ECU, Wiring, Sensors
By From214to206
#311473 Hello to all of your fellow EG lovers, Ive been obsessed with EGs since my first 93 DX hatch I bought in 1998. Drove it for 500,000 miles and went on to bigger cars, then lost my job in 2009 and just a few months ago got myself a humble 92 DX Sedan, have done a ton of work all over the car, but there is one issue I havent been able to fix myself, I pray someone has gone through this situation before, because I have yet to see a definitive post on here about this, and hopefully once I figure it out, I can help others who run into it....

Ok here is all the data:


First, what I noticed right off the bat:

80A fuse in engine bay had been blown, then soldered together
Burning smell in the engine bay fuse box
Multiple wire splices from ECU to engine bay, and from ECU to AC head unit
A switch bypassing everything straight to the compressor relay
Compressor completely seized up
Evaporator totally clogged with organic matter

So here is what I replaced so far:

What has been replaced brand new:

All fuses in-dash and in engine bay
Compressor
Compressor clutch relay
Evaporator
Condenser fan
Condenser fan relay
80A engine bay fuse
Expansion valve
AC head unit (junkyard, all solder looks good, no cracks/corrosion, continuity looks good on all points, switch on and off)

Idle issue replacement brand new:
IACV
TPS
PCV
Upstream oxygen sensor
Cat

What has not been replaced yet:
AC Thermo switch
Condensor (have it, just didnt want to decompress system again just for this until I figure out the compressor issue)

Ok, so after all that work, the bypass switch AND the head unit would engage the compressor and air blew cold.

Most of this work would be completed around midnight or 1AM, I live in North Texas, so its probably 80-90 degrees at midnight.

I'd take it for a spin at night, and it was all good, compressor would stay on. When I would get off the gas and out of gear, the idle would drop so low that it would sometimes stall out (hence why I started replacing the sensors and what not, I also cleaned out FITV and throttle body really well, FITV was like 5 turns out when I went in there, now its tightened all the way down, didnt really notice any difference in the stalling, but the general timing and performance of the motor felt better after all this)

The next day on my way to work, compressor would not come on, so then Id go in and replace something else (sensors etc) and then Id get the compressor to click on, it would blow cold, then the clutch would disengage, then 5 seconds later, reengage, then 5 seconds later disengage, and repeat this process until I turned the compressor off.

Then it would not come on at all.

I have tested continuity on pretty much every wire in the entire car, in the bay, in the cabin, in the dash etc. The only thing I've noticed that is odd is the thick ground wire coming out of the back of the head unit will get VERY hot to the touch after about 30 seconds after I hit the compressor switch on the head unit. When I noticed this, the compressor had gotten to the point where it wont even turn on at all anymore, no matter what I did.

I'm getting close to taking it to the Honda dealership to troubleshoot the electrical issue, but before I did, was wondering if anyone had any ideas...

I have a copy of the service manual, but I have issues understanding some of the steps, here is an example of my lack of electrical knowledge:

"Disconnect the AC thermostat 2P connector" (I did this)
"Connect 1 and 2 terminals using a jumper wire" (I did this with a paperclip, would this work? If not, what is a jumper wire?)
"Start the engine" (I did this)
"Does the compressor engage?" (It didnt)
"Turn off ignition"
"Reconnect the AC thermostat 2P connector"
"Disconnect the compressor clutch relay 4P connector"
(Here is where I get lost)
"Measure voltage between the WHT wire terminal and the body ground" (So I put my positive probe on WHT wire terminal, and my negative probe on any ground?)
"Is there battery voltage?" (so does this mean I should see 12+ volts? What setting on meter should it be on to test this part?)
"If no, then Repair open in the WHT wire between the under-hood fuse/relay box and the compressor clutch relay" (again, lost, so what do I do, cut the wire near both ends and replace with the same gauge wire inbetween?)

Of course this process is just repeated a bunch of times, I just need the elementary understanding to complete the steps.

Any help with this would be great, and Id be in debt to anyone who knows what Im dealing with.

Thanks to anyone who has any experience with this specific issue I've described.

