In this episode of the HVAC Know It All Podcast, Host Gary McCreadie Director of Player Development and Head Coach at Shelburne Soccer Club and President of McCreadie HVAC & Refrigeration Services and HVAC Know It All Inc, shares a service call involving a Lennox rooftop unit that kept shutting down on high pressure. Gary explains how he checked the airflow, condenser, pressure switch, refrigerant pressures, contactor, filter drier, and TX valve while trying to find the restriction. He also describes how equalizing the system pressures and tapping the TX valve helped the unit start running again. The episode covers compressor pressure relief, microchannel coil limits, the use of a system lubricant, and the value of testing different solutions before replacing expensive parts.

Gary discusses a difficult service call involving a Lennox rooftop unit that kept shutting down on high pressure. He explains how he checked the airflow, condenser fan, pressure switch, refrigerant pressures, contactor, filter drier, and TX valve while searching for the cause. The episode covers how equalizing the system pressures and tapping the TX valve helped the unit run again, along with compressor pressure relief, microchannel coil limits, system additives, and the importance of trying different tests before replacing costly parts.

Expect to Learn:

• How a stuck TX valve can cause low suction pressure and high head pressure.

• Why checking airflow, fans, coils, and pressure switches should come before using gauges.

• How equalizing system pressures and tapping the TX valve helped restore cooling.

• Why compressor relief valves and contactors are important for system protection.

• How testing different solutions can prevent unnecessary and costly refrigeration repairs.

Episode Highlights:

[00:00] - Sponsor: Factory Direct Filters ad

[01:33] - Intro: Service call overview & 30-year career context

[03:22] - High pressure switch explained & rapid cycling issue

[05:46] - Pressure differential theory & refrigerant logging in condenser

[08:19] - Second visit: Zero low-side pressure, high-side off the charts

[11:07] - Fix attempt: Equalizing pressure & smacking TX valve works

[15:07] - Contactor replacement & SmartShot additive experiment

[19:34] - Final lesson: Don't give up, try new approaches, learn from every call

This Episode is Kindly Sponsored by: Cintas: https://www.cintas.com/hvacknowitall

Cool Air Products: https://www.coolairproducts.net/

Factory Direct Filters: https://www.factorydirectfilters.com/

SupplyHouse: https://www.supplyhouse.com/tm Use promo code HKIA5 to get 5% off your first order at Supplyhouse!

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LinkedIn: https://www.linkedin.com/in/gary-mccreadie-38217a77/

Website: https://www.hvacknowitall.com

LinkedIn - HVAC Know It All Inc.: https://www.linkedin.com/company/hvac-know-it-all-inc

McCreadie HVAC & Refrigeration Services: https://www.linkedin.com/company/mccreadie-hvac-refrigeration-services/

Shelburne Soccer Club: https://shelburnesoccerclub.sportngin.com/

Facebook: https://www.facebook.com/people/HVAC-Know-It-All-2/61569643061429/

Instagram: https://www.instagram.com/hvacknowitall1/

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Apple Podcast: https://podcasts.apple.com/us/podcast/hvac-know-it-all-podcast/id1359253455