Carrier rtu AC not cooling

[@actechformallyyomama746]

That’s called a digital compressor. The plug you found hanging loads the compressor when energized. Which is kinda weird. Semi-hermetics energize to unload. As far as Carrier goes the first 2 digits in the model number indicate gas or electric heat. 48 is gas and 50 is electric heat. Stay safe brother.

[@hackfreehvac]

*Digital compressors* are the ones that unload 100% when the unloaded is active, lifting the upper scroll plate up and vary a duty cycle of how many seconds loaded vs loaded on an approx 15 second cycle (7 sec loaded then 7 sec unloaded then repeat... = 50% capacity for example) . This compressor here is a scroll that always pumps except when the loader plug is off, the discharge bypasses the last short section of the scroll to lower the compression (resulting in a fixed 70% capacity) and powering the loader uses the whole scroll for 100% compressiin.compression. The "digital" compressors are all or nothing when loaded vs unloaded.

[@dimpy010]

Aka scroll compressor

[@fredflintstone8048]

You have my sympathy. I've also had to study some types of diagrams for a while that were confusing and frustrating to me at first.. The longer I would study them the more they would make sense until I finally understood. I would beat up on myself because I felt I should have been able to get through that process more quickly than I did.

[@coldking8383]

Hey Bill - new to your channel . Good video. The impedance of the unloader will depend on the series -the ZPS -K4 compressors have a resistance of 330ohm . The ZPS-K5 compressor has a resistance of 1640 ( source A )or 350 ohm source B

[@domenicpurgatori7068]

I always wondered what those wires were for haha. Luckily I'll be a step ahead if I run into this same issue in the future. Keep up the good content brother.

[@jrh86]

We never stop learning, thanks for this very interesting video.

[@Thermoelectric7]

Wonder if the high supply temperature you were seeing was because it was in reheat mode trying to dehumidify. That would have greatly reduced the cooling capacity as it was already running at half capacity. Potentially pulling the reheat call would allow it to maintain temperature a little better, until the compressor is swapped.

[@tehGazdaa]

Please make a part 2, this is interesting ive never seen one either, seems like you got it, unfortunately for the customer they've probably spent a lot of $ on that unit

[@jproper]

Keeping us in business

[@rickalders]

If you look at the whole data tag you can easily tell it’s not a 4 ton, 5 ton, or 6 ton unit. Right above the two bar codes and below the Intertek logo it says “Cooling Capacity 88000”. So that makes it a 7.5 ton unit. Pause the video at 0:27 and you can plainly see it.

[@jrsmyth9761]

Misspoke I am sure, but it was a Y2 call and not a W2 call. The dotted line did not go to reheat, it went up to 8 before it "landed" at reheat. A txv takes the place of the Acutrol metering devices, so there should NOT be anything else to meter the refrigerant past the txv. I am not familiar with that unit specifically, but I do not recall ever seeing a LL solenoid in an RTU. The look of that install of the LL solenoid screams retrofit, kind of like the heat block on the txv.

[@FrostHVAC]

It's normal for these carriers, I've seen em on there, I figure it to be the "second stage" lol

[@hackfreehvac]

48 means gas pack. The capacity is in tens of thousand BTU so a 48HCD06 would = 60,000 btu which = 5 tons. *The plug on the back of the compressor is the LOADED plug for the 2 stage scroll* So with that unplugged you were down to 70% total rated capa ity. With the supply on high speed with Y2 call you'd have horrible split temp

[@ZRock7771]

It's confusing but with carrier they have a number system for capacity that has nothing to do with BTUs, although it is close oddly enough. It goes somthing like this: Carrier Tons (In Model#) 48TCFD[--] 04 - 3tons 05 - 4tons 06 - 5tons 07 - 6tons 08 - 7.5tons 09 - 8.5tons 11 - 10tons (12 EER) 12 - 10tons (11.5 EER) 14 - 12.5tons 16 - 15tons 24 - 20tons 28 - 25ton 34 - 30ton Edit: I have all the major RTU brands in a note on my phone with how to tell the tonnage based off the model# if anyone's interested.

[@hackfreehvac]

@@ZRock7771 Actually the model number has everything to do with BTU's but just each number counts as 10,000 So a size 03 is 30,000, 04 is 40,000, 05 is 50,000, 06 is 60,000 etc. And they just do all the sizing in 10,000 increments rather than the usual residential increments of 2 ton, 2.5 ton, 3 ton, 3.5 ton etc... It is different. But again. Carrier was pretty much the first mass produced Air Conditioner so I guess they do what they want. LOL

[@ZRock7771]

@hackfreehvac so why after 5 tons does the BTUs and tons not match? A 25ton carrier is 28, but 25tons is 300,000 BTUs not 280,000?

