No. Yes. Sort of. If you have the skill set and want to give it a shot, have at it. However if it’s best practice for a PMT to not touch that asset, it’s on you if you cause more damage.
This is one of those things that varies region to region. In my area, if you can fix it, do it. Nobody will fault you if you vendor it out though.
Example: SBux and Food Ave freezers are prone to ice build up. I can vendor it out for $200-$400+ Or I can take the cover off the evaporator and use a heat gun to melt it off for an hour or 2. A couple hundred dollar doesn’t sound like much but it adds up over the course of a year.
PMT owns plumbing as far as stoppages and leaks until we no longer have the tooling, skill, or time to repair said issue.