My Casita TT had a Coleman A/C that had a Heat Strip. There was an OEM safety switch that would trip if things got too hot (normal operation does not get too hot). I initially was NOT aware that, after using the Heat Strip, it was MANDATORY, AFTER switching the Heat Strip off, you had switch over to blow cool air for a couple of minutes (rather than just switch off the unit). I did not do this and, the NON-SELF-RESETTING safety switch tripped (ie: it did its' job). It was necessary to partially disassemble the interior of the A/C cowling to gain access to said NON-SELF -RESETTING safety switch. There IS a SELF-resetting safety switch you can buy. I located and installed one and never had problems again. Of course, after disassembly and manually resetting the safety switch, you could just reassemble everything as long as you were careful enough to NOT let an overheat condition occur again. I opted to upgrade the switch. I suspect that this design is mandated by some government agency to save us from ourselves.