Section 22: HEATING AND AIR CONDITIONING
PA1562
27
superheat spring, causing the valve pin to move
in the opening direction. Conversely, as the
temperature of the
refrigerant
gas leaving the
evaporator decreases, the pressure in the
remote bulb and power assembly also
decreases and the combined evaporator and
spring pressures cause the valve pin to move in
the closing position.
FIGURE 32: EXPANSION VALVE
22045
As the operating superheat is raised, the
evaporator capacity decreases, since more of
the evaporator surface is required to produce
the superheat necessary to open the valve. It is
obvious, then, that it is most important to adjust
the operating superheat correctly and that a
minimum change in superheat to move the valve
pin to full open position, is of vital importance
because it provides savings in both initial
evaporator cost of operation. Accurate and
sensitive control of the refrigerant liquid flowing
to the evaporator is necessary to provide
maximum evaporator capacity under load
conditions. The spring is adjusted to give 12 to
16
o
F (-11.1 to -8.8
o
C) of superheat at the
evaporator outlet.
This ensures that the refrigerant leaving the
evaporator is in a completely gaseous state
when drawn into the suction side of the
compressor. Liquid would damage the
compressor valve, piston and heads if allowed
to return in the suction line.
A vapor is said to be superheated when its
temperature is higher than the saturation
temperature corresponding to its pressure. The
amount of the superheat is, of course, the
temperature increase above the saturation
temperature at the existing pressure.
As the refrigerant moves along in the
evaporator, the liquid boils off into a vapor and
the amount of liquid decreases until all the liquid
has evaporated due to the absorption of a
quantity of heat from the surrounding
atmosphere equal to the latent heat of
vaporization of the refrigerant. The gas
continues along in the evaporator and remains
at the same pressure. However, its temperature
increases due to the continued absorption of
heat from the surrounding atmosphere. The
degree to which the gas refrigerant is
superheated is related to the amount of
refrigerant being fed to the evaporator and the
load to which the evaporator is exposed.
Superheat Adjustment
The starting method of adjusting the superheat
is to unscrew completely the main evaporator
expansion valve adjusting screw, then screw in
13 turns clockwise for 134A (Fig. 33).
Afterwards, the following procedure should be
followed:
1. Operate coach for at least one-half hour at
fast idle with temperature control set at 82
o
F
(27,7
o
C), Then set temperature to minimum
to keep the compressor on 6 cylinders.
2. Install pressure gauge at the evaporator
suction header. You may install the
pressure gauge at compressor suction, but
then add 3 psi to reading.
Summary of Contents for X3-45 Multiplex
Page 1: ...COACH MANUFACTURER MAINTENANCE MANUAL X3 COACHES PA1562 4th edition...
Page 13: ...Section 00 GENERAL INFORMATION 11 PA1562 FIGURE 16 METRIC US STANDARD CONVERSION TABLE 00005...
Page 14: ...Section 00 General Information PA1562 12 FIGURE 17 CONVERSION CHART 00006...
Page 30: ......
Page 110: ......
Page 236: ......
Page 253: ...FAULT CODE MANUAL Created on 00 04 25 15 30 1 FAULT CODE MANUAL B7L B7TL B12...
Page 278: ......
Page 317: ......
Page 318: ......
Page 319: ......
Page 320: ......
Page 321: ......
Page 322: ......
Page 323: ......
Page 324: ......
Page 325: ......
Page 326: ......
Page 327: ......
Page 328: ......
Page 329: ...DQD 6SLFHU ULYHVKDIW 6HUYLFH 0DQXDO 660 XO 6HULHV 8QLYHUVDO RLQWV DQG ULYHVKDIWV...
Page 372: ......
Page 379: ......
Page 439: ...Forward and Rear Axle Carrier Diagnostic Flowcharts TP 99125 Issued 12 99 TECHNICAL BULLETIN...
Page 484: ......
Page 494: ......
Page 500: ...Notes Copyright 2002 Maintenance Manual MM 0204 Page 4 ArvinMeritor Inc Issued 08 02...
Page 504: ...Notes Copyright 2002 Maintenance Manual MM 0204 Page 8 ArvinMeritor Inc Issued 08 02...
Page 526: ...16 BW2158 Honeywell Commercial Vehicle Systems Company 4 2001 Printed in USA...
Page 530: ......
Page 538: ......
Page 546: ......
Page 553: ......
Page 566: ......
Page 702: ......
Page 760: ......
Page 778: ......
Page 779: ......
Page 780: ......
Page 781: ......
Page 782: ......
Page 783: ......
Page 784: ......
Page 785: ......
