I understand your reasoning behind the individual slogans on each van, depending on their speciality but tbh I think you're only reducing your exposure and market by doing this.
For example I could be in need of my gardening doing desperately and your van could be parked a couple of doors away at a neighbours cleaning their carpets and oven in your "deep cleaning experts" van. I'm not even going to give your company a second thought as Im not psychic to know that you also do gardens and the two job types aren't exactly associated together. So I'll just walk back inside and ring a dedicated gardening company from phonebook/google.
IMO you need one slogan that sums up everything your company does so you can advertise to a maximum target audience at any one time, no matter which van it is.