5 ton trane package unit HP single stage 460v 3 phase.

[HVAC_HUSKER]

evaperator fan turns on amp draw is fine, condenser fan and compressor turn on after delay but only for 5-10 seconds and loses 24 volts to cond. fan relay and to compressor contactor. i have 480 volts at contactor, 24 volts going into control board, high and low pressure switch stay closed, amp draw appears to be fine but not sure dont have much time to check. cond. fan motor and compressor dont feel hot to the touch. i am asuming control board is bad... any help appreciated. thanks guys..

[MicahWes]

Does the unit have an economizer?

[HVAC_HUSKER]

Yes but temps were too high and economizer was not open. If econimizer was in use compressor or cond. fan wouldnt even try to start plus economizer would be open.. led indicated for economizer to remain close and run normal single stage cooling.

[OuTcAsT]

Is this a Voayger unit ? Fault codes would help, but sounds like the High pressure control is tripping. Do you have guages on when it trys to start?

[Kon99lbi]

With the information you gave, sounds like something on the control board is taking out 24V to your contactor shortly after the unit fires up. You mentioned that the Hi/Lo press switches check out fine. Is there anything in your cooling circuit (Y) that could be the culprit? Current sensing relay? compressor lock out relay? Does the control board reset? or is it no longer functioning? If your not finding enough time to check amperage after the unit fires up, "when in doubt, jump it out!" and see whats your amp draw is.