What activates the contactor relay on a central air unit.

Will a 30amp 2-pole contact relay work in the place of a 25 amp 1-pole contact relay? Both have 24 volt coils.

My unit had the main circuit panel replaced 2 weeks ago. (2nd time in 5 years). Not sure why keeps going out, but we have a lot of power surges and lightening problems here. Anyway, now, the contactor which engages the compressor outside won't stay in so that the compressor will kick on unless the...

My outside heating/air unit will not turn on . I opened the panel and if I push this little spring loaded thing it contacts with a small circular object and the unit kicks on, when I release it turns off. It's a brand new unit, about 5 or 6 months old. Can I fix the problem myself. Repair guy can't...