Home warranties are supplied by several companies. Seller's Agent usually assigns a home warranty company during the Buyer's escrow process. I suggest you do your homework as every company covers home repairs differently. There are also several tiers of a home warranty and it's cost to seller during escrow. Usually Selling agents take the less expensive plan for the buyer as it costs the seller less money. If during the home inspection you find out that the air conditioner has had some issues I would upgrade that home warranty to include air conditioners. The usual Home Warranty service contract covers:
Furnace Heating Ducts
Upgraded contract might include
Swimming Pool and Jacuzzi
Buyer beware that you need to find out what a home warranty covers before escrow closes.