Tenant agrees to allow Landlord timely access to premises to do maintenance and repair.Tenant will notify Landlord in a timely manner of any damages or problems as they arise, including damages caused by Tenant, malfunction of appliances or fixtures, and water/moisture leaks and spots.Tenant will take care of the premises, keeping them clean and clear of debris.

The only negative was that one of them had an issue with the motion detector malfunctioning after a few months.

To me, unless the tenant damaged it causing it to malfunction, you should simply pay it.

The units arent temperature controlled so no worries for malfunctions there.

We were amazed that a young couple we know just signed a similar rental agreement that stipulates that they are responsible for repairing/replacing any malfunctioning appliance. 

I repaired a malfunctioning garage door opener in one unit, ordered a replacement key-fob online, and gave it to the renter.  

I recognize that it can take some time to correct things, and then you have to do testing to evaluate whether anything else starts to malfunction due to a fix.

I'd like to have several inspections done (well testing, water conditioning system, hvac and garage door malfunction).

Should i leave the appliances and replace them as they start to malfunction throughout my stay? 

That being said it takes a specialist in most cases to determine what is needed for a slab on grade malfunction.