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HVAC Systems: Overview Honda S2000 AP1

Manual HVAC System 34 illustrations ~2523 words

Scheme 2

Scheme 2: Component Location Index
Scheme 2: Component Location Index

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Scheme 3

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Scheme 4

System Description

The air conditioning system removes heat from the passenger compartment by transferring heat from the ambient air to the evaporator. The evaporator cools the air with the refrigerant that is circulating through the evaporator. The refrigerant expands in the evaporator, and the evaporator becomes very cold and absorbs the heat from the ambient air. The blower fan pushes air across the evaporator where the heat is absorbed, and then it blows the cool air into the passenger compartment.

Scheme 5

Scheme 5: System Description
Scheme 5: System Description

This vehicle uses HFC-134a (R-134a) refrigerant which does not contain chlorofluorocarbons. Pay attention to the following service items

  1. Do not mix refrigerants CFC-12 (R-12) and HFC-134a (R-134a). They are not compatible.
  2. Use only the recommended polyalkyleneglycol (PAG) refrigerant oil (SP-10) designed for the R-134a A/C compressor. Intermixing the recommended (PAG) refrigerant oil with any other refrigerant oil will result in A/C compressor failure.
  3. All A/C system parts (A/C compressor, discharge line, suction line, evaporator, A/C condenser, receiver/dryer, expansion valve, O-rings for joints) are designed for refrigerant R-134a. Do not exchange with R-12 parts.
  4. Use a halogen gas leak detector designed for refrigerant R-134a.
  5. R-12 and R-134a refrigerant servicing equipment are not interchangeable. Use only a recovery/recycling/charging station that is U.L.-listed and is certified to meet the requirements of SAE J2210 to service R-134a air conditioning systems.
  6. Always recover refrigerant R-134a with an approved recovery/recycling/charging station before disconnecting any A/C fitting.

Scheme 6

Scheme 6: HVAC Control Unit Inputs and Outputs
Scheme 6: HVAC Control Unit Inputs and Outputs
CavityWire colorTerminal nameDescriptionSignal
1PNKM-COOLDrives air mix control motor to COOLWith ignition switch ON (II) and air mix control motor moving to COOL: battery voltage
2PNK/BLUM-HOTDrives air mix control motor to HOTWith ignition switch ON (II) and air mix control motor moving to HOT: battery voltage
3YEL/BLUM-DEFDrives mode control motor to DEFWith ignition switch ON (II) and mode control motor moving to DEF: battery voltage
4YEL/REDM-VENTDrives mode control motor to VENTWith ignition switch ON (II) and mode control motor moving to VENT: battery voltage
5GRYS5VSensor 5 V outputWith ignition switch ON (II): about 5 V
6PNK/BLKAMD-PDetects air mix control motor positionWith ignition switch ON (II) and air mix door at HOT: about 4.5 V With ignition switch ON (II) and air mix door at COOL: about 1.5V
7BRNTevaEvaporator temperature sensor inputWith ignition switch ON (II): between 1.0 V and 4.0 V depending on evaporator temperature. About 2.5 V at 72°F (22 °C).
8YEL/GRNMODE 2Mode control motor signal 2With ignition switch ON (II): about 5 V or about 0 V, depending upon mode
9BRN/WHTMODE 1Mode control motor signal 1With ignition switch ON (II) about 5 V or about 0 V, depending upon mode
10LT GRNS-COMSensor groundLess than 0.5 V at all times
11BLU/REDBLW-VPower transistor feedbackWith ignition switch ON (II) and blower OFF: between 5 V and 12 V. Voltaqe decreases as blower speed increases
12BLU/WHTACSA/C compressor ON requestWith ignition switch ON (II), A/C pressure switch closed, and A/C request OFF: battery voltage. When A/C request switches ON, voltage changes to about 0 V.
13BLU/YELBLW-GPower transistor control outputWith ignition switch ON (II) and blower OFF: 0 V. Voltage increases as blower speed increases
15GRN/WHTFRSDrives the recirculation control motor to FRESHWith ignition switch ON (II) with motor moving to FRESH: battery voltage
16GRN/YELRECDrives the recirculation control motor to RECWith ignition switch ON (II) with motor moving to REC: battery voltage
21YELMODE 4Mode control motor signal 4With ignition switch ON (II) about 5 V or about 0 V, depending upon mode
22BLK/WHTMODE 3Mode control motor signal 3With ignition switch ON (II) about 5 V or about 0 V, depending upon mode
23BLK/WHTIllumination cancel signal from gauge control module
26BLKGNDGround for heater control panelLess than 0.5 V at all times
27RED/BLKILL+Power source for illuminationWith ignition switch ON (II): battery voltage
28REDILLGround for illuminationWith combination light switch ON: voltage decreases as dash light brightness increases
29WHT/RED+BBattery power sourceBattery voltage at all times
30BLK/YELIG2IG2 power sourceWith ignition switch ON (II): battery voltage

