hi guys , i;ve benn tryin to fix my ac and here is the issue : clutch does not engage !
So far i've changed the old compressor and the receiver, vacuum the system and i tried charging but after around 25 min clutch still did not engage and presure went 70psi low / 70 psi high side. so i tought something is wrong witch compressor again ( since its used , i bought it from the forum) and i start cheking , but it engages if i jump it (give direct + from the battery). so i start testing and removed the compressor Relay try to switch them with the fan raley (as they are identical) so the relays seems to work fine, i checked for votage comin to the relay its comin. so I connected the white + comin to the relay with the red wich is going to the clutch (basically i did what the relay is suppost to do, make connuctivity between those 2 wires) and the clutch engaged. but when i put the relay , it does not engage. and the god damn relay is working cuz when do this to the fan , (its the same idea) the fan works, so the relay works .
so does anyone have any idea what is wrong with this AC ?
the other reason i was thinkig that could prevent the clutch from engaging is low refrigerant, but when i was charging it did not engage for 25 min wich i think is long enough. correct me if im wrong...
My question is , is there any way to jump that low pressure switch ?! cuz i disconnected the 2P pressure switch and connected the 2 pins together , thinking that will make the cluth engage if the reason was jusl low freon, but clutch does not engage

 

It's a 95 EX and the condenser fan runs when you push the A/C button, right? If so, the pressure switch and thermostat are fine. Therefore, unplug ECU connectors A and B, turn the key to ON(II), and use a multimeter to test for battery voltage individually at pins A15 (BLK/RED wire) and B5 (BLU/RED wire) of unplugged ECU connector A or B, respectively. If proper voltage is measured at these two pins, then you should swap your ECU with a known good one to see whether the compressor clutch now engages.

 

yes the fan works
so im about to check this onbe next

 

but is seems i can not find that ECU test harness connector behind the glove compartment .. o_O

 

The ECU test harness (see first diagram below) you are looking for is a special tool that must be purchased. But you don't need it. Just test the ECU connector terminals (marked by red dot in second diagram) directly as I described in my previous post.

 

thanks man but now i think its pointless since there is no power at all anymore,
i unplugged one connector right before the ECU terminals i't was not that so i plugged it back on and i found out that there is no more power to tha AC in general !
i mean the blower does not come on and the buttons dont function anymore and no green lights so... i guess im gonna bring it to a electrician and pay whatever he ask cuz im totaly lost now. no idea what happened

 

p.c. this one

 

ok update , i went to one place and the guy was really helpfull, it turned out that 7.5 fuse inside underneath the steering wheel was burn, so i chaged it and i im back at the fist point , with everything working besides the compressor clutch :p
same guy told me to change the fuse box ?! and thats all, actually something behind the fuse box he even gave me the number
18 38600-S01-A11 CONTROL UNIT, INTEGRATED , could that be the issue?

 

Whenever you suddenly lose power as you did, the first step is always to check for a blown fuse. I don't see how the integrated control unit would be the cause. Go back to testing the two ECU wires for battery voltage as was mentioned earlier.

 

alright here we go , i test the pins wich btw on the picstures and diagrams are A 26 pin and B 16 pin
i don't know why but my connector has only 22 for A
B is tha same 16

but i go ahead and measured anyway

for A 15 4.9 Volt and B5 almost nothing 0.15 V
here are the pics i took just in case cuz im not sure if that A 15 is the right one since my A unit has less pins then described >...

P.S. i saw that the cables going to those pins are not the same colors as the once going to the relay :

as on the diagram blu/red and blk/red

i actualli have blue going to A15 and orange to b5 as on the pic here...
so now what ?!
i have no voltage on B5 and in the manual says : repair blue/red wire between relay and ECU , well the one to the ECU is orange !

 

You have the connectors reversed. Connector A is actually on the far right of your top picture. If turn the picture 180-degrees, then connector A would be properly oriented. You should now be able to locate terminals A15 and B5 with the expected wires.

 

Ron. I assume based on your posts that you have access to the IN or have an ETM. I found compressor clutch troubleshooting on 22-12 for a 99 civic service manual. I can't figure out how to post it and there's a few pages to it but it spells everything out. If you can post it Freestyler couldn't go wrong

 

The OP has a 95 Civic. If you think it would help, I could post the equivalent troubleshooting pages from the 92-95 service manual. I haven't posted the pages in this thread because I think the OP already has the service manual.

