I have had two buses with OTR and Cruise Airs. I have had the OTR quit for the same reason Deb and Eric's quit and that was a failed circuit breaker. But when it quit it was a day in the 90's and I found out that when heat radiates off of a heat soaked highway the cooling air available to the Cruise Air condensing units is insufficient to keep them operating and they shut down. If the coach had roof airs it would have been picking up clean air high off the highway that was not being heated from the highway.

Cruise Airs however have their place and when parked (or modified as described below) they work great because the ground beneath the bus is shaded so there is air capable of cooling the condenser effectively. Their benefit is they are relatively quiet and they are not built to be replaced so they tend to be reliable and have a longer life than the typical roof air. Some owners have made modifications to get good performance from Cruise airs. I know of one coach that has an improved condenser fan system to jam more cooling air across the condenser. I know of one that has had a pressure switch installed and that switch controls mister sprays when internal pressures creep up keeping the units functioning. So the short answer is Cruise Airs are not the best thing if you need to fall back on them. Having said that I had a relay quit on my current coach last summer and I needed to run the Cruise Airs. I was surprised when they worked very well despite high ambient temperatures and did not shut off like my Cruise Airs did in my first coach. So maybe those that do fail to function are either in excessively hot temps or something has changed.

I don't know of anyone whose roof airs shut down when the highway temps are excessive.