The Deep End with Roman Baugh: Live Call, Grounded Compressor, Mitsubishi Mini-Split
HVAC School - For Techs, By Techs
Bryan Orr
4.9 • 1K Ratings
🗓️ 2 June 2026
⏱️ 15 minutes
🧾️ Download transcript
Summary
In this short podcast, Roman Baugh takes over with his new series, "The Deep End," where he shares tech support conversations. This time, Roman is on the other end of a live tech support call about a grounded compressor with an existing Mitsubishi mini-split (Mr. Slim heat pump). The unit in this case had an unclear service history due to the homeowner moving in recently.
In this issue, the compressor kicked on and kicked off immediately. After the technician in this scenario told tech support that he had no continuity from the compressor to ground, tech support asked him to check the resistance (which was 43 ohms from black to ground and 43 from white to ground). Tech support concluded that the compressor was grounded, and it needed to be replaced (along with the PCB). However, the resistance disappeared mid-call, and intermittent resistance readings don't always indicate a failed winding; it's worth noting that cool ambient temperatures that enable liquid refrigerant to migrate into the compressor could potentially skew electrical readings.
Roman recommended shutting the system down and trying to get the system to run. His rationale was that if the unit ran and didn't keep stopping, the system may have been overcharged or lacking a crankcase heater. However, that did not show any improvement in operation; the compressor rattled for about a second and shut off. A resistance test confirmed that the compressor was grounded, pointing to a mechanical issue with the compressor and not just a one-off instance of refrigerant migration. This type of failure can happen when there are repeated instances of liquid refrigerant in the crankcase over time.
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Transcript
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| 0:00.0 | This episode of the HVAC School podcast is brought to you by our trusted sponsors. |
| 0:10.8 | Refrigeration technologies and their Viper aerosol coil cleaner for condensers and evaporators. |
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| 0:44.0 | Find out more at refrigetec.com. |
| 0:47.3 | Carrier and carrier.com. |
| 0:49.9 | Carrier has been a long-term sponsor of the podcast. |
| 0:52.5 | They've made it possible very early on for us to do |
| 0:54.9 | what we do, and they are the products that we sell day in and day out, everything from |
| 0:59.0 | single stage equipment all the way up to the green speed extreme, one of the most efficient |
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| 1:14.1 | Navak at Navakglobal.com and the Nexus digital manifold gauges, the NX1 and NX4, which also |
| 1:23.0 | comes with temperature clamps. |
| 1:25.2 | The NX1 is Navak's classic digital manifold, supports 72 |
| 1:30.3 | refrigerant types, including the newer A2L refrigerants, has a working pressure of 600 PSI, |
| 1:36.9 | which most common refrigerants won't go anywhere near, has quarter turn ball valves for easy |
| 1:42.3 | operation, for charging, recovery, and the like, and the |
| 1:45.9 | NX4 just takes the NX1 a step further, four valves, and a three-quarter-inch vacuum port. |
... |
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