I am not a big fan of dumping hot water into a HP condenser unless a snow/ice storm completely overwhelmed the condenser and the defrost function failed to do its job. Yes, it happens. Those nice Trane XLi tops prevent that from happening. If the source of the noise can not be identified, I would shut condenser down and assuming this is a HP, I would switch over to emergency heat and call your HVAC dealer for service.

IMO

Assuming the snowstorm has passed, yes, I would clear off any old snow/ice. Hot water should do the trick now provided that it won't freeze as soon as you stop. Turn the unit off while you do this. After you have cleaned out the condenser, keep an eye on it to make sure the defrost function is working as it should. If this happens again, then you should probably get a pro out to check it over.