Arrived on site to diagnose indoor units not working in heat mode. After our initial inspection, we ran all three heads in maximum heating for 30-40minutes. The units eventually went into defrost mode. The indoor head fans stopped and the outdoor fan also stopped but the compressor continued to run. This is completely normal operation for defrost mode. After about 10 minutes the indoor heads started up again. Informed Colleen that we believe what they’ve been experiencing is the unit going into defrost mode. This can happen every 45minutes and last up to 30minutes depending on the severity of the the frost on the outdoor unit. As of now, system is operating as expected. Colleen will take a video of the heads next time she believes there is an issue to help us track down what is happening. Thank you for your patience!