Hi, we are trying to control the compressor of a ref.

We used an H-Bridge circuit to control it. Our aim is basically an "Inverter Circuit"

http://images.elektroda.net/42_1308180076.jpg

we just used the "resistor" as a motor for representation

we have a 315VDC rail, and we are just varying the switching speed of the transistors using our PWM microcontroller.

Do you have any idea as to why there is a continuous clicking/ticking sound?

We believe that the sound might be coming from the relay of the compressor.. but we are not really sure.

The refrigerator is only a small one, about 2 or 3 cubic feet
The compressors also does not run since it is not getting cold inside the refrigerator.
Your help will be very much appreciated, thank you!

an additional question. What would happen if remove the connection in the start PIN and just directly connected the supply voltage on the RUN and COMMON pins of the compressor?