ALARM TROUBLE SHOOTING
Refrigerant System Alarm Codes (01, 02, 03, 04, 09, 10, 11, 12)
The first 12 alarms involve controls intended to protect the compressors. Each compressor system is equipped with external circuitry monitoring hardware intended to protect the compressor in case the operating characteristics of the refrigerant system fall outside the safe operating envelope for the compressor. The type of protection varies depending on the type of compressor used.
YPAL 050 Compressors 1A, 1B, 2A, and 2B YPAL 051 Compressors 1A, 1B, 2A, and 2B YPAL 060 Compressors 1A and 2A YPAL 061 Compressor 1A
The Compressor Safety Circuit consists of a high- pressure cutout switch. Each of the compressors is also protected by internal line break switch imbedded in the windings of the compressor that protects the compressor from excessive current or temperatures. The Unit Controller will not be able to identify the internal line break switch is open and no fault will be generated or reported by the Unit Controller.
If the internal line break is open it will appear as a compressor failure. To trouble shoot verify the compressor contactor for the compressor that is not running, is closed and line voltage is present on the load and line side of all three legs. If so remove power from the unit and remove the cover from the compressor control box. Check for an open winding. If all three winding are open carefully check the compressor shell. If the shell is hot no determination can be made until the shell has cooled. If the shell is cool and a winding is open the compressor is defective. If the windings close as the compressor cools the internal line break switch was open. Some possible causes for an open switch are, high discharge super heat (low charge), start of a bearing failure (partial locked rotor), or high voltage.
The above units also have a low- pressure cutout that will be discussed later.
FORM
Since tandem compressors are used there is a single high pressure switch for system 1 and one for system 2. If the high pressure switch opens both of the compressors for that system will be turned off. If the high pressure switch for system 1, (compressors 1A, 1B), opens it will generate both a 01 and 02 alarm code. Likewise if the high pressure switch opens for system 2, (compressors 2A, 2B), opens it will generate both a 03 and 04 alarm code.
The high pressure switch opens at 625 PSIG and closes at 500 PSIG. In order to generate a high pressure lockout the high pressure switch must open three times within a 2 hour window.
24 VAC power is supplied to the system 1 high pressure switch circuit from wire 399 at terminal HPS1 of the P15 connector. The binary input back to the Unit Controller from the high pressure switch is wire 400 at terminal HPS1 of the P15 connector. The above input is then jumpered to terminal HSP2 of the P15 connector.
24 VAC power is supplied to the system 2 high pressure switch circuit from wire 431 at terminal HPS3 of the P16 connector. The binary input back to the Unit Controller from the high pressure switch is wire 432 at terminal HPS3 of the P16 connector. The above input is then jumpered to terminal HPS4 of the P16 connector.
Because there is no external compressor protection module on these models jumpers are placed between terminals C10 and C10 of the P12 connector for compressor 1A, C20 and C20 of the P12 connector for compressor 1B, C30 and C30 of the P12 connector for compressor 2A, and C40 and C40 of the P12 connector for compressor 2B.
YPAL 060 Compressors 1B and 2B
YPAL 061 Compressors 1B, 2A and 2B
The high pressure switches are connected as described above; however, the compressors identified above employ a compressor protection module. 24 VAC power is supplied to the compressor protection module for compressor 1B from wire 441 at terminal C20 of the P12 connector. The binary input back to the Unit Controller from the compressor protection module is wire 440 at terminal C20 of the P12 connector.
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JOHNSON CONTROLS | 163 |
