Your questions answered: HVAC FAQs. Alan Heating Air Conditioning, Inc. in Elmhurst can answer all your HVAC-related questions. Before you get on the phone, check to see if we already responded to your question online. If you don’t see your question listed or want more information on a particular topic, give us a call at 630-833-1100. Our staff can provide the information you’re looking for in no time.