Depending on the car and where the coil is. Best solution I have is do a Google search for the make, model, and year for AC drain line cleaning. Cheaper than buying a repair manual. I have done this for the three cars in my family.
Hi Cheryl, it's not too difficult depending on what type of car you have. I'm hoping this article will give you some guidence - https://cartreatments.com/clean-car-air-conditioner-filter/
Here's a link tht might help you:
I specialize in this, but you Gotta wear the serious gear.
Do you know for sure, that your drain is really plugged?
In my experience, it is not the drain that is plugged, it is the condenser coil‘s that are contaminated with mold.
If You know for sure that the hose is plugged, then you need to find out where the plug is.
If it is the condenser coil’s, then I can tell you how to clean them with mold killer, please let me know.