I bought Arctic Freeze R134 freon because it was real hot in New Jersey the other day. I filled it until it said full on the gauge, it was smack in the middle of the full part of the gauge. The A/C was not cold. Than I noticed the compressor was not cycling.. Than I jumped the low pressure switch, because that shuts compressor off when freon is low. The compressor was cycling on and off couldnt get a reading. So I took the jumper off and pluged it back into the low pressure switch. It was stillcycling but was able to get a reading it said full like it did in the begining. So I didnt know what to do so I added more freon the air started getting cold and the compressor didnt sound as stressed. So what could have gave me that false full reading or could something be stopping the compressor from working than when I jumped it it fixed it?

 

When was the last time AC had full service, i.e. new receiver/dryer and orifice tube replaced?

Low side needs a minimum pressure so compressor doesn't burn itself out trying to suck in fluid that isn't there

Orifice tube(aka Expansion valve) is a filter with small hole that allows high pressure side fluid to slowly expand out on the low pressure side, this provides the cooling effect
If it was blocked then no fluid was flowing to low side until compressor came on and pressure got high enough to push the blockage out

So probably time for a full service

 

I had the truck 8-9 years. The first two years I didnt have to do anything with the A/C, it was ice cold. It looks like a new dryer on it too. So I d say for the last seven years I go to the auto part store and get a can of R134, and its ice cold until the next year. This is the first time I added R134 and the compressor did not kick on. The compressor would not go on until I jumped the low pressur side, but it was going on, off,on, off. The gauge was doing the same thing pressure up pressure down ect. So I took jumper off and plugged it back in compressor stayed on but stress sounding. So I added more R134 it started sounding better than the pressure dropped added more I guess the high side was dragging it over. Can it be just a bad gauge or was it a blockage that cleared itself? I went to Harbor Freight and bought the gauges it was on clearance for about $40.00 Happy Memorial Day!!!