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View Full Version : 2 years old Puron system failed.



romac
22-08-2007, 05:23 AM
Hi everyone.
My friend has a home with only 2 years old 3-4 tons split unit Carrier Puron with 410A in it. It's completely new including ducts and so on......
He didn't use the AC unit very much since he lives somewhere else and comes once a while to check for bugs. He maybe run the unit about 5-10 times.
About 3 weeks ago it was still running fine till 2 weeks ago he couldn't cool the home more than 84F.
Warranty for the unit was only 1 year.
I am licensed but it's a first time I am facing R410A.
I am aware of some issues about this refrigerant but still need some advice. I don't have pressure gouges for this system yet but I went to do first check up. Both fans are spinning fine. When the unit starts the low side pipe on the condensing unit gets coldish but after short time it's about 90F. I forgot thermometer so I am just guessing but have to go there anyway soon. Hi side tubing at the unit is roughly about 105-110F. I done bubble leak tests at all connections and sniff test as well with no results. When I was removing high side shrader valve plastic cap, little pressure escaped. I put it back and after while I removed it again with same little pressure escape. I bubbled it but no leak visible. The only thing I can think of is that the plastic cap reaches when seated at the valve stem and slightly pushes the valve stem but inside the plastic cap is in the center at the end small dip so it shouldn't be touching especially when there is also the oring so I am having little mystery with this. Compressor's rated max amps are 18.6amps and I am reading 14.5amps at work. Air filter is still new and never had a chance to get dirty. Ceiling registers are pretty high so I have to get long ladder to reach it but what I was able to reach in a hallway it was about 70-75F. I am going to check tomorrow at the attic for blockage at the evaporator. All ducts are round and not collapsed but something is really wrong with this virgin infant.
Thanks.

dkemper
22-08-2007, 05:31 PM
First guess is it's low on refrigerant but I suggest getting a set of 410a gauges and checking the system for both pressures and temperatures before making any further diagnosis in that direction.


Check airflow across the condenser. If any of the local insect life have nested in the often unused condenser, it might simply need a good cleaning

paul_h
22-08-2007, 07:49 PM
If everything is running, it sounds short of refrigerant.
It was very common here when r410a first came out, as you have to do the install properly for r410a not to leak. Most installers were slack, untrained and did them as bad as they did the r22 units which somehow didn't leak due to the lower pressures.
It sucks being only a one year warranty, here it's five years. I've heard from people in the USA that most of the r410a units had 3-5 year warranty to try get people to buy them over r22 units, so I'm surprised at the one year warranty your friend has.
edit:
Without having a set of gauges, look around the flare joins for signs of oil, or maybe pump the system down, shut the valves and crack open the flares to inspect. Use your own judgement on whether they're bad enough to leak at 3500kpa pressure as far as roughness and burrs on the thread and quality of copper and welds. Possibly that would answer your questions on whether the fault is a suspected refrigerant leak.

romac
23-08-2007, 02:36 AM
Thanks for reply. I bought today the manifold for Puron and tomorrow my plan is to invade the attic to check the evap. before it gets to hot out there and later to check those pressures and temperatures. The condenser looks clean except bit of sand on the bottom of those fins from a rain but really just a bit. I'll update my findings as soon I know more. Thanks again.

romac
23-08-2007, 04:47 PM
Hi, I am back.
Here are the measurements I took this morning.
Outer temperature: 80F
Inside temperature: 92F
Unit not running: L-240psi, H-220psi
Unit running: L-105-110psi, H-300psi
Temperature from ceiling registers: 65F
After 30 minutes or running the unit the Low side was 115psi and high side 310psi. The low side pipe at service valves was roughly about 80-85F, I was using a laser to measure the temperature so it might not be exact number but the pipe should be sweating since we have humid days and much colder by touch.
I didn't find any blockages in ducts and the evaporator is clean as well. The house it self is 2 years old, windows with insulated glass and so on.....
So we might all agree on some type of leak I guess but I couldn't trace any unless in the attic where I couldn't get due to lumber structure is hiding some connection since the piping is more than 15' long.
I red about leaks of R410A and in case of leaks the ***** should be removed since part of the 2 chemical components escapes faster than the other one so adding just more refrigerant would make the unit not work correctly, right? Can some one give me an advice on this one? Thanks.

paul_h
23-08-2007, 06:48 PM
You don't want to be adding more refrigerant anyway if you suspect a leak. r410a leaks really easily, I've even had systems up to 2500kpa pressure with nitrogen and not been able to detect them with soapy water.
I don't know your equipment or experience, but if it's flared, at least check them and if they look rough or burred re-do the flares. If you have a decent electronic leak detector (even the cheap ebay ones do the job from personal experience) go over as much as you can and check for leaks.
From personal experience, if the leak is inside the units, most of the time you'll have some oil in the place you have the leak, so feel the pipes and base for oil.
If you don't have and electronic leak detector, reclaim fill with r22 and nitrogen and check with a gas halide detector for leak before evac and recharge.
From what I've heard, r410a is even more expensive over in the U.S. than it is here, and you don't want to be recharging it every year from a labour perspective anyway, so be as thorough as you can.