Ok, the main problem with the a/c is that it cuts in and out. It may blow cold air for a little, but then blow hot, back and forth.. I just let the car idle in the driveway with the a/c on and it strangely was working most of the time today, but the fans would stop briefly for a little bit then kick back on. The air got warmer when the fans turned off so the compressor probably disengaged as well. I'm not sure, but I believe I heard a click as the fans/compressor turned on/off, so I'm guessing something was triggering the relays..

I pulled out the control unit since many people say some solder points are bad, and the board appears to be perfectly fine. All solder points look good to me, so I'm guessing that isn't my problem..

Does anyone have any other good ideas as to what the problem might be? I'm considering rigging up the compressor to stay on for a little wire so that I can see if maybe the clutch is dying, but is there any danger to doing this? Would I just give the single wire going to the compressor a +12v power source?

Could it just be a bad relay? I was looking around the engine bay and the wires all appear to be intact but of course I couldn't see very much. This problem is rather irritating and annoying because it's not a clear cut problem. It's starting to warm up around here, and I'd like to not be sweating on my way to work. Any help or thoughts are very much appreciated. Thanks!

-Mike

 

Update: I resoldered the points on the heater control unit where the green harness plugs into just to be sure.. and it doesn't seem to help at all...

I also noticed that both fans do in fact turn off, and I'm pretty sure the compressor turns off as well, intermittently. This I'm guessing would certainly have something to do w/ a relay or some other piece of electronics going bad, correct? If the compressor's clutch was going bad the fans would stay on and the air would just get warmer correct? But instead, in my case, the fans kick off momentarily instead..

I also noticed last summer when I first had this problem that someitmes the actual A/C LED on the control panel would turn off, even though the button was pressed.. It doesn't do this anymore, the led stays on even when the fans cut off, any ideas? I'm not sure where to start looking for the problem. My guess would be the relays, but usually they tend to just stop working after a little while....? Any help is very much appreciated, Thanks.

-Mike

 

Could be the control unit itself. Sometimes on mine I will push one of the buttons for fan selection, and it won't do anything until I jiggle the wiring harness connector on the bottom. If your lights go on and off, that may very well be what it is.

This is apparently a common problem on 4th gens and there was a write-up on Prelude online where you just take the control unit apart and solder a couple things. Here it is--->http://www.preludeonline.com/s...66192

 

Hmm ok.. yes I do have the problem of the lights going off once in a while, I smack the dash and they come on again.. I was worried that the control unit might be the problem... I'm wondering if maybe it's a lose wire below instead...? I guess I'd need to take a look at the article..

Is there an article anywhere else besides preludeonline.com? I don't want to spend $7 just for one tutorial.. If anyone could redirect me to another article or even loan me their login/pw for a mere hour or so, like change it to a temp pw, then change it after a short period I would be more than grateful. If anyone could sum up the article or anything I'd greatly appreciate it. Thanks!

-Mike

 

Hawkze thanks for the reply.. does it say exactly what they solder? I had mine ALL apart today and soldered the pins that connected to the green garness on the board, and that didn't help (they did look fine even before re-soldering them). Unfortunately I don't have a login so I'm not sure what they try, would u mind describing what they did?

I'm wondering if there is anything else it could be? I've been doing searches all over the place and it seems like the control unit problem usually shows up w/ other buttons not working properly either.. Once in a while the lights don't light up the control unit, but it's pretty rare.. I know this means that it's getting a bad connection, so maybe it's a problem, but other than that problem, I have no problems w/ the unit not changing the vents to lower, upper, etc.. I'd rather be 100% sure of all my other possibilities before replacing a $300+ part.. Thanks.

-Mike


Modified by SlowTeg at 12:59 AM 4/19/2005

 

Here, I'll copy and paste for you...(but don't tell anyone )

FROM PRELUDEONLINE.COM\/\/\/\/

SYMPTOMS:
When your driving your car at night and hit a bump, all of a sudden there are no lights on the climate control in the center of your dash .. then they will be there and flicker and go on and off ... Or, the lights just dont work or go on / off when you hit your dash (mechanical tap).

When your changing between the vents to the upper Vents, Floor/Vents, Floor and sometimes the airflow will change and sometimes it wont. The buttoms may or may not light up to the selected airflow. If you let it sit there, it will eventually go where you want it ... sometimes not.

A/C doesn't work. The green light may/may not come on with the button being depressed. A/C will work sometimes, but other times it will blow hot air or go warm/cold and cycle between sporadic.

CAUSE:
Where the wiring harness/plugs go into the underside of the climate control, the solders on the pins that go into the plug come loose and dont make a good enough connection to the airmix unit (on the firewall behind center console).

THE FIX - IN A NUTSHELL:
In a nutshell, take out your CC, remove the casing, pull out the circuit board and re-solder the backside where the pinouts go for the plug. To define resolder: Heatup the solder on every pin until it melts and cools. Add more where needed. Let it cool and put it back .. voila!


