psychotropic28

recently purchased this car with blown motor, did direct plug an play motor swap 1.7L non vtec, and now to get ac going. previous owner tried to reinvent the wheel an did a bunch of chopping and rewiring bypassing everything never fixing original problem. i have soldered all the stock wiring back to oem and started in.
first i ripped the whole mechanical sytem out replacing expansion valve and dryer, flushing evap and condensor. new orings and back together. vacuumed down the system for half an hour and filled with 23- 25 ounces of freon. i direct wired the comp to aid in filling so mechanically shes ready to go. now the original prob. i replaced the heater control and the other control with the three buttons, checked all fuses in the car and underhood all good. replaced both radiator and condensor fan. replaced the two relays in the underhood box and still nothing. here are current symptoms...
1 blower motor works fine on all three speeds
2 recirculate or fresh air valve/motor works (visual inspection)
3 selector for floor or dash or defrost works fine
4 comp clutch works fine if i put direct power to it.
5 blue wire on heater control between pink and green wire gives 12v
6 condensor fan wont turn on
7 radiator fan is cycling with radiator temp, not staying on with a.c. on
8 green light on dash for a.c. doesnt come on, kinda like the button isnt even hooked up it does nothing but the other two work.
9 car doesnt adjust idle if i hit button, stays the same
10 the ac/heater controls dont light up with the parking lights at night either. they stay dark.
and thats as far as ive gotten. tonight i was gonna test the underhood fuse box by crossing the leads for the condensor fan an make sure the fuse box didnt burnout. i have anotherone already. all the control parts were taken off a previously owned car that was dealer maintained for 10yrs so i personally know that they all worked before i wrecked the car. fell asleep at the wheel. i miss that car. thats also were the motor came from. 02 lx 5 speed sedan.

psychotropic28

ok did a test on underhood fuse box
here is what I got:
1. Test on Condenser Fan Relay:
- terminal 2/1 turns condenser fan ON; terminal 2 tests 12v
- terminal 3/1 turns radiator fan ON; terminal 3 tests 12v
2. Test on Compressor Clutch Relay:
- terminal 2/1 turns compressor clutch ON; terminal 2 tests 12v
- terminal 3/1, no visible activity terminal 3 tests 0v

psychotropic28

switched out underhood fuse box with known working fuse box. no change. terminal 3 on compressor clutch relay still reading zero volts

ezone

When you turn the AC on, do the radiator fans come on?

psychotropic28

****. did that test backwards. i need sleep. was testing pin 4 not 3 so underhood relay/fuse box is fine. tested ecu b6 and e16. had 12v power at both. moving on to mcu/underdash fuse box. tomorrow... im tired as hell.

psychotropic28

no. the fans donot both come on with the ac. but the a.c. also does not come on. at all. its as if that part of the system doesnt exist.

ezone

I'm guessing the control panel is bad.



Go to the pressure switch on the drier bottle.
Start the engine
Ground the blue/white wire.
Does the AC (and fans) kick on?

Does the other wire (blue) measure as a ground?


reconnect pressure switch wires.
Remove the center dash panel.
Locate the blue wire in connector A4
Start the engine
Ground that wire. Does the AC kick on?

oqjoi

I had a 2000 lx sedan and the previous owner destroyed! He swapped in a vtec but not the ecu. Never sealed the thing so it leaked oil like a sieve so bad that i put oil in it took it on the highway and before i even got 70 miles out, it threw a rod. Then stupid me took it to a mechanic a friend recommended.... my ac/radiator fan was hard wired to the ignition. About a month after i get it back, it breaks down. And continued breaking down once every 2-3 weeks wih these outlandish problems. I loved and hated that car. It taught me all about hondas but i spent more time under it than driving it. I rebuilt the ac system because one summer it exploded. But i never figured out how to undo the hardwired bandaid the "mechanic" did.

psychotropic28

ill try it and tell you what i come up with.
i did replace the control panel with a known (its from my wrecked car) good one. and if i ground the wire at the pressure sensor everything does come on (except that damn green light) but your bypassing everything when you do that. i did not test the other wire to see if its ground though. im guessing you want me to rule out a bad pressure switch. which is the only thing i didnt replace on the mechanical side. ill let you know what i find. which connecter is A4 by the way..

ezone

I was more interested in finding out if the AC request signal is going where it needs to be.

