HVAC Copeland Compressor/Bad Valves

Pump down on two condensing units as the equipment has been sold.
Found the right hand unit to have a poorly pumping compressor which is likely due to bad suction valves. The system dates from the mid 90's so has run a lot of hours, though i suspect poor installation and maintenance practices in its early life are factors in the failure.

[@JamesPettinato]

Low temp compressors don't usually pump down into a deep vaccum. If you close the liquid valve leaving the reciever tank, pump the system down until it shuts off on the pressure control, then put your hand on the compressor suction valve, if the valve plate reads are leaking you will feel the hot gas coming back through the compressor into the suction line.

[@heavydiesel]

The ones we get here are made in France under licence so i hope they keep their quality. I noticed they have recently started selling semi hermetic compressors and i was planning to give them a try!

[@heavydiesel]

Thanks! Shame the guy has retired and sold his systems, looks like i've missed out on a compressor change! :-p

[@heavydiesel]

Thanks James, this one wouldn't get below 5 psi, i'd expect it to pull at least 14"hg within 30seconds with the suction valve shut off.
I think if the suction reeds are bad it won't pump well but also won't bleed back across but if its discharge reeds it won't pump and will bleed back across giving a warming effect on the suction line you describe.
When the previous comp failed here i cut it open, think parts of the suction reed got wedged under the discharge valve! Have avid somewhere of it.

[@heavydiesel]

Thanks!
As your unit is a package unit it would have a data plate with the correct charge weight, the best way though not the cheapest is to weight the refrigerant and compare it to the data plate.
An easier but not as acurate way is to measure the air on and off temperatures, if you are getting a good temperature drop or rise then its likely the charge is ok.
If you have gauges and a thermometer you could measure the suction superheat, you'd need a chart to compare the reading to though.

[@wickedxe]

thanks john, food for thought. yeah i will see how it goes in summer. i may have to dust off the gauges and buy a textbook.

[@jm69charternet]

Good video John.

[@wickedxe]

interesting vid as always john, whats the easiest way of determining if something is a little low on refrigerant? the unit in question is my aircon( there is a vid of it on my account). what are typical gauge pressures for an aircon running R22?

[@heavydiesel]

Thank you Martin!

[@ummscott]

I like your thoughts here sir....
Around here Copeland pretty much owns anything 1 horse and up and I mainly see tecumseh in the fractional horse market.
I do refrigeration and I frequently see compressors rated for air conditioning but used in medium temp 35-40 degree applications that can't seem to pumpdown like they should

[@heavydiesel]

Scott Borcherding Hi Scott, Copeland pretty much only sell scrolls here now, and the bigger semi hermetic compressors. For hermetics i like the Tecumseh/L'Unite compressors, they seem pretty robust.

[@benkuxhouse787]

trying to pump down at unit is a bad way to test for bad valves. if you have a lot of refrigerant in your system sometimes if you try to pump it down the condenser and your receiver will be so full of refrigerant you will not be to store all of the refrigerant in the system in it which I have seen more than once. a good way to test for valves is disconnecting the outdoor fan or fans drive up the head pressure see if it will trip or go beyond the trip point of your high pressure control by by jumping it out. if your valves are partially filled you'll see the high pressure increase but it will not go even close to your trip point example are 22 which usually high pressure cutouts are at 400 - 450 psig you might see a clam up to 300 in just stay there. that works on any compressor even semi-hermetic. if that unit was cooling and keep in the box at temperature it was working fine. Another dead giveaway is to check that discharge line it should be very hot to the touch and sometimes with partially failed valves it will be luke warm but not hot. semi hermetic compressors are little different sometimes if its by passing too much when the unit is pumped down through the head then you need a valve plate but partially failed valves is when the compressor is not raising the temperature of the gas to a high enough level the disconnecting that outdoor fan or fans and see what happens to your head pressure is really good test because of the valves are partially failed they won't go up even close to the trip point. remember an overcharged system lot of times you can not pump all that gas into your condensing unit because you filled up with so much refrigerant there is no room for all the refrigerant in the system, especially if somebody over sizeed the liquid line. it takes a lot of excess refrigerant filled out liquid line it will still work but you have to put a lot of refrigerant in the system to make it work I have replaced liquid mind that I know where oversized because of all the refrigerant I had to put in the system.

[@heavydiesel]

+Ben Kuxhouse These systems were being pumped down to facilitate them being moved. The problem with the Copeland compressor became apparent after it failed to get below approximately 10psi. To help diagnose the problem I then shut the suction valve on the compressor and it still failed to pull into a vacuum, indicating the valves were in poor condition. (it should be able to pull 16-20in.Hg vacuum if working correctly without an excessive head pressure). If the system was overcharged it would have cycled off on the high pressure control, if there were no high pressure switch the internal pressure relief would operate to vent the excess pressure back into the suction side of the compressor, this is highly audible and would correspond with a sudden rise in suction pressure. Basically this compressor was worn out.

[@benkuxhouse787]

+heavydiesel bad valves I never seen the equipment be able to keep up with the load because its not working efficiently enough but I have seen on equipment that's overcharge the inability to pump down because it's all stored in that the condenser and that's my only concern is that it must have been working properly and I would just recover the rest and move the equipment then once you get it in place started up you can always tell your concerns to the customer but my experience with compressors and bad valves n hermetic reciprocating compressors is bad valves can't keep up with the load

[@workkevinw]

You do know to only do 2 turns in in the king valve or you block off the compressor?!?

[@heavydiesel]

This is being decommissioned so it can be moved.

[@primetime758]

did you end up re-installing these units for the new buyer?

[@heavydiesel]

Not this one, I just decommissioned it for another company who had bought it.

[@TheSatchrox]

Recent Tecumseh compressors, based on everything I have heard about them, are lacking in quality compared to other brands.

[@lakhwindersekhon4370]

Plz snd DR29K6ME compressor video

[@heavydiesel]

I have no idea what compressor that is and consequently have no video to send.

[@UltraHydrophobiccoat]

Where can buy this kind of valve at 0:10? Thanks

[@heavydiesel]

Refrigeration wholesalers should be able to get Rotalock valves, you need to know the pipe size, brazed or flared connection and the nut size where it screws onto the compressor.
You don't necessarily need the same make valve as the compressor so long as all the connection sizes are the same. You can save some money doing this as Copeland only sell the valves as a pair but Maneurop will sell them individually for example.
You will also need a new o ring for the valve to compressor joint, some valve are supplied with the and others aren't.