@Jeff Cliff -  You can still test the lines for leaks by pressurizing it with an air compressor. 

Quote from @Hector Serna: Quote from @Max Feinberg: @Hector Serna sounds like some of these things could be resolved/noticed before actually getting under contract  Looking for adviceThank you though For properties where the utilities are off, this can help you discover potential plumbing issues:At the home improvement stores, you should be able to find the fittings to make an adapter for connecting an air pressure tank or portable compressor to a hose bibb.

If I can give them $250 to leave, and this is an insurance policy, and in the process it ensures I won't face $5,000 worth of drywall damage, a stolen oven, AC compressor, etc etc....then how is it NOT worth it to give them cash for keys?

Its 18 years old and wasnt used much but the compressor isnt working anymore.

I would use the resources like yellowpages, google reviews, ask at a real estate investor meeting or maybe sign up for Angie's list and find the best HVAC company and installer who, stands behind the product, is willing to educate you on the right equipment and provide you a fair quote.Your investment strategy, and what the standard is in your area will dictate the price.I would look for the Highest seer, with a good warranty 10 compressor, 10 year parts, look for one with quiet technology (compressor sound blanket, motor mounts, Air handler blower motor, air flow designed for quietness) and ease of service for the air filter, air handler coil cleaning, overflow float switch, and access or instruction on drip pan tablets/liquid and drain line cleaning.What I look for in a HVAC installer is someone who is proficient and not on the phone or looking through the manual a lot.  

Things like refrigerator compressors going bad (often from running too much because of dirty coils) and similar are too hard to prove, so you just consider it a cost of doing business. 

Disposal was working fine prior to move in.AC repair from them trying cool house too fast and cause the compressor to break and need replacement.

A pressure test using a air compressor could have detected the broken pipes.

All units should have overheating protection built into or part of the unit setup, wherein it simply delays the operation of the unit until it is safe for the unit to operate, and shuts it down as necessary in order to prevent damage to the compressor.

Ive seen many compressors fail at four to five years.