18"portable dishwasher
-power light on, dishwasher fills with water then does not engage in washing cycle. don’t think it is a problem with heating coil (water heat option turned off, hot water from tap). The only noise coming from machine sounds like right behind the knob timer (sort of soft ticking noise as if it is still going to rotate around)
what are common problems that I can try looking at ?
Here are your parts
Replacement parts for FRIGIDAIRE MDS251RER1 | AppliancePartsPros.com
Here is a tech sheet that includes a timing diagram
http://manuals.frigidaire.com/prodinfo_pdf/Kinston/154231901.pdf
Looks like if the timer motor is getting power it should rotate. The ticking noise sort of indicates that it is getting power but the gears are messed up so odds are high that the timer is shot. If the water valve float switch is turning the water off (float up, switch opened) and not the timer itself would also indicate a bad timer.
If you can manually rotate the dial and get the unit to wash and drain then perhaps this is all that is wrong.
If not then I would check the motor windings for continuity.
If OK
Then check the motor start relay.