Any Ac experts out there?

dirtyho1968

dirtyho1968

Well-Known Member
Ok, so I have a 4 ton Excel Stealth AC unit that has been running fine for a few years. All of a sudden the compressor stopped working. I ordered a new compressor box and my unit ran for a day before the new compressor heated up again and stopped working.. I changed the motor in the condenser and that seems to be working as well. I even changed the TX valve inside the air handler and put in a orifice valve which is what the company switched to now. The suction line pressure is way to high and the liquid line reads at about 150 which is normal (150-200) which is what I'm told. I've emptied the charge and vacuumed the pressure out to -30 on the manifold gage. I got a scale to properly fill it to the recommended 7.73 lbs of R-22 into the liquid line. Still it will start off at 50psi and slowly work it's way up in the suction line. The recommended pressure is 60-65. It just keeps climbing till it hits about 100psi and then I'm assuming the internal overload on the compressor is shutting it down.

Shit is driving me nuts! Anyone have any knowledge of ac units?
 
RyanTheRhino

RyanTheRhino

Well-Known Member
Have you checked for a clog in the intake line?.. The liquid level would show up normal but the pressure would climb. I don't know how that would get a clog though. Its a closed system under pressure so you know its air tight & debris cant get in. The only thing I can imagine is using a cheapo refrigerant with impurities?

You know how to discharge that safely right. Kinda dangerous stuff you are playing with there. To bad you just put some more r-22 in it or I would say try flushing out the line.
 
RyanTheRhino

RyanTheRhino

Well-Known Member
Here is what I found with a quick search

Taken from the HVAC fourm
"a motor burnout is a motor burnout...nothing special about a screw chiller electrical motor. there are a few differences from a "small" compressor to a "big" compressor, like starting methods, etc. but the same things can cause electrical motor burnouts are the same...

locked up rotor, low voltage, TOO MANY STARTS, lack of oil, improper starting (bad contactors, missing electrical legs, etc), NON-APPROVED OIL OR "POTIONS", contaminants (moisture, metal particulates, etc.), low suction pressure (low charge, low evap temp)..."


HMM you said high pressure let me keep looking
[video=youtube;dnbtTYDLd1Q]http://www.youtube.com/watch?feature=player_detailpage&v=dnbtTYDLd1Q[/video]
 
dirtyho1968

dirtyho1968

Well-Known Member
RyanTheRhino said:
Have you checked for a clog in the intake line?.. The liquid level would show up normal but the pressure would climb. I don't know how that would get a clog though. Its a closed system under pressure so you know its air tight & debris cant get in. The only thing I can imagine is using a cheapo refrigerant with impurities?

You know how to discharge that safely right. Kinda dangerous stuff you are playing with there. To bad you just put some more r-22 in it or I would say try flushing out the line.
Click to expand...
Yeah my good friend who's been in the industry for 25+ yrs has been helping me. Plus I've been on the phone with the tech for numerous hours. They are both baffled. He also said he doesn't know how the liquid line would get clogged either.
My friend had a theory about the suction line ,it came from the company in a 15 ft coil or around that long,. The liquid line is super long too and just coiled up on the floor in the corner. No kinks in the lines. Anyway my friend thought that maybe the oil from the compressor was getting trapped in all the extra line coiled up but the tech said that there is plenty of pressure so that would be highly unlikely. But we ended up cutting and shortening it (suction line) to the proper length we need and got rid of tall the extra piping. The way these units come are with screw-on fittings to make it easy for someone to put it together. I dunno I'm stumped. I'm having them send me a new condenser with the compressor in the same housing. I pray it works. But in the meantime I would like to get this thing fixed so I have a back up. I'll probably end up shipping it back to the company and let them deal with this 3 week head ache. Seriously fucked up my timing.
 
dirtyho1968

dirtyho1968

Well-Known Member
RyanTheRhino said:
Here is what I found with a quick search

Taken from the HVAC fourm
"a motor burnout is a motor burnout...nothing special about a screw chiller electrical motor. there are a few differences from a "small" compressor to a "big" compressor, like starting methods, etc. but the same things can cause electrical motor burnouts are the same...

locked up rotor, low voltage, TOO MANY STARTS, lack of oil, improper starting (bad contactors, missing electrical legs, etc), NON-APPROVED OIL OR "POTIONS", contaminants (moisture, metal particulates, etc.), low suction pressure (low charge, low evap temp)..."


HMM you said high pressure let me keep looking
[video=youtube;dnbtTYDLd1Q]http://www.youtube.com/watch?feature=player_detailpage&v=dnbtTYDLd1Q[/video]
Click to expand...
That's what's baffling. The liquid line is reading at 150 so that's def not over charged yet the suction line just keeps building up pressure till the condenser heats up and eventually the internal overlaod just shut off and I have to wait a few hrs for it to cool down to try it again.
 
RyanTheRhino

RyanTheRhino

Well-Known Member
You know how by decreasing the diameter the pressure should drop, containments would be like cholesterol on an artery. If there is an almost complete clog then it could just back up compleatly increasing pressure as you say it does.

However if the output is clogged it could be increasing the flow of the refrigerant not giving enough time for the heat exchange to happen.

Either way since you said you replaced almost every important item i still thinks it could be a clog.
 
cannabineer

cannabineer

Ursus marijanus
I really want to know how this one turns out. Dirtyho's OP is "I've checked everything that it could be, and that's not it, and it's still happening". Dang. Maybe it's haunted. Ghosts need to, uhh, chill. cn
 
RyanTheRhino

RyanTheRhino

Well-Known Member
mydixiewrecked said:
dirty evap coil, fan is running backwards or to slow, dirty filter.
Click to expand...
Those compresses cant compress liquid so it may have to do with heat exchange now that he mentioned this


[video=youtube;uMdqwllMeOY]http://www.youtube.com/watch?feature=player_detailpage&v=uMdqwllMeOY[/video]
 
dirtyho1968

dirtyho1968

Well-Known Member
Naw, we cleaned out the coils. Shot that shit up with a medium pressure hose and cleaned it with a soft brush, used some fin cleaner...
Also that would most likely just cause the lines to freeze up right? Not enough airflow...
Gonna ask my buddy tonight to help me flush the lines. Tried everything else, why not?
I'll let ya know what happens.

CN-I ain't fraid of no ghosts, just cops.
 
cannabineer

cannabineer

Ursus marijanus
dirtyho1968 said:
Naw, we cleaned out the coils. Shot that shit up with a medium pressure hose and cleaned it with a soft brush. Also that would most likely just cause the lines to freeze up right? Not enough airflow...
Gonna ask my buddy tonight to help me flush the lines. Tried everything else, why not?
I'll let ya know what happens.

CN-I ain't fraid of no ghosts, just cops.
Click to expand...
I don't think your AC has cops. Symptoms are wrong, except the buildup of heat maybe. cn
 
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