I recently prepared a pork roast, but it wasn't ready in time for supper. Once it was fully cooked, I switched it over to "warm" for the night to be ready for today. But now I'm a little worried if it is still good. I have heard that as long as the "warm" setting maintains a heat above 140f it should be fine, but I do not have a functioning thermometer to test this. If someone else has a PC550 slow cooker, and can give me a reference of the (approximate) setting (warm, 1, 2, 3) temperatures, that would help!
so I am wondering what I should do from here (turn up the temperature, refrigerate it, etc.).
Raher late advice given your posting date, but perhaps helpful if you still have and use the PC550.
As long as temperature is over 63C chill quickly. For instance put in small containers and then put them in cold water. Then refrigerate or freeze. And before use reheat thoroughly; preferably on a stove top rather than in a slow cooker.
Note if the warm temperature is not holding at 63 or above the food is not safe to eat, but surely a slow cooker on warm will be designed to hold warm at above 63. I do not have this model of slow cooker, and did not find the manual for PC550 on the internet.
I did note a post regarding a Presidents Choice slow cooker pointing out it automatically turns off after keeping warm for 6 hours, although the post did not specify the model of PC slowcooker. You may therefore need to check it is still keeping warm. And as advised by @rackandboneman you really would benefit from having and using a food thermometer.
Note advice is usually that food may be held indefinitely in a slow cooker if over 63 degrees C or as in this USA advice over 140F (that is 60C) https://www.foodsafety.gov/keep-food-safe/4-steps-to-food-safety