i have a 90 crx si, and a while back my ac was'nt working, and i paid to have this place fix it, and they told me they narrowed it down to the ECU, and said the part that controls the air conditioning in the ECU was "burnt"????, thats what they said, and since it was summer in texas and i just wanted it fixed, i just got a new ECU off ebay and sure enough AC worked after putting it in.

my question is, what does the ECU control on the AC exactly??? does anyone know, ...................cause the ECU worked with the car as far as driving and everything except the part that controls the AC, and basically i wanted to sell this ECU, but when i sell it on ebay i will have to mention that the AC won't work with this ECU, so i probably won't get much money for it, cause most people want AC !!!, so is it even worth even trying to sell this?

 

The ECU doesn't do anythign to turn the A/C on.
The only thing the ECU does when A/C is on is bump the idle up a little.

Everything else in the A/C runs on it's own. Not having it connected to the ECU won't stop the A/C from running. It may stall at stop lights, but that's it.

You mechanics were either trying to scam you into buying a new ECU or just plain didn't know what they were doing.

 

if it's a pm6, i'll take it for $10.

 

pin b2 is the ac compressor clutchrelay

 

whats the ac compressor clutch relay? maybe thats what fried on mine

honda house is a pretty good place, they are about equal to taking it to a honda dealer, and usually i don't take it there cause its like $60 an hour for diagnosis, but this was ac stuff which i was'nt familiar with.

but i don't think they were trying to get me to buy an ecu, cause i did'nt get one from them anyway and they did'nt care, they already got my money from the diagnosis part and for that at least i knew what to get. actually i will try and put that ecu back in my car when i get home just to make sure the AC still does'nt work with that ecu, if AC works then i will be confused, but at least i can sell it.

 

The ecu controls the ac compressor clutch engagement. Meaning it can "turn off" A/C under pre-determined parameters.

I believe there is a thermo sensor switch that tells the ecu if things are getting too cold (moron using AC during winter) and disengages.

Also, under WOT the ecu disengages the AC clutch for more power.

 

thanks, that cleared it up pretty good for me, thats probably what was wrong on the ecu, and i guess i will just sell it cheap on ebay to someone that does'nt have AC, or since i won't get much money on it, i should just keep it around as a spare ECU.