1999civiclx4dr

Hi Folks,

I just had my 2005 Honda civic lx 2 door into the shop yesterday. I had my a/c compressor replaced because the genius who owned the car before me decided to bypass the high pressure switch and burned it out. I had the high pressure switch replaced as well. The mechanic tested the system beyond the fuse and the system was evacuated recharged and blew cold air beyond the dashboard and fuses. The problem is it the fan blows hot air and doesn't engage the a/c compressor at the switch. Im hoping you can give me some specific things for him to check and or replace to get this going its hot and humid in NY now. He thought that the switch on the dashboard that lights up green might be gone or the dashboard unit, I personally don't think so that's why Im here looking for the expert advice.
Again the systems work and blows cold air when he "jumps it" beyond the switch and the fuses. So it sounds like the switch or something isn't telling the a/c unit to turn on. I anxiously await your response because I have a long commute and it stinks without a/c.

thanks so much!
Craig

El_Arsonista

i have a similar problem. i have a 2002 lx sedan and the ac stopped blowing cold air when my alt crapped out and the car lost all electrical power (gauges died, radio and fan died, etc).

so after replacing the alt and noticing the compressor would not come on, the mechanics said the pcm might have fried. according to them, the compressor is fine and so is the clutch and switches. they jumped a relay in the fuse box and the compressor comes on blowing cold air.

they said the signal leaving the dashboard has to pass thru the computer before hitting the compressor clutch switch. this isnt happening.

another weiRd thing is when u ground that relay and turn the compressor on, the idle will not self adjust and the engine will die if you give it some gas. this kind of tells me the computer isnt aware the ac is on and thus the extra load causes it to die ?

1999civiclx4dr

So do you think my PCM is gone?
I know you can buy a pcm on ebay etc, but is this something simple I can install myself to finish this off?
I also ready you need to have the pcm flashed? Is that correct?
step by step instructions would be great if this is my problem.

thank you for you time!

Craig

El_Arsonista

if you replace the pcm, the dealer needs to reprogram your keys or the immobilizer won't work and you won't be able to turn the engine over. I do not recommend buying another PCM.

That's the diagnosis I was given but I was hoping someone else might be able to provide more insight on this problem. Have you tried jumping the relay on yours to see if the compressor comes on? And if it does, does the idle not regulate?

I'm thinking of starting small and testing out that same relay I ground to see if the relay isn't bad. I would love to know how many components are involved from the fan switch to the compressor and which one of these are prone to go bad before I start buying things and replacing them.

1999civiclx4dr

The mechanic jumped the compressor and the new compressor blew cold air like a champ. The idle did seem to go down a little when he jumped it beyond the pcm module. I have just purchased one on ebay and am going to have it installed and flashed at the dealer. That wont be for a while but we will see how it goes.

El_Arsonista

yeah, keep us posted on how it goes....I think you may be able to get away without flashing it by holding the old key close to the ignition? I think i read that someone...might be worth a shot.

I tried grounding the relay again today and it was working...but engine died after giving it some gas. Also, looks like it drained the battery pretty nasty (cranked a few times over before it could turn back on).

Something tells me whatever regulates the current after the extra load comes on from the compressor isn't regulating what it's supposed to. Could this be the PCM ?

El_Arsonista

bump

did you get the pcm replaced?

1999civiclx4dr

Well Im back from vacation and I did. My screw up and waste of money I purchased the wrong pcm. I bought one for an automatic and my car is standard. They put in what I told them and the engine light kicked on and now they have to put the old one back in. I had them check the a/c with the one they put in and they said a/c it still didn't work. Now Im out $160 in labor and got nothing. Now Im sad and hot. Any ideas?

1999civiclx4dr

Plus the Honda mechanic said some of the wiring was not oem and basically refused to work on unless all brought to oem condition. Don't ever use Carbone Honda in Yorkville NY as their salesman are crooks. Usually the service was good there but this time it was not.

El_Arsonista

ufffff....sucks to hear that. I have a 2002 lx 1.7 automatic but not sure if your extra PCM will fit a 2002...I think they are interchangeable up until 2004.

like I initiallly suggested, I would start troubleshooting from small to big. I'm not familiar with troubleshooting electrical stuff (maybe someone else here can provide us some insight) but how would someone know whether something is working or not?

Im thinking a reasonble plan of action would be using a volt meter to probe switches from the dashboard all the way to the PCM to the relays in the fusebox under the hood to the high/lo pressure, thermal and clutch switches on the compressor.

The shop that diagnosed my car gave me an electrical diagram of what "things" look like from the dashboard all the way to the compressor (Which shows which connections on the PCM enable the compressor clutch, etc). I can probably scan it and upload it.

1999civiclx4dr

Yeah kinda sucks, we all work hard for our money and hate throwing it away Ill keep you posted on progress, unless summer ends first. thanks...