Popping noise coming from a/c drain pipe?

Trane
Model # TVF030A 140A1
MFR Date 09/2002
12 SEER
Motor HP 1/3

While the a/c is running I can hear popping noises coming from the drain pipe. The main drain pipe runs in to the same drain as the washer in the utility room. We change the air filter frequently, and pour plenty of vinegar down the drain pipe at the same time of filter change. The secondary drain pipe that goes out to the back patio isn't leaking.

I've noticed this popping sound about two years ago, but didn't think nothing of it. House is still cooling, and electricity bill is about the same. This noise comes and goes. It's not always popping when the a/c is on. I have noticed it's been a quite humid the last couple of days. And it's been popping since it's been humid. Does humidity have anything to do with that noise? Should I be worried about this?

EDIT: We're running the system at 76 degrees. It's been in the high 90's lately if that helps any. Thanks again.

 

Try adding a vent after the trap. Your trap is probably getting sucked dry when the washer drains.

 

With Matt here. The pipe that the AC drain and washer go into . Is it like open at the top??? so it works as a vent???? Use clorox to clean the drain

ED

 

Sorry guys I didn't make myself clear. It's the actual a/c unit that's making the popping noise. The noise is resonating through the main a/c drain pipe. It's most audible at the end of the pipe just before it enters the drain downstairs. Hope that clears things up.

 

Does the noise occur when the control is set to OFF and the fan is set to ON?

 

I tried just running the fan, and it doesn't make any noises. I then turned the a/c back on, no noise. I turned the thermostat down to 65, noise comes back. We're figuring that it makes the popping sound when the a/c unit is working the hardest.

We just had our home warranty guy come take a look at it. Of course it wasn't making any noise when he was here. He said he is going to send out an a/c person out to check to see what it could be. I'll find out this friday. Hopefully we can make it do the popping sound so he can see what it going on.

EDIT: Oh yeah, when the a/c stops cycling it continues to make the noise. It makes the noise for about 10minutes after the a/c starts, while the a/c is on, and roughly 10-15minutes after the a/c stops. That's what I've noticed.

Oh, and sorry it took me so long to respond.

 

It sounds like you dont have a P trap there on the drain line. When it does make the noise put your hand over the end of the drain pipe and see if it stops.

ED

 

Ok, more on that. There this cap that I remove to pour vinegar down the main drain pipe to try to keep it clean. The pipe with the black insulation is the main pipe. I guess the other is the secondary pipe?




I noticed when it was making the noise I uncapped it, and the noise went away.



Uncapped.




This is where the main pipe drains downstairs. Should I be concerned about that brown color?





So do you think that my main drain is clogging up? I hope that's the only problem I have. If so, what would you recommend to pour down there to unclogg it? I do have some ZEP Drain Care on hand... should I pour that down there?

 

I don't think it has a p trap. Does it need one?

 

Thats for sure. The picture's are good . But I dont see a p trap you have to have one so the blower dont suck back the water in the unit Yes you have to keep that cap on all the time. Clorox
Is what you want to clean the drain of mold .
Could you work a trap on the end there and hang over the drain like it is now??

ED

 

I agree with Ed if this unit blows air up but I see no practical way of installing one. If it blows down, a trap is neither needed nor desired.

 

My a/c unit is upstairs, and drains down to the bottom floor. Is that what you mean? Or are you talking about a blower unit blowing through the pipe? I'm a little confused. Well, the warranty guy is coming tomorrow to check out the noise. I'm still a little stumped about that noise. When the cap is on it pops. When it's off it doesn't. I'll start pouring bleach through the pipe right away to help clean it. Thanks guys.

 

Open the blower compartment & look at how the blower is mounted. If it is attached with the square blower outlet pointed up, the air flow is up. If the outlet is pointed down, the air flow is down. If the air flow is downward, you do not need or want a trap.

 

I haven't had the chance to look into the blower compartment yet. The warranty guys came over to check it out while I was at work. They told my wife that the a/c unit was fine. She explained to them about the noise. They further looked into it. They told her that they needed to install a p-trap and did so. I haven't heard the noise yet, so lets hope that was the cause of the noise. Thanks guys for your help.

 

Ill put it this way You are one lucky Dude.
With that unit upstairs and no P trap that you didnt end up with water all over the place

ED Its hard to get good hvac help now days