You can really trust these guys. When my furnace was acting up and OCCASIONALLY blowing cold air only my biggest fear was that someone would charge me for parts and service that I didn't really need. Kang (the technician) was very knowledgeable and tested my system thoroughly before determining it was a simple inexpensive fix. My furnace now works great. These guys are very honest and understand the importance of great customer service. They won't try to upsell you unnecessary parts and service.
These guy never cease to amaze me. They are so responsive and really know their stuff when it comes to furnace repairs and air conditioning. I first used their services 2 years ago when I needed to replace my Air Conditioner Unit for my house.