I have a 4 ton Waterfurnace Envision split system with the blower located in the attic and the heat pump in the basement installed in 2012, running without incident since. Every time I've changed the filter, the condensate pan underneath the blower has been completely dry. The weather this past weekend in the Northeast was excessively hot and humid and apparently the water sensor in the condensate pan under the blower unit was triggered on Saturday because of significant water accumulation. I opened up the blower unit and the pan inside underneath the coil was full as well. I drained both pans (probably 3-6 gallons). I checked the drain line which must've been clogged (banged it a little bit), because I drained through the side plugged which is higher than the drain line. but I didn't auger the line but from what I could tell from the drain end in the basement was that no water was coming through it. This got the system back up and running Saturday evening. Sunday morning, I went to check on it again. Water was draining coming through the end in the basement, but there was additional accumulation in both condensate pans (inside pan under the coils and outside pan), probably 1-2 gallons, but the system was otherwise working. I removed the water. The water in the inside pan is about 0.5" high but below the drain line. The cold air wasn't super cold, but it was able to keep up with the 95+ heat througout the day. I checked again this morning (Monday) and system was working but there was still additional accumulation of about 1-2 gallons, which I removed again. I checked the loop EWT & LWT and they are generally in the high 70s (I haven't been running a log prior to the issue). When the system is running the temps are usually about 4 degrees apart, but when it stops, it looks like the EWT can actually be higher than the LWT but I thought that might be something wrong with my measuring technique (or not), but I thought it was worth mentioning. Also, I've never had the loop pressure checked or had the system otherwise maintained since installation, something I probably should get done now, but I thought it would make sense to do some diagnosing first. I assume this condensation is not normal even in high heat. Any suggestions of what might be causing it or what I should inspect?