THE FIX - DETAIL DETAIL DETAIL:
First things first, and the 2nd most pain to do of this repair:

Take off the shift boot!
Get a cloth and put it over a flat head screwdriver so you dont damage the shiney plastic covering on your shift ****. Above the shiney ring, insert the screw driver and pry down (Insert it from the back side facing the trunk of the car. When it comes down a little bit, hold it down and replant the screwdriver lower so you can pry it down furhter and further, eventually it should just pop off. The first time I did this I was able to hold ALL of my body weight on just the top of the boot and it came down.
* Other info - you can't see this when the boot is on, but there are 2 plastic tabs that the plastic part in the boot clip up onto, they are towards the front/rear of the car on the shift ****, thats why you want to pry from the back/front of the ****. You'll see what I mean when its off.

Unscrew (counter clockwise) the shift ****.


Take apart the Center Console
- Take off your stereo faceplate and remove everything from your ashtry and storage compartment (if you have one).

Put the driver & passenger seats all the way back, on either side of the Center Console there are a series of screws - take them all out. Dont mix these up and make sure the metal clips on the inside stay there, they allow you to screw this back on tight. Underneath the climate control (above the radio) are 2 more screws, take these out.. You should notice the center console is loose now .. so lift it up on the sides where its split and pull it off, put this aside somewhere that you wont kick it or scrape it on the ground. Remember, the LED for your alarm will be connected by wires, dont pull the light out or you'll need to glue it back. Dont forget to hook this up again when you put it back together.

Now your staring at your stereo, Remove the 4 screws holding in this part and remove the stereo holder. Remove the harness' behind it and antenna etc. before pulling this out. Now you should be looking at an empty dash, a bare shifter and the climate control begging to be removed.

Everything up to this point should be familiar if you've installed an aftermarket stereo and/or speaker wiring to the tweaters. Time for the goods:

Remove the Heater Control Unit

Before removing this you need to know: The vents AND climate control come out as ONE unit. You will remove the vents after.

3 screws hold this in, on the left of the CC, and on the right of the CC up underneath where the 2 screws are above the radio and on the outside, take these out. You'll notice the CC is now loose, time to have fun. Make sure all of your car parts are out of reach of you feet. I scraped the piece under my glove box on the concrete by kicking it by accident (doh!) This gets tricky.

Unplug the climate control, theres 2 plugs. One is brown (fan speed) the other is green (everything else). You'll notice 2 screws up under there also, one is for the temperature cable the other is holding in the climate control. Remove it and the climate control will slide forward *BUT* not come out yet.
I think the screw was originally gold, but I lost it and replaced it with a black one.



Now its time for the screw holding the cable, this is attached to a little bracket that screws down and has a lip on the end of it holding the cable secure. This is impotant t not to mess up and I'll explain later why. Unscrew it enough to get the cable loose, then tighten it again so you dont loose it. You need to manouver the CC unit out of its holding area where you'll see a longer piece of metal held down, there is a plastic slider that is looped on the inner cable that changes the temperature



You want to unscrew this just enough to manouver the hoop on the end of the cable off of the plastic slider (you'll be prying the plastic slider up to get the loop off) and when you do .. voila, you dash now looks like this :



Now unclip the vents (they are held in by 2 screws also) and you should have this for your CC...pull off the front buttons, carful with the clips they will break very easily! I dont know how to avoid snapping them..



and then the circuit board slides right out. There is one light bulb that is connected to a thin cable (dont have a pic, sorry) make sure you dont rip this off.. As mentioned below, this is the area of concern:



These are the loose solder connects (the ones on the reverse of the green plug). Heatup your soldering iron and touch all of these solder points, melt them ALL , the reason I say all is because I cheaped out and did most of them .. now my AC isn't always working .. but everything else, including lights does.

Put the buttons back on the front, take it to your car (just the bare circuit board) and plug it in, with the key turned all the way forward (and car not started) you should be able to change the vents and listen to hear it change now ALL THE TIME .. hurray! your done! .. If you have lights in the CC you'll notice that they are turning on also .. bonus!

Now reverse the steps and put it back together. You may need to spend some time adjusting the slider cable so that it goes all the way to cold and all the way to hot without having a gap in between, pretty straight forward just tighten the clip on the cable in the grooves that are there.

 

Thanks man, I really appreciate it! I did re-solder those exact points yesterday, but perhaps i didn't get them well enough...? Oh well I'll try it again I guess... I'll get them very well and hopefully that'll do the trick.. If not there's one other thing I think it could be searching around. Thanks again for the help! Take it easy..

-Mike

 

sounds like a problem with an expansion valve. same thing happens to my car: sometimes it blows cold air but then it'll blow ambient (warm) air then it'll go back again. I had it diagnosed by a mechanic wh o said it was the expansion valve and it breaks when the system is overfilled. They wanted like 250 for it so i said no thanks. hope this helps

 

Thanks for the help.. I am finally about done tinkering w/ the damn thing and sure enough that's definetly what it's looking like the problem is.. I was talking to a friend and apparently it's fairly common for the expansion valve to crap out in older cars.. The part isn't too expensive, but doing the work looks like it'll take more than 30min.. Thanks for the help.

-Mike

 

yea, the expansion valve is probably clogged up, change that bitch out, don't forget to vacuum the system before you put everything back together

 

Ok.. Is it pretty straightforward changing it out? I was looking at the helms manual and basically it looks like u drop the blower unit, correct? Are there any other parts that I should replace after changing it, like any orings, washers, etc? The helms manual shows a picture of where it's located in/around the blower unit but doesn't give exact instructions on changing it out. On integras/civics I believe you have to pull the dash to get to the blower, but not on preludes right? Thanks for the help.

-Mike