95 Accord LX 2.2 (Idle drops way too much when cooling fan kicks in)
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Joined: May 2008
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Got your PM. Here's what I suspected earlier:
Compressor engages because it get's a ground signal to the AC compressor relay. Why? The ECU thinks the AC is commanded On. You have to find the false ground that is causing that signal.
From what you've posted, the AC Switch (dash panel switch) has been disconnected, and still the AC compressor engages. That means there is a ground somewhere on the Red/Wht wire possibly near where red/wht ties to ECU input. I believe the tie-pt between red/wht wire to ECU and diode must be near the diode under the hood. Note, this wire would run all the way back to the ECU under the passenger's foot area, so there are many places where an accidental or deliberate short could be introduced.
I'm not absolutely sure of above, because much earlier you posted that Red/Wht had 12V, which is what it should have if NO ground is available. Only when ground occurs through normal path (AC thermostat, panel switch, and blower fan switch (On) should ground pull the red/wht to ground and send signal to the ECU to command compressor.
I assume you have the wiring diagram to check and be sure you understand.
Another possibility is a sticking AC compressor relay. Once closed the contacts weld closed and compressor will always run when keyswitch is ON. Verify that AC relay opens when keyswitch is turned to OFF.
good luck
Compressor engages because it get's a ground signal to the AC compressor relay. Why? The ECU thinks the AC is commanded On. You have to find the false ground that is causing that signal.
From what you've posted, the AC Switch (dash panel switch) has been disconnected, and still the AC compressor engages. That means there is a ground somewhere on the Red/Wht wire possibly near where red/wht ties to ECU input. I believe the tie-pt between red/wht wire to ECU and diode must be near the diode under the hood. Note, this wire would run all the way back to the ECU under the passenger's foot area, so there are many places where an accidental or deliberate short could be introduced.
I'm not absolutely sure of above, because much earlier you posted that Red/Wht had 12V, which is what it should have if NO ground is available. Only when ground occurs through normal path (AC thermostat, panel switch, and blower fan switch (On) should ground pull the red/wht to ground and send signal to the ECU to command compressor.
I assume you have the wiring diagram to check and be sure you understand.
Another possibility is a sticking AC compressor relay. Once closed the contacts weld closed and compressor will always run when keyswitch is ON. Verify that AC relay opens when keyswitch is turned to OFF.
good luck
This is by far the most frustrating issue I have even had with a car.
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Joined: Sep 2006
Posts: 16,329
From: Houston, TX
The red/blu wire goes to the ECU. I noticed that TCU is listed under ECM (A15 ACC) in that manual.
I just looked at my shop manual and it looks like the red/blu wire also goes to TCU pin A22. Look at page 14-22 of that shop manual that you downloaded.
I just looked at my shop manual and it looks like the red/blu wire also goes to TCU pin A22. Look at page 14-22 of that shop manual that you downloaded.
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So does that mean theres a chance its the TCU? Because if so Im sure the same guy I got the ECU from would give me a break on the price.
Super Moderator : And A Texan
Joined: Feb 2007
Posts: 9,652
From: Katy, TX
The ground signal feed (Red/Wht) to the ECM (B5 ACS) is schematically depicted along side the ECM ground (red/blu) from (A15 ACC), although these are different connectors to the ECM.
The Red/Blu ground to the compressor clutch relay apparently is also connected to the TCM (2nd bullet point on wiring diagram). This signal may be used by TCM to cause shift point changes w/ AC load on engine.
good luck
The Red/Blu ground to the compressor clutch relay apparently is also connected to the TCM (2nd bullet point on wiring diagram). This signal may be used by TCM to cause shift point changes w/ AC load on engine.
good luck
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Joined: May 2010
Posts: 11,834
From: Kenton, TN
I only brought up the red/blu from the TCU as another source of the ground. Been following this, finally last night (what else is there to do on a Friday night) spent a fair amount of time looking thru the diagrams...scratching my head like everyone else. It was about the only thing that has not been tested or talked about.
If the ac relay was stuck closed, the compressor would be on all the time as the wht wire is hot at all times (fuse 34).
Sorry for jumping in.
If the ac relay was stuck closed, the compressor would be on all the time as the wht wire is hot at all times (fuse 34).
Sorry for jumping in.
Thread Starter
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Member
Joined: May 2008
Posts: 97
From:
I only brought up the red/blu from the TCU as another source of the ground. Been following this, finally last night (what else is there to do on a Friday night) spent a fair amount of time looking thru the diagrams...scratching my head like everyone else. It was about the only thing that has not been tested or talked about.
If the ac relay was stuck closed, the compressor would be on all the time as the wht wire is hot at all times (fuse 34).
Sorry for jumping in.
If the ac relay was stuck closed, the compressor would be on all the time as the wht wire is hot at all times (fuse 34).
Sorry for jumping in.
Super Moderator
Joined: May 2010
Posts: 11,834
From: Kenton, TN
TX-Ok, as with everyone else-trying to find the source of what is gounding the red/blu wire when it should not be.
In post 16 you jump Thermo A on t-stat housing and only the "right" fan came on. First, is this the right/pass side fan-known as cooling fan- or was it the left/drivers side fan-known as condensor fan.
EDIT: Might see if you car has had this repair/recall done?? Again looking for any ideas, this came to me a few minutes ago:
Honda Motor Co., Ltd. has decided that a defect which relates to motor vehicle safety exists in certain 1995 - 97 Accords. The factory-installed air conditioner wire harness in certain 1995 - 97 Accords may have been improperly routed, allowing some wires to rub against each other. Eventually, the insulation covering the wires may wear through and possibly cause a short circuit. This problem is usually detected by a blown fuse, a dead battery, or a malfunction of the air conditioner. A short circuit could also cause the under-hood wiring to overheat and smoke. In the worst case, a short circuit could cause a fire in the engine compartment.
In post 16 you jump Thermo A on t-stat housing and only the "right" fan came on. First, is this the right/pass side fan-known as cooling fan- or was it the left/drivers side fan-known as condensor fan.
EDIT: Might see if you car has had this repair/recall done?? Again looking for any ideas, this came to me a few minutes ago:
Honda Motor Co., Ltd. has decided that a defect which relates to motor vehicle safety exists in certain 1995 - 97 Accords. The factory-installed air conditioner wire harness in certain 1995 - 97 Accords may have been improperly routed, allowing some wires to rub against each other. Eventually, the insulation covering the wires may wear through and possibly cause a short circuit. This problem is usually detected by a blown fuse, a dead battery, or a malfunction of the air conditioner. A short circuit could also cause the under-hood wiring to overheat and smoke. In the worst case, a short circuit could cause a fire in the engine compartment.
Last edited by poorman212; Apr 9, 2011 at 10:59 AM.
Super Moderator : And A Texan
Joined: Feb 2007
Posts: 9,652
From: Katy, TX
What do you get if you pull the AC compressor relay and check pin that has the red/blue wire for connection to ground. Does it show a ground all the time, keysitch on, engine running?
good luck
good luck