York units and high head

[bulletproof]

I have 3 seperate York roof top package units all three have went down this week on the control board from high head pressure.I have cleaned the condenser coils but still running a 70/290 pressures.It has been 95 to 100 degrees all week.I dont think i have any kind of a restriction.But have noticed that York units tend to undersize there filter dryers.Ive also noticed on some units mainly the units with scroll compressors. When the unit first starts up the head pressure shoots up almost to 340 then comes back to normal.They dont do this every time but Ive seen it lock out on high head before from this.Any ideas on what i could try to lower the head.Iam pretty sure airflow isnt the problem.

[berg2666]

70/290 on a 100 degree day is good,maybe low charge.


You said you wanted to lower the head pressure.

How much lower do you want?

Did you check the subcooling and superheat. If your superheat is high I would guess an undercharge condition.

[y7turbo]

did you split the coil when you cleaned them? if they have a split coil just cleaning them from the outside wont do anything. but a 290 head on a 100 deg day is right around where you want to be.

when the unit first starts do the condenser fans come on or do they wait for a pressure control? maybe that has failed.

as for the driers you talked about, check the td on both sides of them, if its more then a few deg, they are causing a restriction..