Although I fly out later today, I'm still here now! However, Tatia's answer pretty much said a great deal.
This is an old, old question about the show and the lead characters--how did they get along? Many different tales of their initial arguments and how it was all settled abound. But, there seems to be no doubt that at first, Culp and Katt did not get along well, due to their different interpretations of their characters and how scenes should play out. One does wonder in all this where the directors, Cannell, and writers were who should have mostly been involved in those decisions, but then again, Culp no doubt needed to process all this on his own, as we'd believe.
After all, it's fairly obvious that Maxwell is a much more complicated and complex character than Katt's Ralph, and it was Maxwell who so wonderfully grew and changed during the show, while Ralph did not at all. Culp said that he wanted the show to do at last another season as he was "not quite done" with developing and solidifying Maxwell's personality. If only!!!
So, there was contention but then in one familiar story, we hear that about two weeks into the show the two men met in a trailer and got things settled down pretty well. So, even if they weren't best friends they were then civil and got along better. Culp, btw, got along fantastically with Connie Selleca, whom he really respected, and he appreciated her acting technique.