jerseykid418

So I'm having issues with my A/C compressor in my 2004 honda civic. When the car is still and the A/C button is turned off the compressor will kick in. It won't stay on but its not turning on and off constantly either. But when i turn the A/C button on, the compressor won't kick in at all. Even if the clutch kicked in while the button is off, when i turn the button on the compressor will stop. Also if the button is off and the compressor kicks in, if i step on the gas pedal a little the compressor will turn off. I have no idea what's wrong with this. Some help will be greatly appreciated.

ezone

Can't lie, that sounds weird and unusual.

When the AC compressor randomly kicks on, do the radiator fans also turn on at the same time?

I'd plug in my scanner to see if the PCM sees an AC request signal when it should not. Then decide the next move.

Got any water in the drivers floorboard?
Other unusual electrical problems, like door ajar and headlight reminder warning beeper inop, entry lighting inop, etc?

jerseykid418

Yes the fan does turn on and off with the compressor. And no I haven't had any other electrical issues with the car

ezone

Make SURE you haven't set the HVAC control **** in any of the defrost positions..because it will run the AC system without turning the indicator light on in all defrost positions.


Ok....fans and compressor turn on together.....Means an AC request is being made to the PCM and the PCM is turning the system on.

First off, this AC system and both radiator fans are controlled by the engine control unit (PCM). When you work the buttons on the dash, the HVAC control panel sends a request signal to the MICU (body systems control unit) which goes to the PCM, and the PCM checks out several things and makes sure it's OK to let the AC operate....and turns the compressor and fans on if it decides it's OK.



Now I want to figure out 2 things:
1) If the HVAC control panel is telling the system to turn on at the wrong time....or
2) if the request signal wire has been grounded somewhere between the panel and the MICU.

This request line is one circuit (out of about 35 wires) on the back of the HVAC panel.... it runs from the HVAC panel to the pressure cutout switch on the receiver-drier, then to the thermal protector on the compressor housing, and back to the fusebox (MICU) inside the car.

So first I'd look for anyplace the wire harnesses carrying that circuit might be damaged or have exposed wires first.....because if this circuit is grounded anywhere the AC system will be turned on by the PCM.

Then if nothing was found that way.....what I would probably want to do is get it to act up (run the AC when it should not), then remove and disconnect the 14 cavity plug from the control panel (the control unit is behind the row of dials, not the 3 switches at the bottom).

If that makes the AC system turn off, the problem is in the control panel.
If the AC system keeps running, then we start checking if the blue wire in cavity A4 is grounded, and figure out why and where it is grounded (probably in the engine compartment, again checking wiring leading to the pressure switch and the compressor and the harnesses that lead to those items and the larger harnesses that lead into and out of the interior)
So....next unplug the pressure switch and see if the compressor stops.
Then you'd have to figure from there where the circuit got grounded.

Google came up with a generic AC diagram, I'm not positive this matches the car you have, but the parts I looked at are pretty close (circuit from panel #A4 to pressure switch to thermal protector to MICU)

http://ww2.justanswer.com/uploads/ya...it_diagram.gif