Important: Perform this test under garage conditions with the air temperature at 21-32°C (70-90°F), and no sun load. Follow this test carefully for accurate results.
Important: Perform this test exactly as described to obtain accurate results.
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Record the customer's complaint. Can you verify the customer's complaint? | -- | Go to Step 2 | System OK | ||||||||
2 |
Is the discharge air temperature normal? | At least 7°C (12°F) below ambient air temperature | System OK | Go to Step 3 | ||||||||
3 |
Do both pressures measure within the specified range? | 69-345 kPa (10-50 psi) | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Do both pressures measure greater than the specified value? | 345 kPa (50 psi) | Go to Step 7 | Go to Step 1 | ||||||||
5 | Observe the 2 pressure gages. Do both pressures measure less than the specified value? | 69 kPa (10 psi) | Go to Step 6 | Go to Step 7 | ||||||||
6 |
Do both pressures measure above the specified value? | 345 kPa (50 psi) | Go to Step 7 | Go to Step 1 | ||||||||
7 |
Does the A/C compressor clutch engage? | -- | Go to Step 8 | Go to Step 10 | ||||||||
8 |
Do you hear a loud knocking noise? | -- | Go to Step 9 | Go to Step 13 | ||||||||
9 |
Is the compressor running normally? | -- | Go to Step 13 | Go to Step 1 | ||||||||
10 |
Does the A/C clutch engage? | -- | Go to Step 11 | Go to Step 12 | ||||||||
11 | Repair the electrical circuit to the A/C compressor clutch coil. Does the A/C clutch engage? | -- | Go to Step 8 | Go to Step 1 | ||||||||
12 | Replace the A/C compressor clutch coil. Does the A/C clutch engage? | -- | Go to Step 8 | Go to Step 1 | ||||||||
13 |
Is there a noticeable difference in the temperature of the evaporator inlet and outlet pipes? | -- | Go to Step 15 | Go to Step 14 | ||||||||
14 |
Is the discharge temperature normal? | At least 7°C (12°F) below ambient air temperature | Go to Step 15 | Go to Step 13 | ||||||||
15 |
Do the low and high side pressures intersect in the white area of the chart? | -- | System OK | Go to Step 16 | ||||||||
16 | Inspect the low and high side pressures. Do the low and high side pressures intersect in the gray area of the chart? | -- | Go to Step 17 | Go to Step 20 | ||||||||
17 | Feel the liquid pipe between the condenser and the expansion valve. Is the pipe cold? | -- | Go to Step 18 | Go to Step 19 | ||||||||
18 |
Is the pipe temperature at or below the specified value? | At least 7°C (12°F) below ambient air temperature | Go to Step 13 | Go to Step 1 | ||||||||
19 |
Is the system free from leaks? | -- | Go to Step 13 | Go to Step 1 | ||||||||
20 | Observe the readings on the pressure gages. Are the A/C compressor low and high side pressures within the specified value of each other? | 207 kPa (30 psi) | Go to Step 21 | Go to Step 26 | ||||||||
21 |
Are the A/C compressor low and high side pressures within the specified value of each other? | 207 kPa (30 psi) | Go to Step 22 | Go to Step 13 | ||||||||
22 | Observe the pressure rise on both gages and the temperatures of both the compressor suction pipe and the discharge pipe. Is the pressure rise on both gages slow and the suction pipe warm with the discharge pipe very hot? | -- | Go to Step 25 | Go to Step 23 | ||||||||
23 |
Can you turn the clutch driver freely by hand? | -- | Go to Step 25 | Go to Step 24 | ||||||||
24 |
Does the low side pressure rise rapidly? | -- | Go to Step 32 | Go to Step 25 | ||||||||
25 |
Is the compressor functioning normally? | -- | Go to Step 13 | Go to Step 1 | ||||||||
26 | Measure the low side pressure. Does the low side pressure measure within the specified value? | 172-241 kPa (27-38 psi) | Go to Step 27 | Go to Step 32 | ||||||||
27 | Feel the high side pipe leading up to the expansion valve connecting block. Is the pipe cold before the connecting block? | -- | Go to Step 28 | Go to Step 29 | ||||||||
28 |
Is the pipe performing normally? | -- | Go to Step 13 | -- | ||||||||
29 | Add the specified amount of refrigerant to the A/C system. Does the cooling performance improve? | 0.40 kg (14 oz) | Go to Step 30 | Go to Step 31 | ||||||||
30 |
Is the system free from leaks? | -- | Go to Step 13 | Go to Step 1 | ||||||||
31 |
Is the system free from leaks? | -- | Go to Step 13 | Go to Step 1 | ||||||||
32 |
Does the low side pressure measure within the specified range? | 172-241 kPa (25-35 psi) | Go to Step 13 | Go to Step 33 | ||||||||
33 |
Is the system free from leaks? | -- | Go to Step 13 | Go to Step 1 |