York DM090 installation manual Unitary, 5005, Norman, Products, York, Group, Drive, 73069

terminal. If 24 volts is not present, check for loose wiring from the Y1 “OUT” terminal to the Mate-N-Lock plug, a poor connection between the UCB and economizer Mate-N-Lock plugs, loose wiring from the Mate-N-Lock plug to the economizer, back to the Mate-N-Lock plug, and from the Mate-N-Lock plug to the Y1 “ECON” terminal. The economizer control may have faulted and is not returning the 24 volts to the Y1 “ECON” terminal even though the economizer is not providing free cooling. To test the economizer control, disconnect the Mate-N-Locks and jumper between the WHITE and YELLOW wires of the UCB’s Mate-N-Lock plug.

13.The UCB can be programmed to lock out compressor operation during free cooling and in low ambient condi- tions. These options are not enabled by default. They can be checked by local York distributors.

14.If none of the above corrected the error, test the integrity of the UCB. Disconnect the C1 terminal wire and jumper it to the Y1 terminal. DO NOT jump the Y1 to C1 termi- nals. If the compressor engages, the UCB has faulted.

15.If none of the above correct the error, replace the UCB.

Subject to change without notice. Printed in U.S.A.	035-17311-003-A-0704
Copyright © 2004 by Unitary Products Group. All rights reserved.	Supersedes: 035-17311-002-A-0803

Unitary	5005	Norman
Products	York	OK
Group	Drive	73069