a/c help

[ampman_27]

I tried charging my a/c the other day on my 1994 4.0 and the compressor will turn on for a second or two draw down to about 25 or so and then kick of then pressure will build back up and it will turn on again, and yes I am trying to charge it from the low side. Anyone have any ideas why this is happening.

 

[TomJenks]

I tried charging my a/c the other day on my 1994 4.0 and the compressor will turn on for a second or two draw down to about 25 or so and then kick of then pressure will build back up and it will turn on again, and yes I am trying to charge it from the low side. Anyone have any ideas why this is happening.

It sounds like you're hitting the low pressure switch. Was that reading on the high or low side of the manifold? What is the temp. like when you were trying to charge it? If its not warm enough outside the pressure will read too low and in turn not let the compressor cycle for any length of time. What kind of readings are you getting on your gauge set? If it is fairly warm outside, then I would suspect the low pres. switch is bad.

 

[kimcrwbr1]

put your charging can in a pan of better than warm water to warm if up and turn it upside down to add the liquid then start the engine and turn it up right and add it as a vapor when the compressor is running it might take a while but you need to get the pressure in the system up for the compressor to pull the vapor from the can. refrigerant has the same pressure and temp weather there is 1 oz or 1 lb so warming the charging can up will make it higher than the system pressure do not use any flame to heat the can a hot water bath around 95 degrees will work just fine to increase the pressure in the can above the system pressure.