So I have a customer who has a york RTU that is only 3 yaers old 410A. I got a call middle of July No cooling Found the compressor not compressing. Got new compressor under warranty pulled charge changed compressor with proper procedure.(flowed nitro etc) The unit ran fine for 3 weeks get a call not cooling again. Go out thier find it tripped on high head preasure. I jumper out the HPS and the RTU climbed to 800PSI and the obstruction cleared. I stayed and cycled the unit and took readings and everything is A1. So today I go by to do maintence and I find the unit tripped on High preasure again. I do the same thing and it clears and unit is running fine. I have pulled every panel off the unit I can not see an obstruction in the system. It is not a TXV its just a metering device that you canot pull apart. None of the lines are frosting. It all looks ok.
So what do you techs think? Something is causing an obstruction when the units off?
To much oil in the system causing High preasures?
What do my Fellow Techs think?