I have a '93 Cadillac Sedan Deville and I want to recharge the a/c system with the R-134 freon. The car has an electronically controlled ventilation system which disables the a/c function from turning on if there's not enough freon in the system. Will I need some special equipment to make the computer turn on the a/c function so I can recharge the system?

Thanks for any assistance.

im having the same prob on my 89. tried to keep turning the air back on but it kicks out before you can do anything

You have to start pressurizing the system before the ac clutch will engage. There is some information about this topic in this forum already just do a search on "r12 r134a" and you should find them.

find low pressure switch . place a jumper wire across it .then run ac while charging,turn 134a can upside down to hurry up and get liquid into system,then turn right side udp for gas to finish it up.

You shouldn't need to jump the low-pressure switch. The pressure in the can is plenty to close the switch. Hook the can up , open it, turn it upside down, and turn on the A/C system to the highest setting (but not recirc). The compressor should kick on. It is normal for it to cycle.

I filled my '01 DTS from empty this way. No jumping of switches.

Jim

the 93 may be a bit diff tan the 01.

First off, the '93 has R12. Don't use R134a unless it has been converted.

If the compressor has been disabled because of low pressure, have the can hooked up and ready to recharge like TurboJimmy said (upside down so it fills quickly as a liquid). Clear the codes that disabled the compressor through the DIC or by pulling battery power. Then start the car and turn the A/C on max cool and the refrigerant should be pulled in before the low pressure switch trips again. Have someone hold the can for you while you start the car and turn the A/C on.

the 93 may be a bit diff tan the 01.

Maybe, but my '87 worked the same way. It's just a pressure switch common on all systems. When you pressurize the system with the can, it should close.

Jim

Draw a vaccum in the system and it should take in at least 1 can before you have to start the engine or compressor.
Mine is an 89. Did not have to jump any switches.

how would i draw that vaccum then

With an A/C vacuum pump. If you don't have one you'll have to take it to an A/C shop.

Maby some small indipendant garage will do the vaccum for you pretty cheep.
If you are going to change it over to 134 you can get the fittings, a 2oz. can of oil
and 3 12oz cans or 134 for around $30.

Hook up your freon to the connection. Unhook the negative battery cable and wait thirty seconds. Then hook it back up. Start the car and turn on the ac to Auto and 60 degrees and then hurry up and start putting the freon in, before the computer shuts it down again. This is the way my 93 was

Blaze

I have a similiar problem with my '95 eldo - very low refrigerant: A/C Compressor Off. However, I had a buddy mechanic look at the car and he put in two cans of refrigerant, but the system still said the same thing. I read the part in this thread to disconnect the negative for 30 seconds. Did that and now I can hit the "Auto" button without it immediately going to ECON. However, no air is coming out of the vents - I noticed a crack towards the front of the engine compartment, but I have no idea what is cracked - also, air comes out of the vents once I start moving, but not very much. I think outside air is going in the crack and forcing itself through the vents.

Any thoughts why the fans are no longer blowing?

Here are pictures to explain what is cracked. The first picture indicates the area of the engine compartment I am talking about - the crack is behind the black bar. The second picture shows the crack just above the spark plugs
http://imagehost.biz/ims/pictes/324676.jpg
http://imagehost.biz/ims/pictes/324674.jpg

Thanks to some aid in one of the replies to my post, I finally found out that I was supposed to disconnect the negative post from the battery for at least 5 seconds then reconnect it, start the motor, then quickly connect the freon to the low pressure port and charge the system. I did all this and it appears to be a success because after charging it with just 2 cans, the a/c was blowing out some pretty cool air inside.

So I just want to appreciate everybody who took time out to help me find out what I needed to do to charge my car's a/c system. Thank you all!