I have 3 year old Carrier 24ABR that I have used no more than 6 times. This year, when I turned it on, the exterior unit turned on (fan was spinning) but stopped about 2 seconds later. If I override the thermastat (according to the directions), I can get it to start again but it immediately stops. Any ideas?

Thanks

Thanks in advance but I have solved the problem. I changed out the thermastat and it is now working. Cheap fix so I am very happy.