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Thread: Lost my AC idle boost

  1. #1


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    Lost my AC idle boost

    It seems in the last week or so of letting my wife borrow my car I don't get the idle boost that I usually get with the AC on. Few times I noticed this weekend,at stoplights, that it nearly stalled and the idle is pretty low. I tried it in the garage and the idle seems uneffected by putting the AC on/off. I'm used to a nice idle just under 1000 rpm with the AC on. The AC off idle has always been a little more bouncy.

    Any ideas?


    wp
    1988 Lxi owner since August 1995
    336k miles running strong!
    Now running E85.

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  2. #2

    2oodoor's Avatar
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    Re: Lost my AC idle boost

    clean the throttle body
    check the ac idle boost thing over on the driver side fender, I havent messed with those much but I assume it works off the ac clutch relay also it does have an adjustment on it

  3. #3

    Dr_Snooz's Avatar
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    Re: Lost my AC idle boost

    How low is "pretty low"? If you lost boost, then it would be somewhere around 200 rpm and on the verge of dying. If you're just noticing some roughness at lights, then it might be time for some Techron or a tune up. If it is the AC boost, then given the intermittent nature, I'd be looking at the idle boost solenoid valve, which is electrically controlled. The diaphragm itself might also have sprung a leak. Worth a check with the vacuum pump.
    Last edited by Dr_Snooz; 07-03-2011 at 12:57 PM.
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


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  4. #4


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    Re: Lost my AC idle boost

    I m running on a 3rd day migraine so forgive me. The idle is low maybe 500 rpm. Just when you push the clutch in at a stop sign it recovers but the car shakes for a few seconds. Usually with the air on its about 950-1000 on the stock tach.

    I cleaned out the TB didn't look to bad. When I get a chance ill clean the K=N cone i have on there. I need the car up a few more days. Wiring as far as I can tell looks ok.


    Everything else seems fine. I just got 29.5 mpg on the last tank.


    I am thinking the EACV is what boost the idle a little?

    wp
    1988 Lxi owner since August 1995
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    Now running E85.

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  5. #5

    carotman's Avatar
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    Re: Lost my AC idle boost

    You have an 88-89 LX-i so the only thing boosting the idle is indeed the EACV.

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  6. #6

    2oodoor's Avatar
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    Re: Lost my AC idle boost

    Quote Originally Posted by carotman View Post
    You have an 88-89 LX-i so the only thing boosting the idle is indeed the EACV.
    ahh! didn't know that...

    and ole blue I hope you feel better, I have been getting a few signs of trying to get one myself this past two weeks. Ive only have like four in my whole life and I know that feeling well just the same.

    I would want to check the timing at idle to see if the vac advance is intermitantly working as well but I guess you would feel that without ac on but maybe not with a five speed it may be subtle.

  7. #7

    Dr_Snooz's Avatar
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    Re: Lost my AC idle boost

    Quote Originally Posted by carotman View Post
    You have an 88-89 LX-i so the only thing boosting the idle is indeed the EACV.
    News to me too. The manual shows a diaphragm and a solenoid, so I assumed there was one. Yeah, good luck with that one Blue.

    For what it's worth, I have read that feverfew taken consistently will reduce or eliminate migraines.
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


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  8. #8
    LXi User ecogabriel's Avatar
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    Re: Lost my AC idle boost

    Quote Originally Posted by Dr_Snooz View Post
    News to me too. The manual shows a diaphragm and a solenoid, so I assumed there was one. Yeah, good luck with that one Blue.

    For what it's worth, I have read that feverfew taken consistently will reduce or eliminate migraines.
    Ditto on the solenoid and diaphragm; you snooz have the '89 manual right? (yeah, I bet you do)

    A/C idle boost was dead on my '86; solenoid was dead. Replaced solenoid with a jy unit and it now works. You may get a used one from the jy but take a multimeter with you to check continuity between the contacts; if there is continuity it most likely work.

    I have one or two solenoid spares if you do not have one and need one.

    I dunno what is good for headaches, but if yours is bad and lasts a few days I would suggest a visit to the doctor or at least get your blood pressure tested. Hope you get better
    If it ain't broke... I fix it!

  9. #9


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    Re: Lost my AC idle boost

    Well small update:

    Me: Dr says I have Cluster Headaches.Great.Prednisone and he told me to try Imitrex too.

    Car:

    Well something I can fix.

    Page 12-48 of the 1988 manual says I need less than 3 volts measuring from B8+ to A18- with the AC on. If not look for a break from the AC diode connector which atm I can seem to find. p. 26-9 list it as C-42 4 pin but I cant seem to find it in the drawing for the FI car. Thinking I could test it there easier than back probing the ECU connector. I don't have there beloved test harness. And anyway yesterday its working and the idle is locked on with the AC on. So will do some testing when I feel a little better.

    Thanks for all the help.


    wp
    1988 Lxi owner since August 1995
    336k miles running strong!
    Now running E85.

    Oldblueaccord <<< MY YOUTUBE PAGE!

  10. #10

    Dr_Snooz's Avatar
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    Re: Lost my AC idle boost

    The Electrical Troubleshooting Manual should show the location of the diode on p. 206.

    Instead of the test harness, can you plug your multimeter probes into the back of the ECU connector?

    Hope you get to feeling better soon.
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


    1989 Honda Accord LX-i Coupe, 240k miles, MT swap, rear disc swap

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  11. #11
    LXi User ecogabriel's Avatar
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    Re: Lost my AC idle boost

    Quote Originally Posted by Dr_Snooz View Post
    The Electrical Troubleshooting Manual should show the location of the diode on p. 206.

    Instead of the test harness, can you plug your multimeter probes into the back of the ECU connector?

    Hope you get to feeling better soon.
    Ditto. If it now works, I suspect there may be a corroded terminal somewhere. The door locks in my car did not work (they only lock but not unlock) and it was because of corroded terminals.

    There is at least one or two small boxes (relays?) close to the condenser buried between the radiator and the driver headlamp. See where the P/S pulley is located and draw a "line" to the front of the car
    If it ain't broke... I fix it!

  12. #12

    Dr_Snooz's Avatar
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    Re: Lost my AC idle boost

    I've gotten into the habit of dabbing a little dielectric grease on every wire connector that I open. I tell myself that I'm preventing corrosion. Seems to be working so far, but how do you prove a negative?
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


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  13. #13
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    Re: Lost my AC idle boost

    Quote Originally Posted by ecogabriel View Post
    Ditto on the solenoid and diaphragm; you snooz have the '89 manual right? (yeah, I bet you do)

    A/C idle boost was dead on my '86; solenoid was dead. Replaced solenoid with a jy unit and it now works. You may get a used one from the jy but take a multimeter with you to check continuity between the contacts; if there is continuity it most likely work.

    I have one or two solenoid spares if you do not have one and need one.

    I dunno what is good for headaches, but if yours is bad and lasts a few days I would suggest a visit to the doctor or at least get your blood pressure tested. Hope you get better
    Do you have any working A/C Idle Boost Solenoid Valves still available? I have a 1986 Honda Accord LXi, and replaced two A/C Idle Boost Valves with the screw adjustment, but they don't work, so suspect it may be the A/C Idle Boost Solenoid Valve. I'm in Arizona.

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