According to our information, there is no separate HEPA filter as an accessory for this product. The integrated filter is washable, but not a classic HEPA filter.
Unfortunately, I can't answer this question 100%. I only used the appliance for 2 years on really hot days without the heating function. To date, I have not had to top up the coolant.
The best thing to do is to contact our customer service directly at https://helpcenter.digitec.ch/hc/fr/requests/new. Your request can then be examined individually.