 Show Join Date: May 2008 Posts: 12 Hello! I've been reading in this forum for awhile now and had to register today so I could ask for advice. My civic's A/C starting working intermittantly last summer. I took it to have it vacuumed out and then recharged andsince that point it hasn't worked at all. I bought a spare compressor and when I hook it up outside of the car, the cooling fans come on just like they should, only they come on whether the AC is on or off. I disconnect the spare andfans shut back off.I jumpered the thermal switch on the compressor still in the car and the clutch/cooling fanskick on and the AC gets ice cold very quick. I could leave it this way, only the clutch stays engaged all the time, even if the AC is turned off. Without this jumpered, the clutch/cooling fans won't come on with the AC at all. My theory is that something is keepingpower going to the clutch all the timewhich in turnburned out the thermal switch sometime last year leaving me with 2 issues. I'm opento any and all suggestions as I have an appointment with a honda dealer this wednesday and am trying everything to prevent this very expensive option. Thanks!Matt Join Date: Sep 2007 Location: Houston, Texas Posts: 9,453 Unhook the new external compressor to bring system back to stock. Then, see if you can retrieve a DTC: (Edit: Are either fuse 1 or fuse 14 blown? Have you tested the compressor clutch relay?)
Join Date: May 2008 Posts: 12 I checked and just rechecked all fuses and relays in the system and all are in working condition. I ran the diagnostic and had no flashing light to indicate any problems. Join Date: Sep 2007 Location: Houston, Texas Posts: 9,453 Why don't you think that the problem will be fixed by replacing the thermal protector? Why not try swapping the thermal protector in the old compressor with the one in the new compressor? Join Date: May 2008 Posts: 12 Before I replace the thermal protector, I want to fix the issue of the AC staying on all the time. As I mentioned before, when I plug the other compressor in, the AC gets power all the time, even if the AC is shut off which is the same as the compressor thats currently in it with the jumpered
thermal protector. I know the thermal protector isone of the issues, trying figure out why the compressor clutch is engaged all the timeand not with the AC switch. Join Date: Sep 2007 Location: Houston, Texas Posts: 9,453 Does the A/C run independently of the blower motor? Look for a shorted/damaged wire between the ECM and heater control panel:
Join Date: Jun 2007 Posts: 10,023 It's OK to jumper the thermal switch for testing purposes. I think Ron's diagram isn't exactly what you have. Some models have the thermal switch connected directly to the clutch as shown and others have low-level wires that go into the control system from the thermal switch. When you have that latter system and there is a short to ground in the thermal switch or it's wiring the compressor and fans will stay on all the time. The way it works is the A/C control panel pulls the blue wire on pin 4 to ground to demand A/C (control panel checks that interior fan on, driver has pressed the A/C button, and the evaporator temperature is above 40 F). This signal passes thru the thermal switch and the pressure switch to the multiplex control unit. The multiplex control unit sends a command to the ECM. If the engine is running at a proper RPM, the ECM then closes the compressor and fan relays. Check for shorts to ground on the wire between the control panel, switches, and multiplex control unit. If you can unplug the control panel (disconnect battery first since there is a computer in it) and the A/C stops, the control panel may be bad. Join Date: Sep 2007 Location: Houston, Texas Posts: 9,453 Quote: ORIGINAL: mk378 The diagrams were taken from the 02-03 Civic service manual: http://hondatech.info/downloads/Auto/Manuals/Civic/ The same manual shows the thermal switch associated with the compressor:
Join Date: May 2008 Posts: 12 I made the appointment for tomorrow, I will post back tomorrow with the results. I
have a feeling it's either the ECM or the multiplex unit itself. Thanks for all of the replies and suggestions! Join Date: May 2008 Posts: 12 One more question just to make sure I jumpered the thermal protector correctly. I hooked the 2 wires together that are not the clutch power wire. When I hook these together, the middle wire gets 12V positive and the clutch engages. Thanks again. Why isn't my compressor turning on in my car?If the AC compressor doesn't turn on, the most common culprit by far is low AC refrigerant. If there is a leak, no matter how small, it'll eventually cause a non-working AC system. Another possible issue is a blown fuse and/or relay. Your owner's manual should be able to tell you where those are located.
Why is my AC clutch not coming on?If the clutch doesn't engage, the problem could be a blown fuse, an open in the wire to the clutch coil, a bad clutch coil, a poor ground, or a low pressure lockout. In some vehicles the compressor clutch relay is turned on and off by the low pressure switch and the evaporator temperature sensor.
How do I manually start my AC compressor?At the compressor's front side, unplug the single wire connector, take a jumper wire and attach it to the wire that you just disconnected from the compressor. Connect the other end of the jumper's wire to the positive terminal of the car battery. This will enable the compressor to start manually.
Can a fuse stop the AC compressor from working?It is possible that when the fuse of AC has blown, it can cause the entire system and functioning of AC to shut down because it cannot initiate cooling anymore.
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2002 honda civic ac compressor not turning on
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