my car is obd2b from the factory, i converted to obd1 with a conversion harness and im using a chipped p06 tuned to my b20. the ac works fine when using the stock ecu but will not work with any obd1 ecu. i have tried several different ecus and none will kick the ac.

details...

when i press the ac switch on the dash the motor "acts" like it expects the ac compressor to kick on, rpms raise from ~750 to ~1500 but neither the fan or the compressor ever kicks on. when i turn off the ac with the switch on the dash the rpms drop back to normal ~750. this is while using obd1 ecu... ac works normal when obd2b ecu is connected.

NO i will not take off my ac, its HOT as F*** and im not going without it. i AM very knowledgeable in hondas and electronics BUT this one has me stumped.

i have measured voltages at the ecu using both obd1 and 2b ecus in place and turning on and off the ac.

pin 27:
ac on - ~0v
ac off - ~5v

other things ive tried...
3 different harness adapters
hard wiring(jumping) the ac compressor.... it kicks on but the fan wont.
replaced the relay in the fuse box under the hood

if anyone has any input that would be great. if someone has an alldata account and can get me the wiring harness diagrams for a 95 civic ex and a 00 crv ex that would be great. then i could compare the 2 and see whats different.

 

?????

 

there's basically 2 lines you need to adapt from an obd-1 ecu towards your obd-2b harness.

so from the OBD-1 ECU:

pin A15 - compressor clutch relay = pin A17(obd2-b); BLACK/RED
pin B5 - a/c switch from the dash console = pin A27(obd2-b); BLUE/RED

 

i've already checked both several times.

as stated above, signal from pin27 seems off. its not in the wiring itself though. and i dont see how serveral different ecus have the same problem

 

aaarg! you definitely need the crv's electrical diagram.

there's probably something in between those lines.

good luck!

 

i have it. both crv and eg civic.

the eg(obd1) wiring is SIMPLE. a few wires runs the whole system.

the crv is same as an EK, super complex and tons of check systems/relays/etc.

 

<had the same problem with his obd1 converted crv.

with those two wires connected i can get the compressor on though.. after some frustration i just ran a wire to a switch to ground the condensor fan relay. flip it on when i turn the a/c on.

that said, mine won't idle up for the a/c.

 

Some OBD1 ECUs do not have the components in the ECU for operating AC.

 

which ones do?

 

interesting... thought mine definitely came from a car with a/c.

(dx ecu added vtec and chipped)

the majority of them would have a/c except maybe the cx and few dx's.

 

Sorry guys but i have to bring this back from the dead. I can't find a better solution regarding this problem as i'm in the exact same situation.

My 2000 CRV manual is now converted to OBD1 and once i turn on the a/c, the condenser fan and radiator fan wont turn on together with it as it normally does when it uses the original obd2b ecu.

I read somewhere that a guy fixed his by wiring A12 FANC to A15 ACC and put a diode in between them. He said the diode is important coz without it, when the ect turns the fan on, the a/c compressor will also engage even if you're not using a/c.

I can try this approach but i don't have any idea of what value of diode to use. Plus i understand diodes have to be wired a specific way coz of polarity?

Is there a different way to fix this? Or could someone suggest a diode value if it's the best thing to do anyway?

Much love to you all!! Sorry for the long ramble, guys.