Page 786: ......
Page 787: ......
Page 788: ......
Page 789: ......
Page 790: ......
Page 791: ......
Page 792: ......
Page 793: ......
Page 794: ......
Page 795: ......
Page 796: ......
Page 797: ......
Page 798: ......
Page 799: ......
Page 800: ......
Page 801: ......
Page 802: ......
Page 803: ......
Page 804: ......
Page 805: ......
Page 806: ......
Page 807: ......
Page 808: ......
Page 809: ......
Page 810: ......
Page 811: ......
Page 812: ......
Page 813: ......
Page 814: ......
Page 815: ......
Page 816: ......
Page 817: ......
Page 818: ......
Page 819: ......
Page 820: ......
Page 821: ......
Page 822: ......
Page 823: ......
Page 824: ......
Page 825: ......
Page 826: ......
Page 827: ......
Page 828: ......
Page 829: ......
Page 830: ......
Page 831: ......
Page 832: ......
Page 833: ......
Page 834: ......
Page 835: ......
Page 836: ......
Page 837: ......
Page 838: ......
Page 839: ......
Page 840: ......
Page 841: ......
Page 842: ......
Page 843: ......
Page 844: ......
Page 845: ......
Page 846: ......
Page 847: ......
Page 848: ......
Page 849: ......
Page 850: ......
Page 851: ......
Page 852: ......
Page 853: ......
Page 854: ......
Page 855: ......
Page 856: ......
Page 857: ......
Page 858: ......
Page 859: ......
Page 860: ......
Page 861: ......
Page 862: ......
Page 863: ......
Page 864: ......
Page 865: ......
Page 866: ......
Page 867: ......
Page 868: ......
Page 869: ......
Page 870: ......
Page 871: ......
Page 872: ......
Page 873: ......
Page 874: ......
Page 875: ......
Page 876: ......
Page 877: ......
Page 878: ......
Page 880: ......
Page 941: ...Initial Installation Section 2 Initial Installation Installation 14 Maintenance Tips 15...
Page 965: ...Glossary Section 5 Glossary Glossary 39...
Page 967: ......
Page 1012: ......
Page 1115: ......
Page 1116: ......
Page 1118: ......
Page 1119: ......
Page 1123: ......
Page 1124: ......
Page 1125: ......
Page 1126: ......
Page 1127: ......
Page 1128: ......
Page 1130: ......
Page 1133: ......
Page 1134: ......
Page 1136: ......
Page 1138: ......
Page 1139: ......
Page 1140: ......
Page 1141: ......
Page 1142: ......
Page 1196: ......
Page 1197: ...Compressor 62 11052 Rev A WORKSHOP MANUAL for MODEL 05G TWIN PORT COMPRESSOR R...
Page 1198: ...WORKSHOP MANUAL COMPRESSOR MODEL 05G TWIN PORT...
Page 1221: ...Compressor 62 11053 Rev B SERVICE PARTS LIST for MODEL 05G TWIN PORT COMPRESSOR 1 2 3 4 5 6 R...
Page 1249: ......
Page 1250: ......
Page 1251: ...1...
Page 1252: ...2...
Page 1253: ...3...
Page 1254: ...4...
Page 1255: ...5...
Page 1256: ...6...
Page 1257: ...7...
Page 1258: ...8...
Page 1259: ...9...
Page 1260: ......
Page 1265: ...Section 23 ACCESSORIES PA1562 5 FIGURE 2 AUDIO VIDEO CONNECTIONS...
Page 1278: ...Section 23 ACCESSORIES PA1562 18 FIGURE 26 FUNCTIONING OF LAVATORY 23051...
Page 1294: ......
Page 1301: ......
Page 1350: ......
Page 1351: ......
Page 1352: ......
Page 1353: ......
Page 1354: ......
Page 1355: ......
Page 1356: ......
Page 1357: ......
Page 1358: ......
Page 1359: ......
Page 1360: ......
Page 1361: ......
Page 1362: ......
Page 1363: ......
Page 1364: ......
Page 1365: ......
Page 1366: ......
Page 1367: ......
Page 1368: ......
Page 1369: ......
Page 1370: ......
Page 1371: ......
Page 1372: ......
Page 1373: ......
Page 1374: ......
Page 1375: ......
Page 1376: ......
Page 1377: ......
Page 1378: ......
Page 1379: ...LPCM OUTPUT...
Page 1380: ......
Page 1381: ......
Page 1382: ......
Page 1383: ......
Page 1384: ......
Page 1385: ......
Page 1386: ......
Page 1406: ......
Page 1410: ......
Page 1418: ......