I think the coil is clogged on my furnace. I am thinking this because of two main reasons:


1. I'm trying to run the A/C and there's nothing coming out of the vents, but the fan is running on my furnace and I can feel cool air blowing out of the seals around the coil.

2. The box on the bottom of my furnace was built too small, and they cut the side out of the metal to allow for extra air flow. When I bought the place, there was no filter there and the inside of the furnace was filthy. I just replaced a circuit board a couple of months ago because of it.


I used my home warranty to pay for the circuit board, but this is considered cleaning and the warranty won't pay for it. I'm tight on cash right now, so if I could do this myself, that would be great!

Could I do this myself and how would I go about figuring this out?

Thanks in advance for any help!

You will need to clean the underside of the coil. Try to vacuum off all you can can and then wash it with coil cleaner and water. Sometimes the hand pump-up spray bottles you can purchase at garden stores work good. You need to be careful not to get any water on the motor or any other electrical devices. You also need to figure out a way to instal a filter or you'll continue to have problems. Don't run the AC until you get your coil clean, the coil will ice up and this can cause slugging liquid refrigerant back to the compressor and that's not a good thing.

You will need to clean the underside of the coil. Try to vacuum off all you can can and then wash it with coil cleaner and water. Sometimes the hand pump-up spray bottles you can purchase at garden stores work good. You need to be careful not to get any water on the motor or any other electrical devices. You also need to figure out a way to instal a filter or you'll continue to have problems. Don't run the AC until you get your coil clean, the coil will ice up and this can cause slugging liquid refrigerant back to the compressor and that's not a good thing.


Thanks for your response!


So -- from what I described, it's sounds like the coil is clogged?

If you're been running the blower without a filter, it's most likely dirty. I'd start by cleaning the coil and then look at other possibilities. Is your blower cage clean? Have any dampers been closed? Is it a multi speed motor, if so is it running on the high speed?

Good luck

If you're been running the blower without a filter, it's most likely dirty. I'd start by cleaning the coil and then look at other possibilities.



I can't get to the left side or top of the coil. The left side of my furnace is blocked in by a duct. Here's a couple pics...



Anyone have any ideas?

Whoops? Lmao - you just made my day -- Savage

Woops! Wrong pics! I couldn't figure out how to edit them...

If your careful, you can probably disconnect the drain line and just slide the coil out far enough to clean the bottom of it. Just be careful and don't let it fall. You may have to cut the front of the duct work and screw it back together after your done. Make sure you clean the bottom side real good.

If your careful, you can probably disconnect the drain line and just slide the coil out far enough to clean the bottom of it. Just be careful and don't let it fall. You may have to cut the front of the duct work and screw it back together after your done. Make sure you clean the bottom side real good.


There's one maybe two copper lines that run into it too. They are wrapped in black insulation. (to the left of the pvc in the photos) How could I get to the bottom of this thing? I wish I could just spray 409 or coil cleaner inside there and presto! Clean!

It looks to me as though you can pull out the coil far enough without causing any damage to the refrigerant lines. Just remove any clamps around the lines and they should pull out away from the duct with the coil. You just need to get the A coil out far enough to see the bottom side. Then you should be able to brush it off or clean it with a good vacuum cleaner. If you can wash it with a cleaner and some water without losing a lot down on the burner, that will be good to do as well.

It looks to me as though you can pull out the coil far enough without causing any damage to the refrigerant lines. Just remove any clamps around the lines and they should pull out away from the duct with the coil. You just need to get the A coil out far enough to see the bottom side. Then you should be able to brush it off or clean it with a good vacuum cleaner. If you can wash it with a cleaner and some water without loosing a lot down on the burner, that will be good to do as well.

I can't figure out how to disconnect the drain line. It looks like it will screw off, but when I turn it, it seems like the whole thing is going to break. I think it's bonded with some kind of adhesive.

Sorry if I seem like a total idiot when it comes to this stuff. I guess that's why I'm on this website though!

Can you post a pic of the connection at the hose? [just the connection --no kids lol] -- Savage

can you post a pic of the connection at the hose? [just the connection --no kids lol] -- Savage


See Below:

Cut the pvc pipe with a hacksaw about 3 inches to the left of the threaded connection /get a slip connector / glue / primer for reassembly. -- please note that I am a jack of all trades not a hvac tech. -- Savage

Get a 5/16 wrench and nut driver remove the triangle metal in the center of the coil and clean it in the hole as we say. You don't have to pull the coil to clean it.

The silver metal in the front of your coil, the metal I see in the pictures, is held in place by several 5/16th metal screws. Remove the screws and work the metal out of the way. Use some heavy paper or a plastic drop cloth and lay it on you heat exchanger when you get th metal out of the way. This is to catch any trash that you get out of the coil. Use a flashlight and look at the coil if it is dirty then you can clean it.
The way I clean a coil in a situation like this: I use a spray bottle and I spray the coil lightly with a solution like 409, I only get the gunk on the coil moist not dripping. I then use a brass bristle brush ( You can get them at a good automotive store, they are a little bigger that a toothbrush). With this brush I start at the top of the coil and work down, sometime when you get a strip started it will then peel off al the way to the bottom of the coil, but if it won't just keep brushing all the way down each side of the coil. You will see the shinney aluminum as you clean the coil.
When you are finished make sure you remove the paper or drop cloth from the furnace.
If this works for you let me know.