Lets take a look at the specific verbiage from the Section 608 EPA Certification for Air Conditioning and Refrigeration.
If a Heat Pump control board goes out and needs to be replaced, can anyone order and replace the control board? You're not working with refrigerant. But do you still need a HVAC certification?
Replacing the control board on a Heat Pump falls under the "repair" part of the verbiage above. The answer is "yes." A technician needs to have a valid HVAC certification to "maintain, service, repair or dispose of appliances that contain regulated refrigerants." A Heat Pump contains regulated refrigerants. If you hire someone to work on your swimming pool heat pump, please make sure they are HVAC certified.
Here at Hawaii Pool and Spa, we hold the Universal EPA Certification from the ESCO Institute which qualifies us to work on any Type I, Type II, or Type III appliance.