'99 Si A/C - ECU Question - Please Help!
Thread Starter
Junior Member
Joined: Nov 2005
Posts: 21
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From: Duncansville, Pa., USA
'99 Si A/C - ECU Question - Please Help!
I have a '99 Civic Si and all of a sudden the A/C stopped blowing cold air. I noticed that the compressor was not kicking on. I checked the charge and the freon is fine. I jumpered the high pressure switch and that's the only way I can get the compressor to work. I took it to the local Honda dealer and they told me that the ECU/ECM Computer needs replaced. My question is, does the A/C run through the computer and without throwing any codes could this diagnosis be correct? Just thought I'd ask the experts on here before I decide to buy a new computer for the car. Please respond as soon as possible. Thanks for the great site! Bill
Honda-Tech Member
Joined: Feb 2007
Posts: 542
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From: attleboro, ma
Re: '99 Si A/C - ECU Question - Please Help!
yes the ac switch runs to the ecu so that the ecu can increase the idle etc, so that the ac doesn't bog it down. i don't have a wiring diagram or pinout but im sure someone could post a link. I would check the continuity from the ac switch to the ecu first. if that check out, maybe the ecu to the relay, and from the relay to the compressor. the relay could also be bad.
Thread Starter
Junior Member
Joined: Nov 2005
Posts: 21
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From: Duncansville, Pa., USA
Re: '99 Si A/C - ECU Question - Please Help!
I checked everything back from the compressor to the ECU and all indications are the ECU, but wanted to make sure before I buy one. Thanks for the response! Bill
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Joined: May 2009
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Re: '99 Si A/C - ECU Question - Please Help!
With a/c (since im a ASE mechanic lol) you have a low pressure switch and a high pressure switch to turn the clutch on and off from the switch inside the car, if the switch isn't sending signal it wont turn on either or if ur freeon is low or pressure is to high it will kick off, id go get your a/c checked, alot of times its free or 20 bucks to get it looked at and they will tell you that you are either low on freeon or you are outa freeon and its just air in there
Thread Starter
Junior Member
Joined: Nov 2005
Posts: 21
Likes: 0
From: Duncansville, Pa., USA
Re: '99 Si A/C - ECU Question - Please Help!
As stated above, I checked everything myself (freon is ok, compressor works when jumpered, clutch kicks on and off when jumpered and switches are fine) and when the Honda dealer did a check, they said it's the ECU and I just wanted to confirm that the A/C went through the ECU. I know it didn't on the OB1 Civics. Thanks for the replies! Bill
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