| Table 1: | Quick Look-Up Troubleshooting Table |
| Table 2: | R-134a Temperature/Pressure Parameters |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 |
Were diagnostic codes found? | -- | ||||||||||
2 |
Does the blower motor speed increase at each speed level when blower speed selector switch is turned to HI and then decreases as the switch is moved towards LO? | -- | ||||||||||
3 | Inspect for a loose, damaged or missing compressor drive belt. Is the action complete? | -- | -- | |||||||||
4 | Inspect the engine coolant fan operation. Is the action complete? | -- | -- | |||||||||
5 |
Is the action complete? | -- | -- | |||||||||
6 |
Does the compressor clutch engage? | -- | ||||||||||
7 |
Is the compressor noise excessive? | -- | ||||||||||
8 | Feel the liquid line between the condenser and the receiver/dryer. The line should feel warm to the touch. Does the line feel cold? | -- | ||||||||||
9 |
Are both Lo and Hi pressures the same as or higher than specified value? | 345 kPa (50 psi) | ||||||||||
10 | Monitor and compare Lo and Hi pressure readings. Are both Lo and Hi pressures the same as or higher than specified value? | 69345 kPa (1050 psi) | ||||||||||
11 | Inspect the system for refrigerant leaks. Was the refrigerant leak found? | -- | ||||||||||
12 | Feel the evaporator inlet pipe (small pipe) and evaporator outlet pipe at bulkhead. The evaporator inlet pipe should feel warm to the touch. Does the inlet evaporator pipe feel colder than the evaporator outlet pipe? | -- | ||||||||||
13 | Inspect the system for refrigerant leaks. Was the refrigerant leak found? | -- | ||||||||||
14 | Monitor compressor clutch cycle rate. Was the compressor clutch cycle rate more than 8 cycles per minute? | -- | ||||||||||
15 |
Does inlet evaporator pipe feel colder than the evaporator outlet pipe? | -- | ||||||||||
16 |
Does the heater inlet hose feel hot? | -- | ||||||||||
17 | Inspect HI pressure. Does the compressor engage within specified values? | 196-3140 kPa (28-455 psi) | ||||||||||
18 |
Did the compressor stay engaged outside specified values? | 196-3140 kPa (28-455 psi) | ||||||||||
19 | Refer to Blower Motor Inoperative at Any Speed . Is the action complete? | -- | -- | |||||||||
20 | Refer to Blower Motor Inoperative at Any Speed . Is the action complete? | -- | -- | |||||||||
21 | Refer to Noise Diagnosis and determine the cause of excessive compressor noise. Is the action complete? | -- | -- | |||||||||
22 | Repair restriction in the HI side of the refrigerant system. Visually check for a line/pipe frosty spot to locate restriction. Is the action complete? | -- | -- | |||||||||
23 | Correct and/or repair code setting criteria. Is the action complete? | -- | -- | |||||||||
24 | Repair the refrigerant leak. Is the action complete? | -- | -- | |||||||||
25 |
Refer to Refrigerant Recovery and Recharging . Is the action complete? | -- | -- | |||||||||
26 | Evacuate and recharge the system. Refer to Refrigerant Recovery and Recharging . Is the action complete? | -- | -- | |||||||||
27 | Inspect the Heater Water Valve for a leaking or constantly-open. Is the action complete? | -- | -- | |||||||||
28 | Replace the A/C dual pressure switch. Is the action complete? | -- | -- | |||||||||
29 | Perform the A/C performance test. Is the action complete? | -- | System OK | -- |
Set controls to: NORMAL mode, HI blower, Lowest °C (°F) setting, Window open | |||
|---|---|---|---|
Pressures as compared to a normal operating system | |||
A/C NOT COLD | HI-SIDE PSI | LOW-SIDE PSI | RELATED SYMPTOMS |
Undercharge | Low | Low | Compressor Grumbling Heard Inside of Vehicle |
TXV Failure or Stuck Closed | Low | Low | Low-side Gauge Fluctuation |
Low Side Restriction | Low | Normal to Low | Hose Kinked or Restricted |
Engine Cooling Fan(s) Inoperative | High | High | Confirm Operation of Fan and Direction of Rotation |
Overcharged | High | High | Compressor Cutting Out Due to High Pressure |
Air in System | High | High | Compressor Cutting Out; Evaporator Freeze Up Possible |
Restricted Airflow Across Condenser | High | High | Visually Inspect |
TXV Stuck Open | High | High | Rapid Pressure Equalization on Shutdown; Slugging Noise Heard from Evaporator on Startup |
Clutch/Relay/Electrical Failure | Low | High | Compressor Clutch Does Not Engage/High and Low-Side Pressures are Equal |
Internal Compressor Failure | Low | High | No Change ON vs. OFF; High and Low-Side Pressures are equal |
High-Side Restriction | Normal to High | Normal to Low | Feel High Side Hose/Piping for Abrupt Drop in Temperature |
°C | °F | kPa | PSI | °C | °F | kPa | PSI | ||
|---|---|---|---|---|---|---|---|---|---|
-9 | 16 | 106 | 15 | 38 | 100 | 857 | 124 | ||
-8 | 18 | 115 | 17 | 39 | 102 | 887 | 129 | ||
-7 | 20 | 124 | 18 | 40 | 104 | 917 | 133 | ||
-6 | 22 | EVAP. RANGE | 134 | 19 | 41 | 106 | 948 | 137 | |
-4 | 24 | 144 | 21 | 42 | 108 | 980 | 142 | ||
-3 | 26 | 155 | 22 | 43 | 110 | COND. RANGE | 1012 | 147 | |
-2 | 28 | 166 | 24 | 44 | 112 | 1045 | 152 | ||
-1 | 30 | 177 | 26 | 46 | 114 | 1079 | 157 | ||
0 | 32 | 188 | 27 | 47 | 116 | 1114 | 162 | ||
1 | 34 | 200 | 29 | 48 | 118 | 1149 | 167 | ||
2 | 36 | 212 | 31 | 49 | 120 | 1185 | 172 | ||
3 | 38 | 225 | 33 | 50 | 122 | 1222 | 177 | ||
4 | 40 | 238 | 35 | 51 | 124 | 1260 | 183 | ||
7 | 45 | 272 | 40 | 52 | 126 | 1298 | 188 | ||
10 | 50 | 310 | 45 | 53 | 128 | 1337 | 194 | ||
13 | 55 | 350 | 51 | 54 | 130 | 1377 | 200 | ||
16 | 60 | 392 | 57 | 57 | 135 | 1481 | 215 | ||
18 | 65 | 438 | 64 | 60 | 140 | 1590 | 231 | ||
21 | 70 | 487 | 71 | 63 | 145 | 1704 | 247 | ||
24 | 75 | 540 | 78 | 66 | 150 | 1823 | 264 | ||
27 | 80 | 609 | 88 | 68 | 155 | 1948 | 283 | ||
30 | 85 | 655 | 95 | 71 | 160 | 2079 | 301 | ||
32 | 90 | 718 | 104 | 74 | 165 | 2215 | 321 | ||
35 | 95 | 786 | 114 | 77 | 170 | 2358 | 342 |