HVAC CONTROL UNIT REFERENCE

Scheme 7

Scheme 7: Circuit Diagram
Scheme 7: Circuit Diagram

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Scheme 8

Scheme 9

Scheme 9: DTC 1: A Problem in the Air Mix Control Motor Circuit
Scheme 9: DTC 1: A Problem in the Air Mix Control Motor Circuit

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Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11
  1. Disconnect the air mix control motor 7P connector.
  2. Test the air mix control motor (see «AIR MIX CONTROL MOTOR TEST»(ref-277065-S34311177842008011500000) ). Is the air mix control motor OK? YES -Go to step 3. NO -Go to step 7 .
  3. Disconnect the HVAC control unit 30P connector.
  4. Check for continuity between body ground and HVAC control unit 30P connector terminals No. 1,2, 5,6, and 10 individually. Is there continuity? YES -Repair short to body ground in the wire(s) between the HVAC control unit and the air mix control motor. NO -Go to step 5.
  5. Turn the ignition switch to ON (II), and measure the voltage between the same terminals and body ground. Is there any voltage? YES -Repair short to power in the wire(s) between the HVAC control unit and the air mix control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the HVAC control unit. NO -Go to step 6.
  6. Turn the ignition switch to LOCK (0), and check for continuity between the following terminals of the HVAC control unit 30P connector and the air mix control motor 7P connector. 30 Pin 7 Pin 1 2 2 1 5 5 6 3 10 7 Is there continuity? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector, and at the air mix control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit. NO -Repair open in the wire(s) between the HVAC control unit and the air mix control motor.
  7. Remove the air mix control motor (see «AIR MIX CONTROL MOTOR REPLACEMENT»(ref-277065-S02876749892008011500000) ).
  8. Check the air mix control linkage and doors for smooth movement. Do the air mix control linkage and doors move smoothly? YES -Replace the air mix control motor. NO -Repair the air mix control linkage or doors.

Scheme 12

Scheme 12: DTC 2: A Problem in the Mode Control Motor Circuit
Scheme 12: DTC 2: A Problem in the Mode Control Motor Circuit

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Scheme 13
Scheme 13

Scheme 14

Scheme 14
Scheme 14
  1. Disconnect the mode control motor 7P connector.
  2. Test the mode control motor (see «MODE CONTROL MOTOR TEST»(ref-277065-S12543417172008011500000) ). Is the mode control motor OK? YES -Go to step 3. NO -Go to step 7 .
  3. Disconnect the HVAC control unit 30P connector.
  4. Check for continuity between body ground and HVAC control unit 30P connector terminals No. 3, 4, 8, 9, 10, 21, and 22 individually. Is there continuity? YES -Repair short to body ground in the wire(s) between the HVAC control unit and the mode control motor. NO -Go to step 5.
  5. Turn the ignition switch to ON (II), and measure the voltage between the same terminals and body ground. Is there any voltage? YES -Repair short to power in the wire(s) between the HVAC control unit and the mode control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the HVAC control unit. NO -Go to step 6.
  6. Turn the ignition switch to LOCK (0), and check for continuity between the following terminals of the HVAC control unit 30P connector and the mode control motor 7P connector. 30 Pin 7 Pin 3 2 4 1 8 5 9 6 10 7 21 3 22 4 Is there continuity? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector and at the mode control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/ indication goes away, replace the original HVAC control unit. NO -Repair open in the wire(s) between the HVAC control unit and mode control motor.
  7. Remove the mode control motor (see «MODE CONTROL MOTOR REPLACEMENT»(ref-277065-S20487744622008011500000) ).
  8. Check the mode control linkage and doors for smooth movement. Do the mode control linkage and doors move smoothly? YES -Replace the mode control motor. NO -Repair the mode control linkage or doors.

