A/C Issues

[Rocket79]

I'm well aware it's time to call someone, I just want some advice on what's going on so I don't end up paying for things I don't need to.

Problem; Trane A/C less than 2 years old. Compressor runs for an hour or so, Cools OK. After a while I get a loud humming noise and it stops cooling. Compressor fan still running. Compressor motor gets pretty warm, but not too hot to touch. Evaporator not iced over. Suction line cool to touch- not iced, liquid line not warm or cool. (at compressor) Temp split at coil is ok on start up (16-17 degrees) the longer the unit runs the worse the split gets.

What I've done/checked; Changed filters. Changed batteries in thermostat. Cleaned condenser coil. Checked water drains (float switch). Measured contactor both normal and during humming, no change at line voltage or 24v line. Checked compressor motor for resistance and short to ground,, 0.8 common to run, 1.6 common to start. 2.5 run to start. Check capacitor, measures within 1% of label.

After humming starts; Everything measures out the same, resistance is only slightly higher. Still have continuity between common, run, and start so I don't think it is out on thermal overload.

 

[Rockhead261]

Where is the humming coming from?

 

[Rocket79]

Compressor motor is humming.

If it makes any sense, (and something I'm more familiar with) it reminds me of a pump in a hydraulic system "dead heading"... i.e. pressure on both sides.

Shutting the compressor down resolves the issue fairly quickly, but it also returns quickly. The only way to get it to run for an hour + is to leave it off overnight.

Ambient temps today are only upper 80's, system was running fine between 70-105. failure occurred quite suddenly.

 

[JackDiddly]

Without actually reading the system pressure on both gauges (high and low) while it is running you won't be able to figure much more out. To me it sounds like there could be a really slow leak somewhere in the system that was not found at the time of installation and system running very low on refrigerant. ?

 

[sms1974]

hard to diagnose without system pressures... could be a refrigerant quantity (over or under charged)or an expansion valve issue.

 

[LS6 Tommy]

Could be a host of things. Plugged condenser coil, inefficient compresor, short cycling (host of reasons for that, too), lots of others...

Tommy

 

[Rockhead261]

Internal pressure relief.

 

[Rocket79]

Tech claimed compressor manufacturer was using a rust inhibitor that reacts with 410-a and flakes inside system. Inhibitor no longer being used. This flaking blocks expansion valve. He added some kind of additive to break this up. I'm still under warranty for a few more months, so the service call didn't cost me anything.

But one more question. Anybody ever heard of this? Or is this a "get me by" until warranty is out and I'm paying to replace the valve?

 

[brewchief]

Talked to one of my supply houses yesterday about this, this is a real deal and she said it has fixed 99% of systems they have had this problem with. If it doesn't fix it the warranty should still cover txv replacement.

Sent from my SM-G900V using Tapatalk

 

[bonneyman]

Talked to one of my supply houses yesterday about this, this is a real deal and she said it has fixed 99% of systems they have had this problem with. If it doesn't fix it the warranty should still cover txv replacement.

Sent from my SM-G900V using Tapatalk

What's the name of this additive? I've never heard of it.

 

[Rocket79]

Talked to one of my supply houses yesterday about this, this is a real deal and she said it has fixed 99% of systems they have had this problem with. If it doesn't fix it the warranty should still cover txv replacement.

That's word-for-word was the tech told me. Thanks for making me feel good and fuzzy about it.

On a side note, the new manager of the HVAC company has always treated me right. I guess I just needed someone to remove the 1% of doubt.

 

[Mike007]

A member on the forum had the same issue recently.

http://www.garagejournal.com/forum/showthread.php?t=299347

 

[Rocket79]

A member on the forum had the same issue recently.

http://www.garagejournal.com/forum/showthread.php?t=299347

I feel a little bad saying this, but I'm glad I'm not the only "lucky" one. Thanks for the link.

 

[LS6 Tommy]

What's the name of this additive? I've never heard of it.

Snake Oil?

AFAIC, the only way to "fix" a plugged TXV is to disassemble it, clean it and reassemble it or just flat out replace it.

Tommy

 

[Mike007]

This is the product my distributer is giving out:

http://www.nucalgon.com/products/oils/a-c-re-new

I will say this, it did work. But I'm not a big believer in repairs in a bottle. Last one I did the TXV was running almost 50* superheat. I put this **** in and 2 days later it was down to 30*. At this point it was cooling. I returned a week later and it was down to 16* and the pressures looked good.

At the end of the day, I would rather just put in a new TXV. The AC works immediately and the customer is happy. In this case I end up with more time ******* using the AC Renew then I would have swapping the TXV out. But that's not what the manufacturers want. They claim the new valve will just clog up too.

 

[theoldwizard1]

at the end of the day, i would rather just put in a new txv. the ac works immediately and the customer is happy. In this case i end up with more time ******* using the ac renew then i would have swapping the txv out. But that's not what the manufacturers want. They claim the new valve will just clog up too.

concur !

 

[theoldwizard1]

at the end of the day, i would rather just put in a new txv. the ac works immediately and the customer is happy. In this case i end up with more time ******* using the ac renew then i would have swapping the txv out. But that's not what the manufacturers want. They claim the new valve will just clog up too.

concur !

A member on the forum had the same issue recently.

http://www.garagejournal.com/forum/showthread.php?t=299347

And living with a hot grouchy wife for anoiuther 7 days is not going to be fun

 

[Mike007]

They claim the new valve will just clog up too.

I should also add, before this was a known issue, I ran into it on a 2 week old system. I went out, replaced the TXV and liquid line drier and the new one did not clog up. It's been a year. I believe adding the Re-new to the system is not the best way to fix the issue, but it costs the manufacturers less.

 

[sms1974]

It is legit any unit that has a Bristol scroll compressor... There is a date range for manufacturing time of the units we've seen it in both Trane / American Standard and Water Furnace geothermal equipment but I have been told it's due to Bristol's manufacturing process. The AC-renew product works like a charm in everyone so far, I do have questions about long term effects tho...

 

[Mike007]

They claim the new valve will just clog up too.

I should also add, before this was a known issue, I ran into it on a 2 week old system. I went out, replaced the TXV and liquid line drier and the new one did not clog up. It's been a year. I believe adding the Re-new to the system is not the best way to fix the issue, but it costs the manufacturers less.

Unbelievable. Talk about jinxing yourself. I posted the above and the woman who owns this system called me the next day. The new TXV after running fine for over a year is plugged up. So apparently the manufactures are correct. Replacing the valve will not be a permanent fix for this problem. So I will be putting the Re-New in this system.

 

[Mike007]

Unbelievable. Talk about jinxing yourself. I posted the above and the woman who owns this system called me the next day. The new TXV after running fine for over a year is plugged up. So apparently the manufactures are correct. Replacing the valve will not be a permanent fix for this problem. So I will be putting the Re-New in this system.

So, I put Re-New in this system today. It was running a 30* coil temp with high superheat and subcooling. I ran the system for 15 minutes as per the manufacturers instructions. There was no change. I then ran the heat for 10 minutes and then went back to cooling. After 10 minutes the coil was running 40* at 26* superheat. I will check it again in a week. It worked surprisingly fast. In this case I had a happy customer because the A/C came back quickly.