Heating, Air Conditioning, Fridge, HVAC/A/C drain


QUESTION: My 2 a/c units are located in the attic and the pans have water when the a/c is on.  I believe I need to make sure the primary drain isn't blocked or partially blocked.  How can I tell where the primary drain empties?  
Thank you!

Your air conditioners are outside, the units in your attic are air handlers, your air handlers have a cooling coil inside, the cooling coils "usually" have a drip pan under them, the drip pan "usually" has two drain connections, the lower one coming off of the unit is the primary drain line, the installer picks the easiest, best place to run the drain line to,You need to follow that drain line to see where it goes and what it drains into?
The higher drain connection on the unit is an over flow drain that should be ran to the outside of the roof eves where any water in it would drip down to where you could see it easily indicating that the main drain is clogged and needs service.

---------- FOLLOW-UP ----------

QUESTION: Mr. Barnhart,
Thank you for correcting my terminology. The master bath is the closest bathroom, located almost directly under the attic. It has 2 sinks, and it appears that the air handler serving the downstairs of the house may drain into one sink's plumbing and the system serving the upstairs may drain into the other sink's plumbing. I'm assuming that these drains need to be cleared, and perhaps there is also a partial clog in the overflow drain because the auxiliary pan fills but the drip from the eves is slow. Are these reasonable assumptions?
Thank you!

There shouldn't be any water/moisture in the over flow drains,
If your getting a drip or flow out of the over flow drains you need to clean out the main/ primary drain/drains.
A common place  for attic drains to run to is a plumbing vent stack that run's up through the roof?
Again the draining system is completely up to the installers discretion.
I have no idea what your drain line consists of?

Heating, Air Conditioning, Fridge, HVAC

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Jim Barnhart


Fifty + years conditioning the air.


Answer questions about , residential and commercial. Answer questions about sheet metal fabrication. Fifty years plus experience. No answers for oil equipment, No answers for kitchen appliances, No answers for laundry appliances, I don't specialize in one particular area of the HVAC area, I'm more of a General Practitioner, Limited in refrigeration/

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