[@hackfreehvac]

@ZRock7771 A ton is a unit of measurement that simply means 12,000 BTUs (like 1 yard = 3 feet). The Carrier commercial numbers indicate how many BTUs in 10,000 btu increments. 30,000 40,000 50,000 60,000 70,000 80,000 90,000 100,000 110,000 120,000 etc. The size on the label is just an abbreviation. So a 03 =30,000 and a size 06 = 60,000 etc. All in btus. The raw unit of measurement. When comparing the two separate units of measure, it just so happens that a size 60,000 is exactly 5 tons (12,000 time 5) and a 120,000 is exactly 10 tons (12,000 time 10).

[@ZRock7771]

@@hackfreehvac I'm still struggling to understand it with the bigger size units, but just wanted to say I really enjoy your videos man. Keep up the drone footage! That amazon warehouse with 300 carrier RTUs was crazy.

[@ericgrooms6645]

Ive never seen that plug before. My first thought was crankcase heater, but yeah.. thats how the trade is, theres sooo many things we can learn.

[@mc-sp8zr]

Carrier tonnage is in the numbers after the "48TC...", so in this case the "08" that follows. I believe that's a 7½ ton unit you've got there. About 8 years ago I ran into a similar problem that really stumped me. We had a Carrier unit with an intermittent low voltage short. Cooling would run in test mode, but after a few minutes it would cut out. Couldn't find any immediate clues.The compressor with 2 thin blue wires coming off the back which I had never seen before. What I thought was some kind of thermal overload was actually a stage 2 solenoid. Apparently it had a short, and we had to replace the compressor. Never saw another one since.

[@austrianpainterinhiding88]

That's very interesting, thanks for sharing.

[@davidturney2975]

I ran into a fun one this week. Had a liebert unit that wouldn't cool and the hot gas bypass was staying engaged and the liquid line solenoid valve wasnt opening. It had me confused for a bit. The HGB staying open because the LLSV wasn't opening made sense to me. After some thinking and digging and tracing I found that the solenoid coils had been switched by someone for whatever reason. I was dumbfounded by that. The most confusing part was I was getting voltage to the LLSV coil the whole time but that valve wasn't opening.

[@stevencossaboon3237]

Nice work Bill.

[@fredflintstone8048]

The resistance of the loader would not be that unusual if the voltage that feeds it is AC due to inductive reactance. I wasn't really sure if you were saying there were diodes in the circuit and I'm not able to read the schematic on the display to tell. If there is one or more diodes in that circuite then it's going to be a DC voltage. With a DC voltage supply 0.4 ohms is pretty low.

[@wayneschneyer8699]

Did you ohm out the unloaded terminals in the compressor? Should have had like 10-14 ohms for that coil. If low (5) ohms the coil is internally shorted. ( comp change out) OR if the terminals are grounded too. Point is, now your SURE that is the issue.

[@chrissipple1018]

Your second stage for cool sends 24 dc to the plug and that energizes the second stage cooling.

[@michaelbuckley3808]

What did you find on the second RTU? Will that be a third video?

[@EkremOncirak]

Isn't that a solenoid for mechanical 1-2 stage modulation?

[@markhoffmann5941]

Did you check the evap. coils entering air temperature when you recorded the S/A leaving air temp @ 70 degrees F.

[@hrdworkin7633]

I've never seen that either. I wonder if more information available on the Emerson site for the compressor? just a thought.

[@lakeshvac]

Second stage plug. It uses 24 volts ac to the plug and the plug converts to dc . To bring the 2nd stage of the compressor in

[@Jeff-Lawrence]

Curious, why would W2 kick on? Is that the signal for the unloaded?

[@HVACR559]

70 degrees is normal supply air if the unit is in de-humidification mode. That solenoid allows hot gas to go to the reheat coil. There are also two other solenoids in the blower compartment to control the refrigrant flow through the reheat coil to hold the return and supply tempature the same. Essentially loading the space with the reheat coil so you can keep running air through the cooling coil for hours on end. A digital compressor! The unloader allows the scroll plates to separate in a 15 second interval, so 7 seconds off, 7 seconds on would be 50% duty cycle. 1) This is better than an inverter driven compressor because the refrigerant velocity doesn't change in the on cycle. VFD running a compressor slower speeds causes the suction line to be oversized and that can cause oil return problems. 2) There's no expensive VFD in the mix. Sometimes you can hear the compressor making a clicking and tone change as the compressor engages and disengages, motor speed doesn't change. They sound broken when working properly.

[@MariosACandRefrigeration]

the question is,what caused the unloader to fry ?

[@roqueherrera8471]

I like that no blinking

[@chrissipple1018]

Copeland used 2 different manufactures for the compressor solenoid unloader and each has a different ohm readings.

