I'm working on a two year old GREE GMV 60 VRF with two cassettes that is intermittently locking out on error code E2. When i arrive on site and reset it, the system runs normally for the whole time i'm there. Has anyone dealt with this ? It does seem to trip more readily with peak summer temps lately. The tech support has been struggling with this one. On the GMV models the E2 error indicates compressor discharge low temp protection and advises to check the discharge temps and sensor ohms. Measuring with a meter the discharge pipe temp sounds low at 60 C but there is another identical system beside it that has roughly the same discharge temps and hasn't had the E2 code. The manual for GMV60 recommends to check the discharge temp sensor ohms and temps and replace the main board if the sensor is ok. A co-worker already spent a bunch of time on it and replaced the discharge temp sensor which came as a harness so a bunch of other sensors were replaced as well. The ohms were fine on the original sensor anyways. The tech support then recommended removing refrigerant charge since the charge adder for line set was supposedly too much. It has 14.3 lbs pre-charged and installer added 4. Co worker removed 2 lbs and it later still tripped on E2. i pulled another 1/2 lb and it still eventually tripped. i recovered and weighed the charge to be sure. Seems odd that an overcharge can cause this. and i dont' see it being overcharged when original charge adder only added 4 lbs... the line set still has some length to it like probably at least 30 and 45 feet to the two cassettes. Pressures seem ok with suction at 120 and high side slightly over 300 on a mid 70's F ambient day. I noticed on the the GMV72 which looks identical with its hardware and controls , the manual is more detailed and has different recommendations of checking the outdoor unit sub cooling expansion valve and indoor unit expansion valves as well.(the GMV-50 also has these). and to check for contaminated refrigerant. Researching online I found nothing... only one video on you tube addressing the E2 error on a GMV5 and it's showing techs in the Philippines who don't seem to do much other than check some wiring connections... but hard to say because i don't speak Tagalog.