Fisher and Paykel dishdrawer top drawer won't fill

SOURCE: Top drawer Fisher & Paykel Dishdrawer no lights lcd

Your original problem, F4, was the machine trying to tell you that the heater plate was not working. When you turned the drawer up-side down, you may have damaged the wiring harness. If you do get a technician, call a fisher paykel authorized servicer, not an independent, and make sure you tell him about the F4 problem. A new problem has been introduced by the cleaning procedure, and both issues will need to be resolved.

SOURCE: blocked drainage hose in Fisher and Paykel top dishdrawer DD603

Hello there..
How do you know the hose is blocked at all? It's rare for that to happen, I work on these machines daily as I am a Factory Authorized tech. You need to be careful in your approach to this, that is an expensive machine and it can be damaged by improper service procedures.
For starters, there is a flap valve on the end of the drain hose that would prevent you from introducing any sort of pressure backwards into the machine via the drain hose. For example, if you took and tried to blow air thru the drain hose outlet end, you would force that flap closed and create pressure in the hose. Also putting caustic drain cleaning substances is very, very bad for your machine and can cause some serious damage.

I will be happy to try to assist you, but let's start at the begining, shall we? What prompted you to conclude that the drain hose is 90% blocked? The first thing you should do is take out the rack, wash arm and tha large stainless steel filter plate. Next, pull the rotor up and out of the pump base (none of these procedures require tools) and make sure the grey impeller is not "freewheeling" or has become detached from the rotor shaft. The blue wash impeller on the top and the grey drain impeller on the bottom must be "one to one" meaning they are firmly connected to the shaft of the motor and turn together.
Next, check the tube or passageway in the drawer between the sump (where that small removeable filter screen is) and the pump's sump area (where you pulled up the rotor)
If you have any blockage, it will be in that tube.

There is some glitch here where I do not get notified of response to questions, so I will check back to this post.

SOURCE: u3 code on fisher paykel dishdrawer how to reset?

This site tells you how to reset:
http://applianceguru.com/forum1/163.html

I have the same issue and will try this tonight to see if it helps.

SOURCE: current service manual for the Fisher & Paykel DD603SS dishdrawer

http://www.fisherpaykel.com/admin/pdfs/pdf_usecares/527971B_DD_user_guide_USw.pdf

SOURCE: I have a Fisher Paykel dishwasher with water in top drawer

You need a Air gap kit designed by Fisher and Paykel to address this problem. It is pricey but it is worthy. I used this and very happy with it since no back flow problem from one while other running. Here is a link to order it.http://www.fisherpaykelparts.net/product/WT50/WT50-Dual-Air-Gap-Kit/