[@LadariusCapersOfficial]

2:45 that’s the connection plug to the compressor know wonder why the unit wasn’t working 🎉

[@SupermarketRefrigeration]

The Copeland Mobile and AE Bulletins apps will tell you everything you could ever want to know about Copeland compressors.

[@randytorboli]

Great video Bill

[@shadowbanned69]

Turns from a 2 ton to a 4 ton with only 1 compressor...I thought it was a humidification thing but that opens the unloader???? Wow that's a different way to do it...only carrier

[@shadowbanned69]

Another way for the customer to save money but actually cost some more in the end That's a really stupid idea

[@RalphMercuroMusic]

Two stage scrolls have been out for quite a while... Copeland calls them The Ultratech

[@shadowbanned69]

@@RalphMercuroMusic didn't know that...I've seen mostly refrigeration types for walk ins and freezer comps with the injection circuit on top....but never a two stage like that...thanks for the info

[@EverythingHVACR]

Nice job, Bill!

[@jacobfoxworth]

Carrier has a weird model number nomenclature. The numbers after the letter string are the tonnage, and it's always one size less than the number. Yours said 8 so it's 7.5 ton I believe. Crazy carrier always gotta be different. 😂

[@hackfreehvac]

It is in 10's of thousands so an 05= 50,000 and. 06= 60,000 etc. So the 06 is a 5 ton, 12 is a 10 ton, 24 is a 20 ton etc as they fall on the even numbers for btu/12,000 ratings and all the others are oddball in between sizes.😂 But as far as sales are concerned they sell a 04 as a 3 ton, 05 as a 4 ton, 06 as a 5 ton, 07 as a 6 ton, 08 as a big 7 ton etc as the numbers drift slightly.. Can be fun

[@jacobfoxworth]

@hackfreehvac lol did not know that. I knew they were up to something. The engineers at carrier must've been as high as a kite the day they came up with that complicated stuff. 🤣🤣

[@hackfreehvac]

@@jacobfoxworth Yeah I still don't know why they did that on the commercial equipment. But you get used to it. Another thing they do differently is their heat pumps use Y for cool and W for heat (conventional rather than direct reversing valve control) so when a tech is installing a new digital t stat and selects " heat pump" in the stat, it wont work right. You must set the stat for "conventional" or electric heat etc. Engineers are still laughing!!!

[@jacobfoxworth]

@hackfreehvac holy crap. No shit? Jeez, ill definitely have to remember that one. We don't have many heat pumps in my area so that's definitely one to remember in case I ever come across one.

[@hvacmisadventures]

@@hackfreehvachahaha only took me 2 call backs to the same place to figure that one out as a green tech. Never forgot it since 😅

[@HVACRNorth]

🤘👍

[@Techniclay]

“Makes my brain hurt” ha! SIR what it all boils down to is. . Well . . Fucken things sucks 😊 stay safe out their!

[@SickaMorStyle]

I’m somewhat sure that solenoid is a for the dehumidification reheatcoil.

[@t.a.servicehvact.a.service3189]

nice job

[@electroshed]

If only the unloader, or more of a half-unloader would have failed to 2stage eg power supplied to it = single stage, you could have worked around the fault by cycling the compressor instead

[@davidwalz2283]

It has a humidimizer in it.

[@winkhvac62]

Never see a extra plug like that.

[@kevonslims7269]

Biggest problem with the Air conditioning industry, they don’t give any DC control values on the schematic.

[@blakeshull9316]

No that is not a digital. That is a 2-stage compressor receives an AC signal from the board, and gets converted to DC buy a rectifier within that plug. Make sure that you have 24-volt AC off of the board. Then check that cell annoyed on the compressor itself. If the solenoid is good and voltage from the board is right, replace that plug. If the solenoid does not check out, replace the compressor.

[@blakeshull9316]

Since you plugged in the rectifier plug, and had a bad loader solenoid, it may be a good idea to replace the rectifier plug as well as the compressor. I have had them smoke the rectifier because of this.

[@DanielHernandez-tp2tm]

Two stage compressor.

[@johnrider7826]

you really need to go back to working at Mcdonald's, at best a helper.

[@joshuaricks7730]

How long you been doing HVAC

[@johnrider7826]

@@joshuaricks7730 38 years

[@luisortiz590]

So after all that time in the field and experience, instead of offering advice to another brother you decide to bring him down. 👏 we all at some point or another have encountered a system that was new to us and it involved a little time or advice to get acquainted to it. Good day to you sir. Be a blessing and not a curse we already have enough of that in this upside down world of ours

[@joshuaricks7730]

It’s people like you that bring this trade down. Glad to hear you’re close to retiring.

[@joshuaricks7730]

I work for Trane and still run into units that are new that I haven’t seen and I struggle with.