I love EG Civics, and definitely EG-Civic, this community rocks! I hope to be a contributing factor on this site at some point, maybe starting with this post because I've camped this website for months, and I've been working on this one issue for over 2 weeks, with 80+ hours of my own time messing with it after replacing all these components, Im really close to turning it over to a professional, but maybe Ill get lucky :)

Thanks again for such a great site, have a great day!

Jon
By From214to206
#311567 Update:

Cleaned:

ECU terminals and plugs hooking up to them with electrical cleaner.

Replaced:

Dist Cap
Rotor
Plugs
Wires

Next on my list:
Replace all the body grounds in the engine bay
Battery hookups

If this doesnt do it, Ill be almost to end of my rope outside of starting to replace all the wiring harnesses from the ECU out and maybe the ECU itself.... But before I spend that kind of dough, Ill be taking it to the dealership for a diag.

Anyone know how common it is to need to replace the ECU for something like this?

Thanks,
Jon
By From214to206
#312057 Update:

I started my ground work, on all of the connections I replaced the bolts, the ends and the wires... also took a dremel and took off the paint and primer down to the steel, and added washers.

Done:
Put a 2 gauge from negative on battery to passenger shock tower.
Put a 4 gauge from transmission to body to the left of transmission.
Put an 8 gauge from distributor to passenger shock tower.
Put an 8 gauge from A/C compressor to body right by driver headlight.
Put an 8 gauge from intake manifold to body right by driver headlight.
Put an 8 gauge from valve cover to body right by driver headlight.

Going to do:
Put an 8 gauge from thermostat to passenger shock tower.
Put an 8 gauge from block to ground (my motor doesnt have this at all, where is the best spot to hook up to block?)
Put an 8 gauge from head to ground (my motor doesnt have this at all, where is the best spot to hook up to head?)
Replace positive from the battery to the starter with 4 gauge.


I read on some post to do all of these... The post mentions that there are multiple grounds behind the passenger headlight, but on my rig there is only 1... What all should there be?

I few notes to mention, after replacing/adding these grounds, I started blowing the fuse that lights up my speedo/temp/fuel, but not the flashers...

So clearly there is a short there.... The more I look at the cabin wiring harness and the engine harness, the more I find shrink wrap and jacked up wiring down there.... Is it smarter to buy new harnesses, or rip them out and re-wire them properly without all this ghetto engineering that Im seeing?

Thanks for any responses... Holding off on taking it to somebody because I think I might be onto the fix...

Jon
By From214to206
#313275 What up fellas, update for you.

So the answer to the pressure readings was that it was completely empty.... LOL... Ok, so I take it to a local honda shop run by a mom and pop after I put in my brand new evaporator and suction/discharge hoses.

They found that the brand new retro schrader valves from O'reillys were leaking, yay.

So they put on some new ones that were worth a *%&$, put the vacuum pump on it all night and he said that there was -30 on it in the morning, which held all night (w00t!)

He mentioned the Heater Control head unit should be replaced because he mentioned my 20 year old junkyard one would sometimes turn off (probably the on and off I was experiencing) and that he took a hammer to it a few times to get it to turn on.

So we filled it up, its been like 3 days of 100+ degree days and its keeping me from sweating.

Now I have a new set of symptoms:

1. the harness and wires connecting to the head unit still gets ridiculously hot when compressor is on

2. when I first start up the motor, it blows the coldest, it seems if Im in 5th gear on the highway going like 75 miles an hour, the air gets hotter to the point that I start sweating a little when its like 100 degrees outside the car.

3. There is definitely something up with the flaps that direct the air flow, when I have it on front and bottom, it seems to operate perfectly, but if its just on the front setting, the coldest air is escaping out at my feet somehow, I plan on dropped the dash on the first day its not like 99 degrees at midnight to see whats up with that.

SO, that being said, first, is there a way that I can get my blower motor to be able to blow at like category 5 hurricane speeds instead of just like a 2" desk fan, or is there something that I can wrap everything with to prevent the 150 degree interior of the car effecting the air temp?

Im finally on the right track, has probably cost me close to $2000 just in AC alone at this point, but damn near everything on it is brand new now, so hopefully last me another 20 years.

Thanks for all the help!
Jon