McQuay PEH087 - "Vane Closed" Switch

[moondoggie]

McQuay PEH087 chiller - vane closed switch problem

After running vanes closed in manual, there is not enough oil pressure to close the vane closed switch. Switch has been adjusted to mininium setpoint. System oil pressure is 50 PSI net.

Can anyone guide me in the right direction?

Thanks

[freonrick]

if you have only 50psi net oil then it is too low. it should be double that.

[refrtech]

That is not a good thing !! 50 psi is 1/2 of what you need. It sounds like you are losing oil which is never a good thing ! Call McQuay Service in your area. :)

[moondoggie]

Oil pressure is 50psig over chiller pressure so it is Appr. 110psig.This would be running the oil pump in service test mode.

[chilbrig]

There is a quarter inch copper line that is hooked up to one of the service valves on top of the oil sump. Make sure the service valve is cracked open so that the quarter inch line is able to drain to the sump.

[freonrick]

your oil pressure should be app. 100 lbs over oil sump pressure.

[chiller mekanik]

What chilbrig said.


Make sure someone hasn't serviced or repaired the machine recently, that valve ends up in the wrong position often enough.

[captinsano]

after you make sure the low side of the vc service valve is cracked of the backseat like chillbrig said check to make sure you have a solid 24v to the sa coil to unload.if neither of those put you in the right direction hteir are a few other tests you can perform to find your problem you just need a few 1/4 swivel ts,gauge set,and nitro bottle.let me know if you need this info.also forgot another easy one turn the sa needle in all the way to its seat count # of turns and back out to original spot sometimes trash will get caught in the valve and this will sometimes get it going.whatever you do dont jumpout vc.
setting for vc is 40 psid,check cal.

hope this helps.

[moondoggie]

Problem solved......It ended up being the bellows on the vane cosed switch leaking from the high side to the low side. This is why I could not get the differential requied at the switch.

Thanks for all you help!