HVAC controller--> pressure switch --> multiplex system --> PCM ,
then PCM operates fans and clutch if it believes it is ok to do so.



Connector A is on the HVAC controller on the center dash panel. 14 pin connector. The other (B) is a 22 pin connector.

ezone

Does the car have any other odd electrical problems going on? If so, it might be MICU related.

psychotropic28

ok if by a4 you mean the top connecter on the heater control unit 4th wire down than yes it tests out a ground.
yes i tested the 2 pin connector on the pressure switch. one is hot that when grounded starts the whole system and the other is nothing. it tests as open. question... where does the other side of that wire goto so i can test the wire itself. keep in mind that ALL the wires above the radiator where hacked in two when i first started. i then soldered all of them back together. doesnt mean i didnt make a mistake or had a break i didnt see though. id like to test the wire itself if you think that could be a possibility.

ezone

Blue wire.
I don't have a car in front of me to verify your description, just a diagram here.

Not good

From terminal A4.






I didn't realize this wiring had been damaged.

If you have ground showing on A4 but it's missing at the pressure switch, that wiring mess is a good place to start. Or bypass everything and wire direct from panel to switch (as a test, of course).

psychotropic28

ok, as an experiment i followed the blue wire from the pressure switch up a little an exposed a little bit of wire to see if i grounded it that the system would come on an yes it did so the pressure switch is fine and i have sufficent freon in the system( thank god for that) so now to the why is there no ground coming from that wire in the first place problem.
ill try the direct route from a4 to switch and verify

psychotropic28

maybe im testing the wrong wire or you lost me my friend. but there are two wires that goto the pressure switch. one is hot that when grounded turns on the system. that wire goes to a4
the other wire on the switch is the ground wire used to start the system when the pressure switch senses all is good.
both wires are/should be coming from a switch due to if you just attach ground to the wire that is supposed to be ground the sytem stays on even if you turn the selector on the heater control off. to be sure i connected a ground to the blue on what i think is a4 and the sytem came on however if i used a jumper from my wire by the switch and run it in the car and touch it to a4 nothing happened
so where does the ground wire side of the pressure switch go. or do they both goto a4 and im just testing the wrong wire.

psychotropic28

it goes to the mcu. again my wayward road has led me to the mcu. just to make sure it wasnt my solder job i tested the wires for continuity on both sides of the wire mess. tests came up clean. my rewire is not faulty. solder beats those wire crimps people use so much anyday.

psychotropic28

i have a feeling some knucklehead was hooking up a radio or some other crap and shorted the mcu back when this all began with previous owner.

ezone

Easy to do LOL.

You may need to see a real wiring diagram for this.

Yes

You are missing wire colors here. Colors are the only thing to go by.

It's not a true hot, what you are measuring is a bias voltage applied to the circuit.

Blue wire at the pressure switch comes from A4 on the HVAC panel


Neither are grounds.

When you supply ground to the blu/wht wire, the system should run.

The pressure switch is wired in the middle of the request circuit between the HVAC and the MICU.

The request signal is made at the HVAC unit by applying ground to the blue wire (A4) when you push the AC button.

If the system has 30+PSI in it, the contacts of the pressure switch are closed and that request can be passed to the MICU. (But if the switch is open, the request signal stops there.)

The MICU then sends the "AC request" over a data communication bus to the PCM.


Yay.
Boo. What did you do here?

Did you have the pressure switch connector unplugged when you connected blue wire to A4? If unplugged, connect A4 to blue/white.

Switch was supposed to be plugged in when you did it. I forget not everyone knows to backprobe on this stuff. My bad.

ezone

Missed other posts while writing. It's not the micu, yours is working ok for this.

psychotropic28

ok i may have stumbled a sec. reading your last post shows me you know exactly what your talking about. sorry im a knucklehead that does most things on my own. i really appreciate you takin time to help me so lets reiterate a sec.
the blue wire goes to A4, this wire is fine it tests the same in the car as it does under the hood. the pressure switch is fine, results found from previous experiment. the blue w/white strip by looking at the hanes manual goes to either the overload protection circuit if i have one but i only have one wire coming off the compressor so i assume it goes directly back to the mcu (multi control unit/fuse box under dash)
that being said if i bypass the pressure switch by grounding the blue wire at a4 or grounding the blue wire at the pressure switch the sytem comes on. however if i jump the wire at the pressure switch from blue to blue w/white strip nothing happens.
so what next.

ezone

That's for 02-05 cars.

