My ac is not blowing cold air already check low pressure side its about 70 psi won't take anymore 134A compressor is coming on for about 3 sec then off for 1 min ??

 

Mine will blow cold, then it gets hot and you have to lay on the pedal for a few seconds to get it cold again. We have changed the high pressure and low pressure switches and added more freon. Not sure what else to do at this point. Anyone have any ideas?

 

It's important to know the year and model of the vehicle.
Do you have any A/C manifold gauges to use to check the system pressures?

 

Try recharging the AC you can buybthe kits from any parts store

 

I am having a very similar problem. Truck is a 2000 F-250 Diesel. Last summer it started to have a problem with the A/C going off and on (the compressor I think). When it is on the unit seems to cool OK. Has gotten worse this summer. I would like to know what the problem most likely is and how many dollars it will take to fix it (approx) ?

 

A/C systems are not supposed to leak out refrigerant, but some do !
Many times all that is required when the system keeps cycling very fast is, to carefully and correctly add some refrigerant to the low side of the system. The rules state that all systems that have any kind of refrigerant leak should be repaired first before adding refrigerant. Sometimes the leak is so small it costs more to repair it than just add some refrigerant. That may be all that is required to solve the cooling problem.

 

** Dan Bortolotto ** "check low pressure side its about 70 psi "

Are you getting that reading with the engine OFF and everything at ambient temperature? Or is it when the engine is running and the A/C ON.

What is your ambient temperature since the "SLEEPING" pressure will change depending on the ambient temperature.

With the A/C on MAX and the engine at 1500 RPMs, normal operating pressures normally range between 30-45 PSI on the LOW side and 200-250 PSI on the HIGH side. These pressures will also vary depending on the ambient temperature.