Staff Answer
Sep 25, 2026 - 02:24 AM
The easiest way to know what a heater should read is to use the wattage and voltage printed on its label. Resistance equals volts squared divided by watts. For example, a 325 watt heater at 120V should read about 44 ohms, and a 225 watt heater about 64 ohms. If yours reads open (no reading), it's bad. For the N641, the AC heater is the 621702 or, on newer units, the 638374/ 50822. If you have any questions, just reach out at info@rvfridgeguys.com or call us at 800-712-8822. You can find everything we carry at www.rvfridgeguys.com.
