acservicetech_Web_Add_1_3 (1).png
ACSERVICETECH AccuTrak Video Ad 3.jpg
Search
  • Craig Migliacco

Can I measure a Negative Subcooling When Checking the Charge? (Quick Tip)

Updated: Jul 3


The answer is no because the refrigerant rejects heat in the condenser so the pressure and temperature of the refrigerant should lower. The refrigerant starts off in the condenser as a superheated vapor and after it rejects heat, it changes from a vapor state to saturated. After it rejects enough heat, the refrigerant changes to a subcooled liquid. In this picture, we see a saturated temperature of 105°F and a line temp of 93°F.


105 - 93 = 12°F of Subcooling

It is possible for the refrigerant to stay saturated instead of subcooling if the system is extremely low on refrigerant. A system that is very low on refrigerant may read 0-3 degrees of subcooling. Typically, there will be at least a small amount of subcooling measured. If the refrigerant is rejecting heat at the condenser, there is no way for the pressure or temperature of the refrigerant to increase as it makes its way through the condenser. It will either exit the condenser as saturated (saturated is liquid and vapor refrigerant in the same location) in a low refrigerant scenario or the refrigerant will be subcooled (subcooling is the lowering in temperature of the liquid refrigerant). If you are measuring negative subcooling, make sure your measurement locations are correct, otherwise you may want to recalibrate your tools!

Be sure to check out the full Subcooling Charging Method Article here!


Articles: https://www.acservicetech.com/articles Quizzes: https://www.acservicetech.com/quizzes Calculators: https://www.acservicetech.com/hvac-calculators Quick Tips: https://www.facebook.com/acservicetech Ebook, Book, Workbook, Quick Cards: https://www.acservicetech.com/ac-book Book, Workbook, & Cards: https://www.amazon.com/shop/acservicetech Tool Lists: https://www.amazon.com/shop/acservicetech

AC SERVICE TECH, LLC

Thanks for all your continued support! I appreciate all the comments, questions, and responses that I receive from each of you. I look forward to responding to many more! If you have an HVACR related question, drop it in the comment section of one of the YouTube videos at the AC Service Tech YouTube Channel and I will do my best to respond.

 

For business related inquires email us at info@acservicetech.com

Check back regularly as we are always updating and improving this website!

Updates List

© 2019 AC Service Tech, LLC.