Rad fans not staying on..?

Had the motor out yesterday and when the rad fans click on they spin for 5 - 10 seconds then click off and keep doing that in stead of just staying on.

Figured a relay as 2 weeks ago the battery died and they worked fine before that happened.

Out else I could look at?

Is they any simple ways to check the relays to see if they are working?

Everything else works fine as far I can see and no raise in temp at any time (Didn't get struck in traffic and didn't leave it ticking over or anything thou)

If you've got the air con turned on they do that

Don't think I've ever had it turned on. Can remember testing it when I bought it and thats it. I'll double check thou, gonna have a look at it the mora