Just added a covered patio at my house which included a few electrical outlets and 2 ceiling fans. They drew power from an outlet inside my house. Directly outside the house from the inside outlet they installed a GFCI outlet and tan the power to the ceiling fans and 2 other electrical outlets on the patio.

So far I have only had the 2 ceiling fans on, nothing else plugged in. At first the GFCI would trip immediate when you turned on the fans. After tripping and resetting the outdoor GFCI outlet a few times the fans would stay on for 15-20 mins before tripping. Electrician came back out today and checked the wiring at the outlets and fans and said it was fine so he left. As soon as he left it tripped. I reset it and it tripped again immediately (fans were on). I reset again and called the electrician back and it has been on ever since - over an hour.

What could cause it to trip immediately sometimes and now not tripping for over an hour?

Thanks,

have him change out the gfci, sounds like it is going bad.
they can only trip a few times and they need to be replaced in my experience with them, mine at the lake go out about once a yr. from tripping too much from storms etc.

but was is puzzling is that it is on now for over an hour after tripping all day yesterday and this morning before he came out.

I concur.

yep, got me on that one. if it keeps working I guess go with it.

could it be the fans?

cycle them off and on a few times, let them run a few in between.

done that.

it just tripped again. going to test to see if it the gfci outlet by turning the fans off and plugging a few things into the outlet and see if that trips it. have two garage fans plugged into the gfci outlet now

Yep, I'd change the gfci and see if the problem persists

Bad GFCI or you’ve got a skinned wire somewhere.

Motors can cause funny stuff with a GFCI. The GFCI outlet doesn't trip on excessive current like a breaker, it trips on a current imbalance between hot and neutral. Plugging new loads into the circuit isn't going to help pinpoint the issue. It's either the GFCI outlet, the wiring at one of the fans or just electrical noise from the fan motors. Might also try one fan at a time and see if one tends to trip it.

Start by replacing GFCI, then go from there.
My garage GFCI gave me issues.

is there another gfci in the circuit?

no

that is what i ended up trying instead of plugging in something into the gfci outlet. have one fan going now and will leave for an hour or so then try the other one.