Shift 3 projection alarm clock cannot connect with the remote

I expect that since the unit reads the outside temperature from the remote thermostat, there is no need to "reset" the displayed number since this data is obtained live from the thermostat.

Is the remote very far from the clock? I find that some of these remotes don't have very good range. Try bringing the remote close to the clock to see if you can get them to connect. Some of these type remotes have a reset button or an opening that you can push a paper clip into to reset. I usually try to find a location close enough to the unit so it will connect by still try to keep it out of the weather. I also included a link to the instructions:
http://www.hmdxaudio.com/media/documents/hmdxaudio/instructionbooks/HX-B320_EN_IB.pdf

I don't have this particular unit, but with the one I have, you have to power up the main unit last to get it to sync with the external unit.

Make sure the out door sensor has fresh batteries, and that the clock inside is close to the location of the sensor outside so they can connect. If none of that works, time to replace the unit.....

No solution but to return it...very annoying product but yet I like the projected display, very sharp and bright. The replacement was much better, it loses connection with outside transmitter often..but occasionally we see the outside temp

1) Does the remote have batteries? See other posts that describe how to do this (4 screws in back need to be removed). Temperature should be displayed in small window of the sending unit if it's working.
2) Hold Channel button for 3 seconds until it beeps - the unit then searches for a signal.

If you have storm windows, put it between the window and the storm window.

Or try just below the overhang of your house.

go here and look for your model
http://www.lacrossetechnology.com/support/manuals.php

Once the batteries are installed in the remote the temp will appear in the LED screen. Now you are ready to link signals between the main unit and the remote. Simply remove one of the two triple A batteries from the main unit and then replace. You should then see what appears to be a flashing object shaped like a kite with a tail while the two units link up. Then you should see the temp reading at the remote appear in the LED readout at the main unit. By the way there is also a very small reset at the top of the switches on the back of the main unit that can be depressed with a SMALL pointed object like a scissor point or safety pin point.