Do you really need to take the top cover off or just need access to the wiring/control panel? If the latter is the case, first switch off the power to the unit, then remove the front panel using a flat heqad screw driver to turn the fasteners a quarter turn counter clockwise. Looking inside and up you should see two silver hexagonal screws with a phillips head slot. Remove these two screws and then slide the panel down to access the wiring/control panels. If you still need to get the top cover off. Look agian inside and you will see a further two hexagonal screws. But you shouldn't really need to take this off as most of what you're looking for will be in the wiring/control panel
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Do you really need to take the top cover off or just need access to the wiring/control panel? If the latter is the case, first switch off the power to the unit, then remove the front panel using a flat heqad screw driver to turn the fasteners a quarter turn counter clockwise. Looking inside and up you should see two silver hexagonal screws with a phillips head slot. Remove these two screws and then slide the panel down to access the wiring/control panels. If you still need to get the top cover off. Look agian inside and you will see a further two hexagonal screws. But you shouldn't really need to take this off as most of what you're looking for will be in the wiring/control panel