McQuay 4way solenoid!!!!!

[flemsteele]

Hello All,


Gotta a little problem with a McQuay PE079 machine ? The problem pertains to the vanes and the 4-way solenoid that operates them.


I got a couple of questions if anybody can help that would be great.

1} Is there a way to test these vanes , open and close with nitrogen at the oil lines on the compressor? To see if the piston itself is stuck?

2}I had a problem last week where the vanes would not open, checked solenoid , I had power to it, tried adjusting vane opening speed on the bleed valves still NOTHING. Called McQuay tech support, they said the 4way was no good , so I ordered another one, by the way the new ones require a little oil line change , and the valve only has 4 ports not 5. So after I install new valve I try and start the machine , vane closure switch is holding it out so being the wise man that i am I jumped it out to start the chiller, and would'nt you know it starts FULLY loaded, I WOULD NOT RECCOMEND THIS!!! So now shes running fully loaded the control is telling it to unload .... nothing she stays loaded. i check oil preesures @ the ports on the compressor , I got 145-155psi on the right hand oil line which I'm assuming is the unload line from the solenoid. The left hand one has 45psi . When I say left and right I'm talking about the three ports on the compressor then the third port is just below the otheer two. I believe is the drain line to the sump. Tried adjusting vane closure speed according to the manual .....NOTHING . I am leaning toward a stuck piston. I am about at my wits end . Am I missing something ?


Bill

[absrbrtek]

Sounds like youve covered all your bases. Probably need to pull the assembly out and re o-ring it.

[btexpress]

The 1/4" connection towards the suction elbow is the unload port, the connection towards the compressor is the load port. The connection below the two is the high side of the vane close switch. The drain should be two other ports going back to the gearcase. If the o-rings are good in the front end, the front end can be bled down and manually pumped open and closed. You need to close the 1/4" service valve at the filter cavity and back seat the service valve on the oil pump return line at the sump to close off the 1/4" port. Hope this helps.

[lew2]

btexpress has it right!!

Typically pressure taps on the lines for load, unload, and what is referred to as VC high will reveal what is going on. IMO.

Vane close problems typically fall into about 4 items.

1. Simple trash in the SA/SB valve that can be flushed by opening the needle valves and loading and unloading the compressor.

2. Problems with the mechanical part of the VC switch. For example the diaphram leaking.

3. The electrical portion of the switch not working correctly.

4. Actual problems within the inlet guide vane assembly.
If this is the problem check into the quad ring kits to repair the vane assembly. This kit is not used on all compressors, however, this is the real deal for some frame sizes. This problem may be more than a simple O ring type of failure (don't know until you know).

Something to keep in mind today is that on units equipped with VFD's a vane open switch is used as well as a vane close switch.

The new switches used are different from the older ones. The older vane assemblies had 1/4 in flare fittings. The newer ones typically have steel lines and hydraulic type fittings.

Hope this helps.

[freonrick]

some machines had the oil drain line from the 4 way valve going to the service valve on the oil pot. make sure it is not back seated or it cant bled off. after you fix the problem set the bleed on the valve so it takes app. 3 minutes to fully load and 1 minute to unload

[freonrick]

as far as testing with nitrogen, that is how i test it during reassembly. but if you do it with freon in the system and your o-rings leak you will contaminate the system.

[kcl]

btexpress is right. From suction connection left port is closed, right port is open, center port is vane closed switch connection. Sounds like the solenoids might be wired wrong being that your getting 145 psi at the open port. Try reversing the solenoid valve wiring. Remember front door closed, back door open.

[flemsteele]

Tried swapping the solenoid leads, no luck . This is an R12 machine circa 1984, these CHEAP SOB's that own this machine have done nothing to it for quite awhile yet expect it to run like a newer machine . So I'm trying to convince them to overhaul this piece of garbage and convert to 134a. If I gotta open it up I mine as well do the whole kit and kaboodle!!

[absrbrtek]

Priced up a conversion on one of these junkers last year. Needed retubing and a gear change to get it to run at 100% of the original capacity as the R12. Was quite a hefty quote for the conversion.

Originally posted by flemsteele
Tried swapping the solenoid leads, no luck . This is an R12 machine circa 1984, these CHEAP SOB's that own this machine have done nothing to it for quite awhile yet expect it to run like a newer machine . So I'm trying to convince them to overhaul this piece of garbage and convert to 134a. If I gotta open it up I mine as well do the whole kit and kaboodle!!

[freonrick]

i converted one a few years ago and had to replace condenser tubes and change gears. a gained an extra 2 degrees out of it. it is not worth the money. also they would not sell us the kit to the it without going to their school first even though my boss use to be their factory tech.

[flemsteele]

Here is the update.

The vanes get stuck either fully open or closed ... right now they are stuck fully open . I'll be removing gas from this PIG tomorrow! Also gotta order parts ... that should be interesting? Gonna replace the "O" rings and check and see how bad this piece of garbage looks on the inside.

Bill

[lew2]

freonrick

Do you work for John???

If so tell him Lew said HI.

Thanks

[flemsteele]

Well I just got this piece of garbage apart. The piston is worn. Its worn real bad at the spots where the diffuser stops hit it , 5 weeks to get a new one!! I thought Trane was bad , McQuay S*cks!!!!