high head lock out

[Abrnth3]

Have a Leibert unit that is continuiously locking out on high head pressure. Haved ohmed out high press switch and guaged pressures, all ok while unit in opperation, then usually with in 3-4 days unit locks out on high head press. Condenser is on the roof and has been 15-30 degrees out side temp. Cooling a control room for University tv station. Any Ideas?

[GT Jets]

Yep, quite a few actually..

Likely the issue is related to refrigerant charge or the condenser fan controls.

[Abrnth3]

Replaced condenser fan about a month ago, and pressures look good. Was going to remove TEV from Evap to see if it may be causing me problems. The unit runs 3-4 days no problem, then I get called due to it being locked out on high head.

[GT Jets]

Replaced condenser fan about a month ago, and pressures look good. Was going to remove TEV from Evap to see if it may be causing me problems. The unit runs 3-4 days no problem, then I get called due to it being locked out on high head.

How many condenser fans are there and are any of them on a P66?

You have to remember that typically the hps is on the discharge of the compressor. Not the liquid line.

I would check the refrigerant charge and the condenser again.

Good hunting.

GT

[Abrnth3]

1 condenser fan. P66, is this a cold wheather kit ? HPS is on the discharge of compressor. Will check charge again but, pressures were good when I reset Unit and thought they would of been the highest when Unit was trying to cool the room down at start up.

[MAC AIR]

Does the cfm have a capacitor ? Did you replace it when you replaced the motor? And what about the Condenser coil (Clean/dirty)? I know these are basic questions.....

[DeltaT]

Pull the charge and recharge according to factory specs.

[RussS]

the P66 is an Electronic Fan Speed Control and is only to be used with single phase motors and intended for use with solid state motor controls.

Is that the motor type you installed?

[RussS]

the P66 is an Electronic Fan Speed Control and is only to be used with single phase motors and intended for use with solid state motor controls.

Is that the motor type you installed?

Johnson Control's .pdf is here http://cgproducts.johnsoncontrols.co...2476641482.pdf

Sounds like this is a likely culprit.

Russ

[Tommy knocker]

Are all fans coming on? Amp them out may have one laying down after some run time. Check the bearings as well, if you have one getting tight it will heat the motor up. Also check all fan controls. Verify they make and break where they should. I would eliminate all things cond air flow before any thing else.

[GT Jets]

Of you only have one fan motor then this is probably a fairly small unit. Model numbers are always helpful in these cases.

You have to keep on mind that a low charge condition can trip the discharge pressure switch also.

Keep us posted. The resolutions are more helpful to other people who read these.

[Abrnth3]

Thanks to all for the imput, I will look into this ferther and let you know what I find.

[Jettinvr6sc]

Does that new motor have sleeve bearings or ball bearings?

Sent from my SGH-I777