Yours does have the thermal protector and it's wired in series with the clutch right on top of the compressor, and your compressor has a single wire connector..
Correct, and because you were able to operate the AC by supplying a ground to the blue/white wire at the pressure switch connector that means the MICU is OK.


Reconnect the pressure switch again as stock. Put the whole engine compartment back together as stock LOL.

Go to HVAC panel. Ground the blue wire in cavity A4. Does the AC kick on?


(Did you already do this? I have a reading comprehension problem! )

psychotropic28

yes, now what

psychotropic28

ok so followed the blue w/white stripe back to the mcu. i believe its socket F9 if it reads top to bottom left to right with numbers. put a ground to it at the mcu and the system comes on so the blu w/white stripe wire from the pressure switch to the mcu is fine.
now it goes thru the mcu and comes out a yellow wire to the ecm is that correct? so what test to do now?

psychotropic28

aight so just a side note. i was thinking of doing a test on the mcu just for giggles. in that test you have to use the dome light because it'll blink signaling test mode one or two. but i my light has never worked so i was gonna replace the bulb but its not burnt out. so i used a jumper wire and grounded the bulb an viola it came on.. so theres no ground going to the dome light? lets see here....
no ground to the dome light
no interior lights on the hvac unit when you turn the parking lights on
does the dome light go to the f******* mcu too. lets find out shall we.. brb

psychotropic28

so its not ground that goes to inter lght from mcu its power. aaaand there is none. im just gonna get one and rule that thing out, sucks it $100. sigh

ezone

Sorry I had to run off, had things to do. Then took the GF and her 3y.o. granddaughter to dinner.




Stop everything!
You operated the system by grounding terminal A4 at the HVAC control unit connector.
The HVAC control unit is not grounding terminal A4. Why?

psychotropic28

you still think the hvac is bad eh... well i know it worked 100% when i took it off the previous car though but i'll order a new one anyways. i did order a new mcu just for the hell of it. so ill let you know the result when that comes in. in the meantime ill order the hvac as well i guess. hope its not to expensive. this car is turning into a mini money pit at the moment.

ezone

Ok, the problem still has to be in the HVAC controls no matter what (because you can operate the AC from the HVAC c.u. connector).
It cannot be the MICU.

Does the AC button light up when you select defrost?
Could the pushbutton AC switch be bad, or a wiring problem between the switches and controller?

psychotropic28

got the new mcu in last night, gonna put it in tonight. that vertical selector switch (hvac) is $200 brand new. ouch. (the mcu is showing other problems like the interior light so theres more than one reason for replacement)
no the green light in the center button or ac button doesn't light up for anything. and yes i replaced it with a known good one. the other two buttons work fine. recirc an defrost rear. the previous owner actually thinking that horizontal 3 button control was bad actually ripped the center button out and put a bypass switch overtop of it. nothin like reinventing the wheel.
and last but not least theres still the issue of: why doesnt the the interior lights that come on with the parking lights not work in the center console? a clue perhaps of something else?

psychotropic28

My friend EZONE, let me just say thankyou very much for not giving up on me. between you and the hanes manual i have learned a boatload so let me share some helpful tip with you.
put in the new mcu and as you already guessed there was no change. at that moment all i could think was the jokes on me but remember i was adamant about my parts being good parts. well in the beginning i said the previous owner was reinventing the wheel. to all you honda owners out there if you take things apart please plug everything back in before thinking youve blown something up.
hears a secret about the green light. if the evap temp sensor conveniently plugged in behind the radio isnt plugged back in or the sensor goes bad, everything will work and test out fine except the green light and the signal coming from the heater control panel.
yes mine was unplugged. plugged it back in( which is a real bitch to do) and vwa-la we are back in business 100%.