It seems like the drian valve is stuck open on Hoover 500M afetr the first wash cycle and wont fill up to rinse. Is there are part that has broken and can I buy one to fix it?

The dispensers are flushed during the wash cycle. Part of normal operation

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first check the water is switched on to the machine. If it is then you most likely have a faulty water valve. Switch all power off and remove the top panel should be 4 screws or so. If it has 1 valve then replace it.

Clogged screen in fill valve on cold side. Remove hose from cold side on valve. Pull screen out. Wash under hot water, and re-install.

Yes it is not measuring the water level or the valve is stuck. If it fills ok on the wash but not the rinse it must be one of the inlet valves. Identify which valve is for the rinse and check if it stuck open. If it is repalce it. The valves are at the end of the fill hoses. Hoe you have success. Thanks Tony

Rinse cycles are normally with cold water only.

I believe you have a faulty cold water inlet valve. To confirm, put the machine on a cold only wash cycle, and see if it fill up with water.

If it does, then the valve is O.K. In that case the problem you are having with the rinse cycle is most likely a timmer fault.

Good Luck
Ash

The problem you are having could simply be the inlet valve.

The inlet hose is attached to the inlet valve on the machine. Where it screws on that is.

You can get a valve from an appliance parts shop and they are inexpensive.

if the water continues to fill even with power off, and you have to manually shut in off at the wall valve, the 3-way inlet valve is stuck open. you have to replace it. $90

An HF Code is a Water Inlet Problem- No or Insufficient Water Supply.

Press Pause/Cancel twice to cancel the cycle. Then, unplug the washer.

Run down the list again:
Make sure faucets are completely turned on.
Make sure the fill vavles (screens where water enter machine) aren't clogged.
Make sure the hoses aren't kinked, etc.

Plug the machine back in. Try another cycle. If the problem still occurs, You may need to replace your Water Fill Valve. Let me know if you need any further assistance.

Probably very repairable but impossible to say how much without looking inside and fiddling around and checking a few things.
Fault could be caused by several possible faults at widely varying cost.

I suggest you call a friendly local white appliance engineer...