Scheme 15

Scheme 15: DTC 3: A Problem in the Blower Motor Circuit
Scheme 15: DTC 3: A Problem in the Blower Motor Circuit

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Scheme 23
  1. Check the No. 56(40 A) fuse in the main under-hood fuse/relay box, and the No. 20 (7.5 A) fuse in the under-dash fuse/relay box. Are the fuses OK? YES -Go to step 2. NO -Replace the fuse(s), and recheck. If the fuse(s) blow again, check for a short in the No. 56 (40 A) and the No. 20 (7.5 A) fuse circuits.
  2. Connect blower motor 2P connector terminal No. 2 to body ground with a jumper wire.
  3. Turn the ignition switch to ON (II). Does the blower motor run? YES -Go to step 4. NO -Go to step 17 .
  4. Turn the ignition switch to LOCK (0).
  5. Disconnect the jumper wire.
  6. Disconnect the power transistor 5P connector.
  7. Check for continuity between power transistor 5P connector terminal No. 5 and body ground. Is there continuity? YES -Go to step 8. NO -Check for an open in the wire between the power transistor and body ground. If the wire is OK, check for poor body ground at G402 (see «CONNECTOR TO HARNESS INDEX»(ref-221381-S31007361512006022400000) ).
  8. Connect power transistor 5P connector terminals No. 4 and No. 5 with a jumper wire.
  9. Turn the ignition switch to ON (II). Does the blower motor run at high speed? YES -Go to step 10. NO -Repair open in the wire between the power transistor and the blower motor.
  10. Turn the ignition switch to LOCK (0).
  11. Disconnect the jumper wire.
  12. Disconnect the HVAC control unit 30P connector.
  13. Check for continuity between HVAC control unit 30P connector terminals No. 11 and No. 13 and body ground individually. Is there continuity? YES -Repair short to body ground in the wire(s) between the HVAC control unit and the power transistor. NO -Go to step 14.
  14. Check for continuity between the following terminals of the HVAC control unit 30P connector and the power transistor 5P connector. 30 Pin 5 Pin 11 1 13 3 Is there continuity? YES -Go to step 15. NO -Repair open in the wire(s) between the HVAC control unit and the power transistor.
  15. Reconnect the HVAC control unit 30P connector.
  16. Test the power transistor (see «POWER TRANSISTOR TEST»(ref-277065-S42478626942008011500000) ). Is the power transistor OK? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector, the blower motor 2P connector, and at the power transistor 5P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit. NO -Replace the power transistor.
  17. Disconnect the jumper wire.
  18. Disconnect the blower motor 2P connector.
  19. Measure the voltage between blower motor 2P connector terminal No. 1 and body ground. Is there battery voltage? YES -Replace the blower motor. NO -Go to step 20.
  20. Turn the ignition switch to LOCK (0).
  21. Remove the blower motor relay from the main under-hood fuse/relay box, and test it (see «MAIN UNDER-HOOD FUSE/RELAY BOX»(/honda/s2000/ap1-1999-2003/remont/body-electrical/#fuserelay-boxes__main-under-hood-fuserelay-box) ). Is the relay OK? YES -Go to step 22. NO -Replace the blower motor relay.
  22. Measure the voltage between blower motor relay 4P socket terminal No. 4 and body ground. Is there battery voltage? YES -Go to step 23. NO -Replace the main under-hood fuse/relay box (see «MAIN UNDER-HOOD FUSE/RELAY BOX»(/honda/s2000/ap1-1999-2003/remont/body-electrical/#fuserelay-boxes__main-under-hood-fuserelay-box) ).
  23. Turn the ignition switch to ON (II).
  24. Measure the voltage between blower motor relay 4P socket terminal No. 1 and body ground. Is there battery voltage? YES -Go to step 25. NO -Repair open in the wire between the No. 20 (7.5 A) fuse in the under-dash fuse/relay box and the blower motor relay.
  25. Turn the ignition switch to LOCK (0).
  26. Check for continuity between blower motor relay 4P socket terminal No. 2 and body ground. Is there continuity? YES -Repair open in the wire between the blower motor relay and the blower motor. NO -Check for an open in the wire between the blower motor relay and body ground. If the wire is OK, check for poor body ground at G201 (see «CONNECTOR TO HARNESS INDEX»(ref-221381-S31007361512006022400000) ).

Scheme 24

Scheme 24: DTC 4: A Problem in the Evaporator Temperature Sensor Circuit
Scheme 24: DTC 4: A Problem in the Evaporator Temperature Sensor Circuit

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Scheme 28
  1. Disconnect the evaporator temperature sensor 2P connector.
  2. Measure the resistance between evaporator temperature sensor terminals No. 1 and No. 2. Is the resistance within the specifications shown on the graph? YES -Go to step 3. NO -Replace the evaporator temperature sensor (see «BLOWER/EVAPORATOR UNIT REMOVAL/INSTALLATION»(ref-351955-S31936470922009122900000) ).
  3. Disconnect the HVAC control unit 30P connector.
  4. Check for continuity between HVAC control unit 30P connector terminal No. 7 and body ground. Is there continuity? YES -Repair short to body ground in the wire between the HVAC control unit and the evaporator temperature sensor. NO -Go to step 5.
  5. Check for continuity between HVAC control unit 30P connector terminal No. 7 and evaporator temperature sensor 2P connector terminal No. 2. Is there continuity? YES -Go to step 6. NO -Repair open in the wire between the HVAC control unit and the evaporator temperature sensor.
  6. Check for continuity between HVAC control unit 30P connector terminal No. 10 and evaporator temperature sensor 2P connector terminal No. 1. Is there continuity? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector, and at the evaporator temperature sensor 2P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/ indication goes away, replace the original HVAC control unit. NO -Repair open in the wire between the HVAC control unit and the evaporator temperature sensor.

