For those that think a single phase scroll can’t run backwards, just haven’t been unfortunate enough to see it. I’ve saw it multiple times and just yesterday I was in the attic and bumped the float switch with my foot and short cycled it and I could the awful sound they make from up in the attic. I think it’s more common than some realize.
Happened to me before when I tested Float switch for functionality it made a awful sound I immediately shut off the condenser then the home owner comes out and ask “how’s it going” I responded fine and flushed the drain line and fired the condenser back up and it ran like a sewing machine. it was a relief that it ran normal
@@joeshearer1247 Didn't it have a turn-on delay so it could equalize first? Mine's not a scroll but I can tell you when the power blinks out the only things I hear for the next minute or two are the blowers. I thought it was universal practice.
@@InsideOfMyOwnMind Many systems have no built-in delay, particularly older systems/thermostats. There’s also a number of electrical issues that can AFTER the delay mechanism so wouldn’t trigger it - say a float switch or other switch wired between the delay and compressor contactor (so avoid wiring switches this way if possible).
@@ludercrous I thought a float switch or moisture sensor was supposed to be wired to simply defeat a cooling call from the thermostat? Also I would think there should be some hysteresis in the sensor circuit so a random momentary reconnect would not be seen.
Good video. I’ve seen scrolls run backwards lots of times. Customer calls in and says power flickered and it stopped cooling but it’s working good now. They scroll could have run backwards, overheated, shut off, and came back on a couple hours later. I try to wire C to the thermostat and take the batteries out.
When a compressor fails for low compression, you can have situation where oil is delivered to evaporator but not enough vapor mass flow to get oil back to compressor. Besides getting insufficient oil back to lubricate compressor speeding its failure, when you install a new compressor without removing the oil flooding the evaporator, the new compressor, with good vapor mass flow rate, returns the excess evaporator oil back to the new compressor possibly giving a too much oil situation.
High suction and low head could also be an overfeeding TXV. It could also be combined problems such as high indoor airflow accompanied by an undercharged system. The only way to know for sure is to run ALL your tests first including indoor airflow measurements. I have been around along time and have never seen a tech perform indoor airflow testing on a regular basis for diagnostic purposes. Also most installers throw an ac replacement at an existing furnace and never check the indoor airflow. Alot of installer at best will set the indoor blower speed at the right cfm but never check the actual cfms incase undersized ductwork is at play. Theres so much shotty work going on out there but people get away with it because theuy get the system to run cool so homeowners are none the wiser.
I don't know about AC scrolls, but I can say that refrigeration scrolls (in my experience the ZB, ZS, and ZF from Copeland) are designed to pump down on a regular basis. It's generally not a good idea to run an outdoor refrigeration condensing unit without pump down.
1:01 - Where did you do that in MQ?!! I’m glad you mentioned inputting values into MQ. A few weeks ago I was watching a post on the HVACR Videos channel where he said he input the values off his manifold gauge set into MQ an was able to get an MQ analysis from it; but, I’ve been unable to find where in MQ to input pressures.
Excellent breakdown I'm just an ice machine technician, question a component added to a functional system to access the refrigerant circuit? Brazed on valve, check valve, king valve or pressure valve?
Compression ratio has always been the measurement of compression in the cylinder of a reciprocating engine, be it a compressor or an internal combustion engine. Couldn’t these Millennials at least have come up with something original like, “PRESSURE ratio” which is actually what it is a measurement of.
I had a 13yr old compressor that was not compressing . Scroll compressor i just put in a brand new Copeland scroll and my pressures are equalizing. There is no reversing valve in the unit. It's a gas heat Rheem unit. Any ideas on why?
HELP! I am not an HVAC tech, but my AC has been having the same problem for the past 2+ years since I've moved into the house. I've had two companies come over many times and I've spent $1,000+ and no one knows what is wrong! The latest company wants to replace the TXV at the cost of $3,000+ with no guarantee that it will fix the problem. I just feel everyone here is just guessing and I'm at the point that maybe I should just replace the system, but it's only about 5 years old. Please let me know if you can/are willing to help!
Diagnosing a low compression compressor on a 2 month old system. Iow amp draw. 2.2 compression ratio from liquid line. When i shut off unit the compressor seemed to continue rotation for a longer than normal duration. Could this be another tell of low compression?
Have a question about an AC unit that is being used to cool a server room. Would like to send you a recording of the 2 AC units. One looks completely normal, the other amperage varies from 22 to 25 amps per phase about once a minute. This is a 3 phase 208 volt system. The line set is about 150 feet long. The AC units are air cooled condensers (both are on VFD's). Both sets are I believe identical. Thx
That sounds an awful lot like a loose connection on one of the phases. Poor contact creates higher resistance which causes the other two phases to draw more current until the connection cools and the cycle repeats. Monitor line voltage going to the compressor contactor and watch for a leg that rises with respect to ground or the pair that falls when the current rises. Failing that check if the rise in current corresponds to a rise in line pressure, the VFD might be failing to track with the load.
Hey hi I watch your videos all the time here in Miami. I got exact same pressures. On Rheem split system 210 and 285 on 410 A 2 yr old RA1424 or 2 ton 14 seer Exp Valve inside Scroll compZP20k6E or 20000 but s...,.,what app are you using there. Low amps about 7 max .Any advice I was suspecting txv but not enough time to get to AH. Since condenser is on the Roof at 9 floor and AH at 1 st floor. Over 90 feet of copper lines 3 4 and 3 8 size
ratio of head to suction want pressure up enough 29 degree split you need to know outside temp indoor changes to much low suction ditrty8 my most hearounps revert to heat distribution tubes what I said to begin with 39 year HVAC 10 year instructor suction is pumping or rla kra just put something over condensed to see if high sige temp goes up absolute 14 7 psig or 0 psig ligyid line not to much discharge line and liquid line same temp no shits disagree bot pumping screw centrifugal chech valve in discharge line so scroll won't run backwards on short cycling unless discharge line check valve sticking go to the load what is outdoor ambient
With all the Lucky Goldstar compressors out there in Lennox and Carrier equipment, this is becoming way more common in scroll compressors than it used to be! We are not a Lennox or Carrier dealer, but I've found more Lucky Goldstar compressors running a low compression ratio than all other compressor failures combined in the past 3 months.
I have a trane system . 410a. My low side 158 with 17 deg SH . And my high side 290 with SC of 0.0 LLT 85 SLT 70 and outdoor temp 89 with a indoor temp of 75 . I was thinking bad compressor . The RLA on the data tag show 16 and amp meter shows 7
@@OPDrags 54 deg . The said she heard a load Redding coming from the condenser. I check the charge . And pulled the charge and recharge the to the spec . Check the txv . Thing at first it was the txv .
Your SC can’t be 0 with a LLT of 85 degrees and your hi side at 290. Your condensing temp is 94 minus 85 LLT = 9 SC What is your delta inside the house?
Sounds low if air flow is good. Factory charge doesn’t necessarily mean it covers the line set and evap. Compressor amps are good. If it’s above 16 then you’re in trouble.
Love all these videos. Great refreshers if you already know this stuff and tons of useful info if you dont. Really appreciate having these videos available to watch and rewatch.
