I think the clearance requirements differ by type of refrigerator.
Here's what works if your refrigerator does not have cooling fans and fins in the bottom of the refrigerator.
This is the Haier refrigerator I installed in our motorhome.
This refrigerator has no cooling fans, so it needs air intake at the bottom, and air flow upward along the back of the unit. I have very little clearance on the sides and the unit works great.
Refrigerators with cooling fans in the bottom would probably have very different clearance requirements.
I had space above the furnace (below the refrigerator) so I drilled several 3/4 inch holes for air flow. There is a 3/4 inch gap above the refrigerator, and I do get a flow of hot air out of that top gap when the refrigerator is running. That hot air goes back inside the coach. Since the refrigerator does not cycle on very often, the heat input to the coach is very small.
I closed off the ceiling vent. I also blocked the removable outside refrigerator vent by using some foam board so that I could still remove it from outside (to get to the 110 volt plug and/or bolts if I ever have to remove it).
Fred
