2 ton condensing unit w/ 3 ton evap 100 suction 175 discharge

If the compressor on this case does not start install a set of gauges on unit and make sure pressures for 404a are correct for your ambient temp. at 70F you should have around 155psi on suction and discharge. if pressures are good and no power from relay on emerson board then remove bottom shelves from unit exposing evap fan/txv/coil. you will find a high pressure switch and a low pressure switch. cut wiring to both switchs and ohm them out to make sure they are closed. if one or more is open and your pressures are okay replace the switch. There are dilcores on switches so it can be done with out reclaiming if you are quick. if high pressure switch is faulty and does not open during hot pull downs the unit may trip on internal relief in compressor. 404a will run very high temp and pressure and may shut down up to 5/6 times on hps before unit suction and discharge come down. make sure condenser coil is very clean. wash with hot water and degresser if needed.
General maintence should be carried out on these units often such as cleaning the condenser. cleaning condenser pan and float check proper operation **** all dirt from pan and float with shop vac and wipe up all sluge from heater elements. remove bottom shelves to the evap area and vacuum any loose particals from inside and make sure drain is clear.
if you have product in case that is not keeping cool you may have to remove all shelves and remove back wall and vacuum dust from grates in back to get good air flow.