The HOA will do whatever it is allowed under the CC&R's, any additional rules and regulations and the laws of the State of California. Some HOA's move quickly on enforcing collection and others don't. It really depends on the management company and the board of directors. You would be well advised to check with an attorney about your rights and obligations regarding your HOA (I am not an attorney and thie information I am sharing should not be relied on as legal advice, only my eperience from being involved in many shortsales).
Here are some of the things I have seen HOA's do when you default on your fees:
1. Take away your rights to use HOA facilities such as pool, clubhouse, etc.
2. Do not allow you to vote at HOA meetings.
3. Do not respond to your complaints about noise, bad sprinklers, etc.
4. Begin foreclosure to enforce their collection rights.
Again, depending on your HOA, you might consider calling them and letting them know that you are in the short sale process due to unforeseen hardship. Let them know where in the process you are (hopefully you have a good offer into the bank and things are proceeding smoothly towards sale, at which point in time the HOA will be paid current), and ask them for a forebearance against collection actions. I have found that, unless the HOA is extremely unreasonable (and only you would know that from prior experiences with them) when homeowners are forthcoming with information on their situation the HOA wants to help them out and in that way help themselves get paid sooner.
I am sorry to hear that you are having hard times right now. I am certain they are temporary and that this short sale will remove some of the stress and help you move on with your life. Dare to Dream.
Real Estate Consultant
RE/MAX Palos Verdes Realty