Paul
The information on your post above is a little confusing. If the carpet's fibre is polypropylene, the dye
WILL NOT bleed as the yarn wasn't dyed in the first place. It's more likely that the fibre is polyamide (nylon) or, most unlikely, polyester or acrylic. Do your tests so that you know what you're working with.
Elevated water temperature is more likely to set most stains, so this should be avoided. There are also the usual risk elements of elevated temperatures, including a greater risk of dye bleed, especially as the pH could be raised 5 fold at elevated temperatures (0.5pH) Have you tested with an acidic rinse? Or neutral detergent? The maximum temperature I would use would be 55 to 60C, but test everything to be safe. When I attended a Prochem course many, many years ago, we were shown a sample of plain coloured carpet where the dye bled, leaving a white carpet
If Sir/Madam has a spare offcut, use that to carry out your tests.
Safe and happy cleaning:)
Ken