Water leaking from central AC unit -- is it fixable?

Old 10-23-01, 01:24 PM
Visiting Guest
Posts: n/a
I have a Carrier central AC unit (electric, model 28,38 or 40) that was made in 1986. I hadn't used it for about 2 months, but recently turned it back on. It's cooling fine and ran for about 10 hours straight overnight (which isn't out of the ordinary, the house was pretty hot). However, when I got up this morning, I heard water dripping from the air duct above it and running down the front of the unit and into the unit itself. The overflow (?) drip line outside was dripping condensation fine from unit. It continued dripping for a good few hours after the unit was turned off.

Now, I don't know if this unit has ever been serviced (the interior coils). I doubt it has (we only got this house 2 years ago, and the previous owners had neglected to change the air filter for the 7 years they lived here, but the inspector we hired said the unit looked good for being 10 years old). The top of the metal panel that houses the unit has some sort of tape across it, it looks and feels like plaster. Regardless, it looks like the water is coming from above this box.

Any help would be appreciated. I'm hoping this thing is salvageable. We're military, so we're only likely to be here a few more years and don't want to sink any more money into this place!
Old 10-23-01, 01:50 PM
hvac4u's Avatar
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,145
Received 0 Votes on 0 Posts
dirty air filter, dirty evap coil or low charge...go for the filter first
Old 10-23-01, 01:56 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,197
Received 53 Votes on 49 Posts
Lucky you if you still need airconditioning. Our ground is pretty white right now.
It sounds like the evaperator coil could be plugged with dirt.
You can check it if you take apart the ductwork in front of the coil and inspect the upstream side of the coil surface.
Some coils have a inspection cover that has to be removed.
If you shine a flashlight through it and look from the other side you will tell how dirty it is.
If it has electric heat be sure to turn off the breaker as the elements are probably live.
Could also be low refrigerant charge, bad fan motor or belt or blocked duct.
Check coil first.
Old 10-23-01, 01:58 PM
Visiting Guest
Posts: n/a
The filter is brand spanking new, so that one's ruled out.

I'd like to get a look at the coils, but the panel seems sealed up by this plaster-like tape that runs around the entire unit. It doesn't seem made for easy access at all. Do I need to cut through this stuff to get at the panel? And how do I seal it back up once I'm done with the coils? (This is my first time dealing with HVAC!!).
Old 10-23-01, 02:40 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,197
Received 53 Votes on 49 Posts
The plaster like material is probably fiberglass insulation covered with cotton and coated with a whitewash like material. You will have to cut it with a razor knife and remove enough to get at what you want to see.
Normally you would try to access the ductwork near where the refrigerant lines enter. It usually works better when you cut out an area much larger than you need because you won't have to chop it out in pieces which is harder to replace. Duct tape will sometimes hold it when replacing it or you could use thin cotton and some type of patching compound to stick it back together.
Old 10-24-01, 02:30 AM
Visiting Guest
Posts: n/a
Thank you all so far!

I'm the spouse of the wookie_mouse) So, after examining the unit thoroughly on the exterior and with my limited knowledge of HVAC units, this is what I have so far, starting from the bottom of the unit:

underside intake grill - clean
bottom catch pan - free-range dust-bunnies and puddles
filter - clean (replaced monthly)
fan - a little dusty, but was working fine
burner - currently off, but no problems with pilot or
burners, heats fine (used recently)
heat exchanger - did not take off panel, but working fine
drainage piping - intact with some mineral deposits on and
around the joints
cooling lines - intact and insulated

cooling coil - unknown...the 'box' around it has a service panel, however all around the top seam of where the coil meets the outflow duct, there is taping (much like plaster cast material, about 1/16th of an inch thick) which covers the screws holding the panel on, so I have not yet opened it. Considering the previous occupants (who had never maintained ANYTHING in the house) I expect to be attacked by the raging dust-rhino trapped on the coil.

So, here is my dilema, should I cut that 'tape' to access the panel or would I be disrupting some critical insulation/sealant?

I think that if I can get access to the coil, I could at least clean it and see if there are some other issues.

Once off and on replacement, should I just reseal the panel like it was with duct tape?

I appreciate your input thus far.
Old 10-24-01, 09:40 AM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,197
Received 53 Votes on 49 Posts
The sealing material you are looking at is probably a duct sealant.
By all means, cut it to gain access to whatever you have to and just use duct tape to reseal it.
Consider yourself lucky if this seal and a few screws lets you gain access to the coil.
I come across many installations where the duct has to be cut to get at it.
Once you get to the coil you have to be able to see both sides of it. The down stream side will most likely be spotless and the upstream could look like a piece of felt is covering it.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: