Freus problem what to do next

[vance500]

Oh wise men of the alt.hvac newsgroup

Moved Freus unit (4 + 2) from a large house the owner could not afford to a smaller house he just bought that had a York 4 ton condenser. Swapped the 4 ton condensers and added a 2 to the old larger house. The start up on the 4 and 2 ton air cooled condensers that had been moved to the old house went great. But the 4 + 2 Freus won't work. So here is the situation.

Pumped down both units to save most of the Freon Closed the liquid and suction back seating valves Moves the unit to the other house and reconnected the refrigerant lines and installed liquid line drier using nitrogen Put a vacuum on the system And then weighed in a half pound of refrigerant and opened the valves Got ready to do a sub cool on start up and then F**K - the unit won't work

Here is what I have

Freus 4 + 2 unit with scroll compressors The four ton compressor is a Copeland Scroll ZR40K3 PFV 230 RLA 12.6 LRA 104.0 The second circuit (the 2 ton) is not used and the LS sealed The Freus units condenser fan and water circulation pump always get power from the first circuit which in this case is the four ton so all controls ok. Equilibrium pressure is 125 Lbs but when the contactor closes the running amperage rapidly goes from 12 to 15 to 23 amps and higher them the compressor starts bypassing - this happens in 2- 3 seconds. During the 2-3 seconds the suction pressure drops to about 80 before the compressor starts to bypass and the liquid line pressure stays the same or drops maybe 5 lbs. The suction line does not cool and the liquid line does not heat but the refrigerant line between the compressor and the condenser gets hot in those few seconds. I checked the ports to make sure they were open, verified the capacitor mF and looked for any other things I may have done wrong. I must also admit that originally I thought maybe the parker port was stuck so I installed a piercing valve between the compressor and the port on the liquid line to see if there was a pressure difference - what a waste of time. Never experienced this before - what am I missing?

[what a maroon]

Check your line voltage and compressor windings. Make sure that the compressor that you disabled is not trying to fire when it shouldn't.

[Stormin Mormon]

It's really easy to block shut a liquid line with solder. I've taken to soldering all fitting horizontal, if at all possible. Sounds like you have a blockage of the liquid line. My old boss used to call it "solder balling" the line.

[Stormin Mormon]

Oh, forgot to answer your question. "What to do next". Follow the liquid line, and replace anything with a solder or braze connection. Filter dryer, and then pull apart the connection where the liquid line goes into the evaporator. Look for signs of liquid line blocked by solder or braze. When you put everything back together, make sure the lines are as horizontal as possible, so excess bonding metal drips out instead of clogging the line. There is a small chance you have a defective filter drier, either in the condensing unit case, or maybe in the line between the condensor and the evaporator. Small chance also that you negelcted to open the liquid line service valve. You may also have a clogged orifice "piston" in the evaporator. Or bad TXV.

[vance500]

The second circuit is not connected to any line or low voltage windings - there is no power going to the contactor. Only the first circuit is connected single phase 230 and stat wires. All refrigerant lines and electrical line are connected to the proper circuit.

Also, the line set were cut about 4 feet from the valves. I just added a coupling and liquid line filter to reconnect to the other system. I've never blocked a line with too much silfoss

Yes, I have seen amperage climb on blocked systems; however, the pressure also goes up on the liquid line side until the compressor starts to bypass at about 400 PSI with blocked caps or if locked rotor it happens instantly. But this is different and like I stated above in original post

please let know if you need any other information

[Stormin Mormon]

You're not telling us what was happening on the high side. What were the pressures? Did it run up to 400 before the safety valve started to recirc?

[vance500]

Maybe I wasn't clear. This is what happens when the condenser is off both high and low pressures are at 150 lbs. When the contactor pulls in the high side stays about the same 150 lbs or it may drop slightly 4 or 5 lbs. This is what is strange. Normally it takes about one or two minutes for the pressure to increase to the point that the bypass opens in the compressor. But the compressor starts bypassing 2 - 3 seconds after start up. The suction side drops about 25 -30 lbs before the compressor starts bypassing. When this first happened I thought the liquid line valve was stuck even though I opened with my Allen key. To check this I installed a piercing valve on the liquid line on the compressor side of the back seating valve thinking the pressure would be much higher if the valve was stuck. After connecting my gauges to the new port I found the pressure was the same. BTW if I leave for a day and let the unit sit it still bypasses on the first try the next day in 2-3 seconds. Thanks, Vance

[Steve]

Stormin, maybe someday when you have a clue.....

2 things to do.... first, when you attempt to start the system, check the filter/dryer... whats the delta T across the filter/dryer?? 2nd, pump down the entire system, pull a proper vacuum(400microns) and weigh in a new refrigerant charge.

[Stormin Mormon]

I'm thinking some kind of blockage in the liquid line. What you're describing, there is some kind of block after the compressor, but before the two valves (one of which you installed). I've seen some condensing units use a filter drier inside the unit. Which would be after the compressor but before the service valve for the high side. It's very possible that the internal filter drier is blocked some how.

[Stormin Mormon]

Ah, you're just jealous.

[Old and Grunpy]

Does this unit have head master or head pressure control if it does. the head master have three lines to it hot gas from compressor which also goes to condenser other line goes to liquid line of condenser which is outlet of condenser and third line goes to receiver or to TXV. these valves some time after you pull vacuum on them do hang up in close position, take hammer and give it good bang from side do not hit upper head part, ones it had loose up it should work perfect no need to change. tony

[Old and Grunpy]

you did not fill line full of solder by chance

Normally it takes about one or two minutes for the

[vance500]

All the ideas so far sound good but I double and even triple checked most of them:

Too much Silfoss, probably not because I cut the existing lines about

4 feet from the condenser then used a liquid line dryer to reconnect the high side and a coupling for the low side. Also, when the compressor starts the high side doesn't go up - it just stays where is started at 150 psi. Then 2 seconds later the bypass opens for about 2 or 3 seconds and then closes for a couple of seconds. After a couple more seconds of the compressor running the bypass opens up again and the pattern repeats. So, if the liquid line was blocked by my brazing my head pressure would increase rapidly and its not.

As for Old and Grumpy's post, that might be a possibility but I would have to look at the condenser more closely. The only thing I saw was a strainer but I could be wrong. All the other things have been checked and it almost act like a 3 phase condenser out of phase with the extra problem of the bypass opening and closing.

Are any of you guys familiar with Freus Condensers and package units. The condenser coil is water and air cooled. Their package units used to be manufactured from York package units. And all their compressors are Scrolls. This is the first time I have encountered anything like this.

One more thing the evaporator coil is a Summit 4 ton multi-position with txv and all the equipment is about 2 years old.

[Zyp]

Pressure relief valves that by-pass the cylinders in the compressors work on a pressure differential. If the compressor meets that differential [compression ratio] the valve opens. If that occurs before your gauges respond.... well you might not see a drastic rise. [I'm surmising here.] I'd be interested to know how you know for sure you've closed off the correct liquid line. If there's one coil with two circuits, it could be difficult to tell.