What to do? Gas/diesel

Ended up pulling the trigger on the Damon Intruder. Find out it's a 2000 model not a 1999, not that that makes a difference but it's a pretty nice home. Couple issues I'm having with it right now are the leveling jacks won't come down. The green light is on but as soon as I release the levers nothing happens. Checked power to the pump and have good power there. I'm thinking it's some sort of safety thing that I'm not doing right. I have the parking brake in and the gear shift selector in park but still nothing happens. They are the HWH manual jacks. Also the heater A/C blower for the engine heat only works on high. I've changed out the relay and resistor for it and still the same. Actually if I change out the relay for the new one I get nothing so I put the old relay back in. I'm lost and don't know what else to do other than getting a new heater control unit. Any ideas from you guys on this? Other than that everything seems to work and the inside is in near perfect condition and I love the floor plan. Just need help with the jacks and blower motor. The previous owner said the jacks were working earlier.. What am I doing wrong or what switch is not working and not allowing them to extend?? Thanks for any info..