Air Conditioning Help

So its summer now & the air isnt working in my jeep or my truck or my house, hah anyway. I went to the store to get a a/c recharge kit in hopes of getting one of the vehicles charged up. I understand how to add the refridgerant to the system, but when I hook up to the low side port air or whatever comes hissing out so that I cant add anything to it.
I assume I need to evacuate the system of this air? What is the proper method to do so? Do I need a vaccum pump to get everything out, because I assume I cant just leak it into the air?

just take it to a local shop there is a lot more then just recharging the a/c and if you try to put more in the system then what its designed to hold you will blow out o rings and have no a/c a shop will recover all the r134 add some dye to trace leaks and fill it to the proper level if that's all it needs assuming that the compressor is functioning properly and the receiver /dryer has not failed or clogged

Yeah yeah, anyway that tells me nada that I didnt already know. I am more interested in why air is hissing out when I connect to the low side port.

MrShaft696 said:

Yeah yeah, anyway that tells me nada that I didnt already know. I am more interested in why air is hissing out when I connect to the low side port.

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That is probably not air hissing out, It's likely R134A.

garr said:

That is probably not air hissing out, It's likely R134A.

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Well should I sniff it out of the system?

MrShaft696 said:

Well should I sniff it out of the system?

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Are you connecting up the hose with the Vehicle running & the A/C on High?
If yes then the can of R134a should go right in. If it does not go in then you have other problems with the system.

Are you opening the valve on the compressor about one to two turns clockwise? (I believe the '96 has the same valve setup as earlier models.)

Pelican said:

Are you opening the valve on the compressor about one to two turns clockwise? (I believe the '96 has the same valve setup as earlier models.)

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no I didnt read or hear anything about doing that to recharge the system?

Somebody please correct me if the '96 has a different valve setup. In the meantime, it is easy enough to check. Look at the charging ports and see if a valve stem sticks out at right angles to each of them. It should have black plastic cap. I usually end up using vice-grips to turn this after removing the cap but pliers or a small end wrench will sometimes do. After attaching the charging quick-disconnect fitting, turn the valve stem clockwise just enough (about a turn and a half) to open the port -- the can will get cold when it opens and refrigerant starts to flow. Opening the valve too far will result in re-closing the system at the other extreme of it's travel. Close the valve counter-clockwise after charging and before removing the hose.

Note that regardless of whether the valve is closed, attaching the charging hose with the proper fitting to the proper low side charging port should not result in a release of 134a or anything else.

Again, I do not personally know if the '96 has the valve, but if something starts leaking when you attach to the quick-connect fitting, you have some problem with the mechanics of the charging setup.

ok ill check that out, maybe take a pic when I get home.

1995 and higher have different hose layout and different fittings (they connect into the back instead of from the side, and the service blocks are gone). I've looked at the different years because I wanted to reroute the low pressure line on my 91 away from the fender (where it loops behind the PDC) and looked at the 95 and 96 hoses being unusable because of the angles and fittings. The EPA mandate went into effect in 1995 so that is when everybody made the hard changes, my poor neighbor with his 93 Caprice has SAE fittings but the 95 are metric!

Well I was able to do a successful recharge in my toyota truck last night, but I went to go work on the jeep and now the compressor wont even come on. It was coming on all the time before even though it was just blowing hot air, so I dont think its a smart idea to try and add anything to the system. I heard this may because of a pressure switch and it thinks there isnt enough pressure in the system to turn the compressor on>?

There are a few reasons why the compressor won't engage but low refrigerant is certainly the most common. There should be a two-wire plug on the drier, that's the pressure switch. With the AC on MAX, pull the plug off the switch and use a small wire to jumper the pins on the plug. If the compressor engages when the switch is bypassed then yeah you're low on refrigerant.