TWO-SPEED COMPRESSORS HARD START FAILURES?
 
Q: What can be done to help cut down on two-speed compressor hard start failures, granted voltage and a proper Carrier® two-stage Thermidistat™ control are used?
— Karl W. Wendel, Parts Manager, Purchasing Agent and Safety Coordinator,
Van's Comfortemp

Karl, thanks for the question. My initial thought was, are you using a phase monitor? Then, I decided to ask our resident tech guy, Woody McAllister. His experience includes being an HVAC/R contractor and location manager for one of our Totaline sales centers in South Texas. Hopefully, his answer below gives you some insight. And don't forget your Totaline counter sales team. They love to help and they sell all the parts and supplies you need. They should be able to help you get the literature Woody refers to.

POTENTIAL CAUSES

“My experience has shown that there are a few things that could cause a failure of an electrical device, and the cause is not electrical or mechanical at all.

“Most of our two-speed units have a built-in phase monitoring system labeled control modules or control boards, which are capable of providing precise control of the equipment and monitoring. But if the system is not properly configured, this could cause the same symptoms as a failure such as stuck potential relays or shorted run capacitors; for example, improperly sized line sets allow the liquid refrigerant to settle in the suction line, so when there is a call for cooling, the compressor is under a load of liquid instead of gas, which lags on the compressor and makes it difficult to start. It could do this for several starts and finally fail the starting device.

“Another failure is the improperly charged system — sometimes it is difficult to charge a unit under certain conditions using the recommended sub cooling or super heat charts. These charging charts are based on ARI conditions, and, most of the time, we do not find ourselves in the luxury of those conditions. Improperly configured line sets and improperly charged units have been a major cause of failures.”

SOLUTIONS

“Solutions are simple: follow the guidelines of the PURON® and R22 Application Guideline and Service Manual for Air Conditioners and Heat Pumps using Puron Refrigerant, catalog number 533-781, and the Application Guideline and Service Manual for Residential Air Conditioning and Heat Pumps using R22, catalog number 24-25-1SM.

“For charging any system of any size whether it is an air conditioner or heat pump, charge by the weight-in method. You will find this in any of the residential AC and heat pump product installation instructions. Using this method is the most accurate under any condition. You will also find that it provides your customer with the most reliable, efficient equipment on the market. Following the guidelines and installation manuals of any equipment will help prevent future failures.”

Thank you, Woody! Because I used his question in this column, Karl gets Totaline FREE STUFF. Do you have an HVAC/R question? Send it to me, and if I use it here, you get FREE STUFF!

James.Flynn@totaline.com

Jim Flynn is training manager for Totaline sales centers and has 35 years of experience in HVAC/R. Every month, we challenge readers to Stump Jim Flynn with a question about Totaline sales centers and the industry. Contact him at James.Flynn@totaline.com.