I know this post is a month old but just in case you haven't gotten the info as of yet..
, that is where I found out which 'cold control' that I needed. they also have a list of places that carry their parts. Dave with Comfort Air 616 454 2200 is a distributor for Tempcon. He is a lot higher in price than others but at least he would have it.
I also found some a/c parts on www.jcwhitney.com
but you would need to put the year and make of your chassis in where they ask for the year and model of your vehicle in order to get the right items to come up.