Skeptical A/C Issue

[toocoolforschool]

I plugged your invoice data into my Android phone app "HVAC Buddy", assuming a 67 degree wet bulb for that missing data above. It returned a verdict of "high superheat" and stated possible causes as "undercharge (leak) or restriction".

So there you go. An app on a smart phone reached the same conclusion I and other techs here have. How 'bout that?

I figure since they are adding refer it must be leaking causing the coil to freeze. Time for a proper leak check, then possibly replacing leaky part (evap coil) not repairing-- Open wallet. AGAIN.

[beenthere]

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[moparman915]

I plugged your invoice data into my Android phone app "HVAC Buddy", assuming a 67 degree wet bulb for that missing data above. It returned a verdict of "high superheat" and stated possible causes as "undercharge (leak) or restriction".

So there you go. An app on a smart phone reached the same conclusion I and other techs here have. How 'bout that?

Good info. He did state the there was a restriction somewhere in the system. He OHM'd the motor/ windings in the motor and got a 1000 or something like that. Electrically, the motor checks out, he says.

Also, the fan just started making a humming noise when running with no A/C and pushing just ambient air. Could that be the source of the problem?

[moparman915]

I figure since they are adding refer it must be leaking causing the coil to freeze. Time for a proper leak check, then possibly replacing leaky part (evap coil) not repairing-- Open wallet. AGAIN.

I just received some good news on the Evap Coil/ Condenser... They are still under warranty by Nordyne. By evacuating the system to 500 microns, would that have constituted a leak check? What does "evac to 500 microns" mean anyways?

[moparman915]

I inquired about the piston or fixed orifice to the contractor and he stated that it was neither of those because they have been outlawed in California for a number of years. Which begs the question, what does my unit have? If the piston/fixed orifice was outlawed and, according to his email response to me from the distributor, my unit does not have a TXV, what is the device used in my unit?

I am starting to get the feeling that I am being fooled. I asked again about the metering device and he said that he could not tell what my system had without opening up the evaporator case and that he "assumed" the system was a TXV system because of the way it was behaving.

I don't like pay professionals for assumptions, I need results...

[moparman915]

If you still want Contractor #3 involved, tell him you want to know what type of metering device you have (piston or TXV), and that you want it checked for trash. If he opens it up and finds none, tell him you want a new liquid line drier installed just upstream from the piston or TXV, if that's possible. If he agrees to do this, he will need to remove any old driers already in the system. This is important. Truth is, he should have already done things like this instead of you finding out about it on an internet forum. I may be barking up the wrong tree as it is, but I'm not inclined that direction at the moment.

I asked about the metering device and he stated he would have to open up the evaporator coil to find out the metering device my system has. He said that sometimes the condenser will say if the system is a TXV system, cap tube or whatever device the system has.

I asked him to clean out the metering device, based on your post earlier in this thread. He said that he has never had someone ask him to do that before and that it would only be a 50/50 shot at working. He said that is there was any sediment in the line that it would have been cleaned out when he did the evac, purge and refill. What do you think?

[moparman915]

If it didnt come with a txv it most likely has a piston or fixed orfice. If it is clogged it can cause the low side pressure to drop and high side to rise, and if a tech just looks at the low side pressure and doesnt do a decent diagnosis he will assume it is low on refrigerant. This is only an assumption on my part. Unless the system lost all of its charge at some point I dont not understand how air could have compromised the system, unless when he evacuated it (I am assuming the refrigerant that was still in the system was either pumped down into the condenser or they recovered it into a clean empty tank) he accidently broke the vacuum with air before recharging system. I dont see a capacitor being an issue in this situation. Like has been said looks like every one is shooting from the hip and #3 wants to sell you a new system. I dont think a 7-8 yr old system needs to be replaced, just fixed as its major parts most likely still under warranty. I hope for the best.

I asked again about the capacitor and he said that it was bad becuase it was rated at 5% and it was reading at 4.7%.. He changed it because it needed to be changed anyways...

I am not getting a good vibe from contractor #3, especially after he changed the capacitor and it really didn't fix anything. I am hesitant to get ANOTHER contractor because that is too many people working on my A/C. I am getting the feeling that they are taking advantage of their position and scamming their customers.

[moparman915]

On my telephone conversation with him today, he said that he didn't like what was going on with my system because he can't figure it out and it make him look bad. I told him that his credibility took a hit when he changed out the capacitor and it didn't fix anything. Seems like he is just taking shots in the dark, as its been said in this thread.

[toocoolforschool]

Hey a 50 50 shot is better than what you have been getting. Seriously You have got to find someone that can figure out whats going on. Now your fan motor is not operating correctly. I just don't get it. Humming fan motor???? You mean they haven't checked the operation of the fan motor with a symptom of freezing coils??? Also it is possible to determine metering device by checking pressures and tempuratures at condenser.

[Shophound]

I asked about the metering device and he stated he would have to open up the evaporator coil to find out the metering device my system has. He said that sometimes the condenser will say if the system is a TXV system, cap tube or whatever device the system has.

I asked him to clean out the metering device, based on your post earlier in this thread. He said that he has never had someone ask him to do that before and that it would only be a 50/50 shot at working. He said that is there was any sediment in the line that it would have been cleaned out when he did the evac, purge and refill. What do you think?

Well, I said Contractor #3 showed promise, but that may be dimming a bit.

A seasoned tech can often tell what type of metering device is on a system without actually going to look for it. In the olden days, if a TXV was on the system, the single phase compressor had a start-assist kit on it. Nowadays, with scrolls, not always the case. However, when measuring a system, if it has a TXV on it, the superheat will remain pretty steady as the heat load on the evaporator changes and the condenser head pressure changes, whereas with a piston, the superheat will change with evaporator load and condenser head pressure. If a TXV fails, it often fails closed, as the only opening pressure on a TXV is the bulb pressure. A failed TXV will typically starve the evaporator of refrigerant, resulting in very high superheat, low suction pressure, and low head pressure.

Of course, whether a system has a TXV or a piston metering device on it, if there is trash/debris in either device, it can act like what Contractor #3 described, where everything seemed fine and suddenly it was like someone closed down on a valve. A metering device of whichever type is the smallest passage in the system, so any trash that freely circulates in the system WILL get hung up here, if it is large enough.

Contractor #3 needs to educate himself on what an evacuation, purge, and refill does to a system. Will it remove solid debris? On the purge phase, maybe some. Even then, only if he's doing a purge a certain way. But that is not how things are done right. To catch debris, you install a liquid line drier ANY TIME THE SYSTEM HAS BEEN OPEN TO THE ATMOSPHERE. And you flow nitrogen while brazing in that new liquid line drier, and for any other work done on the circuit that requires brazing. The liquid line drier serves two functions; it filters the system, and it catches any remaining moisture that could not be removed by a vacuum pump.

Evacuating a system does not remove solid debris. Evacuation is for removing moisture and air (non-condensibles). Purging is mainly done with nitrogen and a product to rid the system of oil...either because oil is logged up somewhere in the system, or the tech is converting the system from mineral oil to POE oil. Purging is NOT done to get moisture and air out of the system, and it won't remove all of the solid contaminants.

[moparman915]

I think that I am going to go with a 4th contractor. He has been in the industry for 18 years and comes recommended from a property manager friend that has lived in the area for over 40 years. He will be at the property tomorrow, so Ill post what he finds out.

Thanks for all the inputs thus far. You guys are really great!

[moparman915]

How would debris get into the system to begin with?

[toocoolforschool]

How would debris get into the system to begin with?

Poor initial workmanship. Deteriating compressor windings. Air and nc causing sludge and acid.