Auto Air Conditioning & Heater Repair: 1998 Dodge Dakota Blows Warm air, freon 134a, vaccum pump

Question

For a friend...
5.2L 1998 Dodge Dakota. System has slow leak( holds for more than a week). System can be charged and works fine for a bit. Dye test shows no leaks anywhere. when system died, my friend added red devil selant and work fine for 2 days. it blew very cold and then died.the system has freon 134a and when the low pressure switch is cheated, the compressor locked but still blew warm air( freon level is ok)
Since the dye test did not reveal anything, We decided to replace the accumulator/dryer/ evaporator and added an orifice filter ( there was none in system where the lines connect from the dryer to the condensor but worked without it??). Anyway if the system was opened and 2 lbs was added to the system with 6 0z of oil. Why doesn't the system work. What else can we check or try. Can a compressor fail with no noise and still engages when the low sensor switch is cheated?? We disconnected the line from the compressor to the dryer and was full of pressure ( I assume the compressor works??)What are your thoughts?? Does this need a vacuum first??

Thanks

Chuck in Atlanta,  

Answer
Hi Chuck,Had the experience of dealing with freon sealant and it does plug up everything. It will plug up the block expansion valve and completely cut off the flow of freon.
Are you using service gauges and a vaccum pump?It also sounds like the compressor may be defective.The whole system needs to be flushed with a/c solvent.I hate to say it but you might have to start all over again.You have to evcuate with a vaccum pump for 45min. before charging.Doesn`t sound like it was done in your story?

Good luck,davidt