the compressor it says to use pag 46. should I use the 46?

mikesignal

thanks for everyone's help with this. I got everything in and got it vacuumed and filled. With an outside temp of 75 degrees, it was reading 60 on a thermometer in the vent at idle. I checked it this evening while driving with an outside temp of 68 the vent's were reading 48 degrees on a thermometer.