One of my HVAC units has water pooling in the tray.  The float is doing its job and cutting the unit off.  Should I be concerned that water is collecting like it is?  I completely drained the pan just to see how quickly it will come back, because the drain that is in there is slightly elevated and will allow water to stand even if it is below the level that would trip the float.  What causes this and is there anything specific that I need to do to troubleshoot it?  Thanks.

Blake

Im not a pro HVAC guy but i have some general knowledge on HVAC that might help you. Did you check the outside drain pipe and make sure it is dripping the condensate? If it isnt dripping the drain may be plugged. I once had a Slug get in mine and caused the same scenerio that you are dealing with

For a detailed account, what cycle is it running on? In the south, you might be on AC. Here, right now the heater is on. What has been running lately?

First, if water is pooling in the drip pan, there is another problem you have to identify
First though, your secondary drain is plugged up.  If you have compressed air, you can blow it out. then, add some bleach or other cleaner and blow it through.  then add some more
Water will come into the drip pan if your coil drain is plugged up also.  Repeat the above process to clear the drain.
this is the most likely process.
Other causes could be a dirty coil, low on freon ( coil and piping would be freezing up aslo.)
Hopefully, its just the drain stopped up.
If you still have a problem after that, just fly me up there for a all expense weekend for 2 and I'll take care of it for ya.

blake, since you didnt say what exactly we are dealing with, a window unit a/c, furnace with A coil set up, heat pump setup, or a external heating/cooling  unit thats like a roof top but sitting on the ground with duct work going into residence,

so I will take a stab at possiblilities, like others have said plugged drain on the pan, but if its a Acoil set up or the roof top type, check and see if your water trap is not sucking air , have seen situations that you would have enough negative pressure that it would hold the water in the unit, also is the drain hooked up to a condensate pump? could be a plug way down the line by the pump, seen my  share of things over the yrs

good luck

Actually, a Shop Vac is your friend.  Suck from the outside drain, some integrate into the sewer/septic system.  Using a vac instead of compressed air is MUCH LESS MESSY.  Plus, you can drain the pan this way.  



Clean the evap coils. Smeg from them is making a bacterial goo which clogged the drain.  Clean filter and clean coils are a happy system.

Thanks for the replies.  When I checked it this morning it was completely dry.  I'll keep an eye on it.  Probably not a bad idea to flush the drain lines and clean the evaporators...I guess that would be seasonal maintenance.  

yep

Most installations around here (TN.) don't use a secondary drain line.



( installed for 12 years in Texas also, I know what your saying about that )



They just install a drain pan with a float switch wired into the low voltage that shuts the AC off when the pan fills up with water.



The indoor blower will still move air, but the ac will cut off.



Clogged main drain is probably the cause, but if your indoor coil froze up and thawed out, it can make that sort of mess also.



OP, what part of TN are you in?

If you have water in the auxiliary drain pan, you probably have a problem with the primary drain. Most likely a stopped up drain line or excessive buildup in the pan. Clean the primary drain line out. You can use a wet-vac,  compressed air, or back flush the line with a water hose. adding a half cup of bleach periodically will help control algae buildup.