Hi there, thanks for sharing your experience with us. We are sorry to hear that Nest Thermostat only works with cooling and having issues when it comes with heating.
Some possible causes of this are the following:
- The thermostat is being miswired.
- Possible need of C wire (if you don't have, for power sharing issue).
- Incorrect orientation for heat pump system.
- Incompatible heating system.
- Thermostat is defective.
We would like to know more about what happened so we can work together to troubleshoot the issue and help you improve your experience. Please reach out to our support team here: https://support.google.com/googlenest/gethelp