My MacBook Pro 2014 keeps flickering when I plug in a HDMI to VGA converter to it. I am using HDMI to plug in the HDMI to VGA converter (which is plugged in to my monitor). The screen is just black and then the Mac starts flashing. The external monitor does not have any effect. I tried out the wiring and monitor on another windows computer and it worked smoothly.
The MacBook Pro's HDMI port has a DVI-D implementation. This means it has no analog signal, which is what VGA relies on to connect. More information here: apple support forums . Apple supplies an HDMI to DVI adapter, which could solve your problem if your monitor has a DVI port. If not, then I would suggest getting a Thunderbolt (Mini DisplayPort) to VGA cable, then using the Thunderbolt port on your Mac to link to your monitor instead.