Scheme 29

Scheme 29: Recirculation Control Motor Circuit Troubleshooting
Scheme 29: Recirculation Control Motor Circuit Troubleshooting

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Scheme 30

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Scheme 32
Scheme 32
  1. Check the No. 20 (7.5 A) fuse in the under-dash fuse/relay box. Is the fuse OK? YES -Go to step 2. NO -Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 20 (7.5 A) fuse circuit.
  2. Disconnect the recirculation control motor 7P connector.
  3. Turn the ignition switch to ON (II).
  4. Measure the voltage between recirculation control motor 7P connector terminal No. 1 and body ground. Is there battery voltage? YES -Go to step 5. NO -Repair open in the wire between the No. 20 (7.5 A) fuse in the under-dash fuse/relay box and the recirculation control motor.
  5. Turn the ignition switch to LOCK (0).
  6. Test the recirculation control motor (see «RECIRCULATION CONTROL MOTOR CIRCUIT TROUBLESHOOTING»(ref-277065-S31807821192008011500000) ). Is the recirculation control motor OK? YES -Go to step 7. NO -Go to step 11 .
  7. Disconnect the HVAC control unit 30P connector.
  8. Check for continuity between HVAC control unit 30P connector terminals No. 15 and No. 16 and body ground individually. Is there continuity? YES -Repair short to body ground in the wire(s) between the HVAC control unit and the recirculation control motor. NO -Go to step 9.
  9. Turn the ignition switch to ON (II), and measure the voltage between the same terminals and body ground. Is there any voltage? YES -Repair short to power in the wire(s) between the HVAC control unit and the recirculation control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the HVAC control unit. NO -Go to step 10.
  10. Turn the ignition switch to LOCK (0), and check for continuity between the following terminals of the HVAC control unit 30P connector and the recirculation control motor 7P connector. 30 Pin 7 Pin 15 5 16 7 Is there continuity? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector, and at the recirculation control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/ indication goes away, replace the original HVAC control unit. NO -Repair open in the wire(s) between the HVAC control unit and the recirculation control motor.
  11. Remove the recirculation control motor (see «RECIRCULATION CONTROL MOTOR REPLACEMENT»(ref-277065-S33450122292008011500000) ).
  12. Check the recirculation control linkage and doors for smooth movement. Do the recirculation control linkage and doors move smoothly? YES -Replace the recirculation control motor. NO -Repair the recirculation control linkage or doors.

Scheme 33

Scheme 33: HVAC Control Power and Ground Circuit Troubleshooting
Scheme 33: HVAC Control Power and Ground Circuit Troubleshooting

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Scheme 35
  1. Check the No. 54 (30 A) fuse in the main under-hood fuse/relay box, and the No. 20 (7.5 A) and No. 25 (7.5 A) fuses in the under-dash fuse/ relay box. Are the fuses OK? YES -Go to step 2. NO -Replace the fuse(s), and recheck. If the fuse(s) blow again, check for a short in the No. 54 (30 A), the No. 20 (7.5 A), and the No. 25 (7.5 A) fuse circuits.
  2. Disconnect the HVAC control unit 30P connector.
  3. Turn the ignition switch to ON (II).
  4. Measure the voltage between HVAC control unit 30P connector terminal No. 30 and body ground. Is there battery voltage? YES -Go to step 5. NO -Repair open in the wire between the No. 20 (7.5 A) fuse in the under-dash fuse/relay box and the HVAC control unit.
  5. Turn the ignition switch to LOCK (0).
  6. Measure the voltage between HVAC control unit 30P connector terminal No. 29 and body ground. Is there battery voltage? YES -Go to step 7. NO -Repair open in the wire between the No. 25 (7.5 A) fuse in the under-dash fuse/relay box and the HVAC control unit.
  7. Check for continuity between HVAC control unit 30P connector terminal No. 26 and body ground. Is there continuity? YES -Check for loose wires or poor connections at the HVAC control unit 30P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/ indication goes away, replace the original HVAC control unit. NO -Check for an open in the wire between the HVAC control unit and body ground. If the wire is OK, check for poor body ground at G402 (see «CONNECTOR TO HARNESS INDEX»(ref-221381-S31007361512006022400000) ).

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