wasin105

I got a 2004 civic hybrid . Long story short, compressor wouldn't start when pressing the A/C button(button lights up).
1. I started check all the fuses under the hood and under dash board( no blown fuse). Next I checked the relay by pull out and energized 12V DC (all of them is work too).
2. Second I disconnect the thermo protector and verified continuty. Do the same on the a/c pressure switch too. Thermo protector and a/c pressure switch is good and having a voltage about 5 VDC.
3. And then I checked the wire between the batt to fuse, fuse to ac clutch relay(all wires is not broken), From relay #2(a/c clutch relay) I think and checked relay#2 coil is getting 12VDC on pin 3(reference to body ground) but if I check voltage drop between Pin 3 and 4(3,4 is coil 12 VDC) on relay#2 ,it drops to 0.5VDC. I look into the 2004 honda fix circuit and it gets the ground from ECM pin E18.

4. So I bypass a/c compressor by disconnect all wire that run back to ECM and compressor and compressuor clutch worked . The ac works perfect super cold in minutes.
Any suggestions? please help. Thanks in advance
5. Someone said check the ground but i do not know what he means check the ground at CCU or ground at ECM? And How to check too?


My ground to the compressor clutch is intact.

TIA everyone!

ezone

When you turn on the AC button, do the radiator fans kick on?

wasin105

MY car have two fans.
1. Condenser fan is on.
2. Radiator fan is off but when the engine is hot the radiator fan is on.

ezone

According to my wiring diagram, the PCM can turn on just the radiator fan during a hot restart, but under most other conditions the systems run both fans together.

When the AC operates correctly, both radiator fans are supposed to be on at the same time.


This was with the engine running and AC system turned on and all wiring connected?


If you backprobe the connector terminals in the thermal protector OR the pressure safety switch, what reading do you get? 12v, 5v, 0v, or ground?

(assuming it's 5v for now)

Do you have the section of wire diagram showing the rest of the circuit that runs to the pressure switch, thermal protector, PCM...showing the HVAC control panel?

ezone

Does the interior blower fan operate?

ezone

Have you made the HVAC panel do its self diagnosis tests?

wasin105

1. Yes I just looked at the wiring diagram the PCM can turn on the radiator fan relay coil and the compressor relay coil in the same time but my radiator fan will work went the thrmo stat in the cooling system is on, under most other conditions the systems should run both fans together when certain temp is reach.

2.This was with the engine running and AC system turned on and all wiring connected? Yes everything is on and connected.

3.This was with the engine running and AC system turned on and all wiring connected? Yes it is 4.96VDC backprob at ac pressure sw and thermo protector( reference to ground)

TIA ezone

wasin105

I do not know how to? But I did use the temperature **** to control the temp after I bypass the ac compressor clutch and I it seem fine( i put the fan in auto mode), when I turn to increase the temp the compressor have too much pressure and relief to the relief valve.
And when I turned to heat at 82 F is working fine.

ezone

The circuit you show 5v on is supposed to be grounded.
Now you need to see why there is no grounding from the HVAC panel....

Start with answering these questions:



EDIT: I guess the fan works.

wasin105

Yes the interior blower fan is working too.

wasin105

Someone on another post said , I need a snap on OBO reading ($8000 one) to read the error code on the ac. But I went to talk to the mechanic on post who has the $8000 scanner, he said the scanner will not tell anything about ac. I have on that China made $30. LOL
Any suggestion?
TIA

ezone

A good service manual is of more value.

ezone

Key OFF
fan switch OFF
push and hold econ and recirc buttons
turn key ON (do not start the engine)
release econ and recirc buttons

recirc light comes on for 2 seconds, goes out, ac light comes on
self test begins
wait about 10 seconds, ac light turns off

recirc light blinks fault code if a fault is present

wasin105

I did like you recommend( just read in the manual too LOL) but No code or blink.
But I found another way to read the code ( I am not sure is this way tell me some code)
Key OFF
fan switch OFF
push and hold AC and recirc buttons
turn key ON (do not start the engine)
Hold on AC and recirc buttons and waiting until hearing on kick sound from the dash board.( like do normal HVAC read code sound)

After that I got recic LED blink six times( in manual said for code#6 A short in the sunliqht sensor circuit)

OR
Key OFF
fan switch OFF
push and hold AC and ECON buttons
turn key ON (do not start the engine)
Hold on AC and ECON buttons and waiting until hearing on kick sound from the dash board.( like do normal HVAC read code sound)

After that I got AC LED blink six times too at this time( in manual said for code#6 A short in the sunliqht sensor circuit)

ezone

There are a few variations of the test for different cars. I was reading mine from the hybrid service info online.

I think if there is not sunlight when you do the test that code will set.
I know it will set on most of the cars when done in the shop under fluorescent lights.

IMO Next steps would be to

A) make sure the system will run when the pressure switch-thermal protector circuit is grounded (use a jumper wire to supply ground to the pressure switch wiring)

B) then verify the HVAC control panel is not grounding the circuit, rule out a wire problem between those points

Check your wire diagram, I think it was the blue wire on pin 6 in the hvac panel on the dash?


I know the panel can be a problem on regular 7th gen Civics, but I don't remember having to figure it out on a hybrid car.

wasin105

Thank you . I will check the blue wire tomorrow.