 

all right was tough it was raning, how ever and managed to mesure, im was really stupid the first time as i thougt the pin numbers are counted on the connector cuz on the pictures are little circles, like the wholes
when u count on the ECU by itself then it maches everything i was looking at mirrow image and got me confused!
anyway i measured like 12 V on each pin , so i guess thats not the problem... i plugged everything back and went to the relay again maesured there is voltage to all 3 wires.
As for your suggestion i have no idea where to get the same ECU just to test it ...
i guess that is not an option since i have to buy one in order to test and that itself is like 100 $ so...

as for the 40mpg_dx00 suggestion i have all 1258 pages service manual for my civic and that didn't help so far still learned a lot from it though...



p.s. who is the OP ? me ?

 

You are the OP (=original poster).

Based on your test results, I think the ECU may be the problem. You could do the other tests detailed in the service manual but I believe it will still point to the ECU. Good luck.

 

ok thanks for all the help, as i said i have no idea where to get another same ECU but i'll try to do some research if i can find one...

"It's a 95 EX and the condenser fan runs when you push the A/C button, right? If so, the pressure switch and thermostat are fine"

so the only reason left is if the ECU is bad or low refrigerant.....but i think 50 psi should be enough on the low side to engage it.... i might try again , to vacuum and recarge to see if it will engage ...
thanks again , i'll keep u posted , if u where right about the ECU i'll buy u case of beer and ship it ti texas

OR this compressor is ****ed up as well

 

compressor is **** up, hi side suppose to be at 200-250 low side is 30 or 35 when the clutch engage.

70 and 70 meaning bad compressor
to engage your clutch take a piece of wire and jump the pressure switch.

if it was low on freon the clutch should still engage but on and off really quick.

 

ok the diagram originally posted, shows the relays are supplied hot, and the ECM provides the ground to the relay coil, to allow the relay to turn on what its wired to. so, if backprobing the stated pins in the connectors, while plugged intot he ecm, he shouldnt see voltage, he should see ground. if the circuit is good, then should see positive at both wires, when everything is off. anyways, the ECM doesnt supply the coil power to the relay, it supplies the relay's coil ground. so if you see positive power, thats just proving:
1 the circuit has continuity
2 at the time measured the relays are not being, or are not trying to be activated
3 that you are seeing the power travel through the relay, and end at the pin, but with no ground,[from ECM] it just sits as live power.

also, after furthur review of the diagram, i think that it was wise to jump the pressure switch, now try the thermo switch. i am not sure if its high or low temp cutout, i dont know where on the circuti its located, but, being as its in series to the pressure cutout, if this guy is foulty, and stuck as an open circuit, then the pressure switch never gets the supply voltage/ground to operate, let alone pass onto the clutch. and tot he last poster, yes 70/70 means a bad compressor, but thats whent he compressor is rotating, and he isnt getting it to rotate. he did momentarily to see if it can run and it did, but he didnt hold it long enough for pressure to develop. also in some cases, a TXV that is stuck open can cause a 70/70 scenario.
i have a feeling the other safety- the thermo switch is bad, check it out, becuase you have prooved the circuits as good, that the load side can run the fan and the compressor.

 

70 low side 70 high side means the compressor IS NOT enagaging which we all know it isnt.

it could be compressor still..but mroe then likely it will be electrical. the only way to find out is to go through the electrical portion which ron is doing a great job talking through to OP...then once we get power and ground to the compressor we can get teh clutch to enagge. if clutch is engaged and we still get 70-70.. THEN you can buy a compressor.

but yeah...if you get all 3 powers on teh condenser relay....and if you jump staright power to your clutch and it enagges, then i am with ron on this one... your ecu is not supplying the ground like it should on black/red wire A15 which would mean ECU.

what are your pressure readings when you manually jumped the compressor? we could get some better info if you could tell us the readings.

 

ok i look at mitchell wire diagrams and the only thing that is plug up to the ecm would be radiator fan relay and tempswitch that both share the same wire. The wire should be yellow/green.

 

First thanks to all of you for trying to help me out , i really appriciate it !!!

fastrc2

im really sure i need to see voltage on those pins , and i can even post a sceenshot from tha manual, but i agree that the relay needs + and - in order to switch , but obviously im gettin only voltage at all wires there....
wich convince my in the idea that the CPU is maybe not doing its job to give the -(ground)

I tested the the termo switch as well, which is located behing the glove compartment as described on the manual. Actually in my manual it is shown as 2 Pin connector, and it turns out mine is 3 Pin but anyway i made sure is the same wires and i jumped the switchs, but clutch still didn't engage... So its not that as welll...

as for waabaa's question
" what are your pressure readings when you manually jumped the compressor? "
i didn't masured as i just waned to see if clutch engage, cuz i was think it might be bad, i belive if i jumped it and make the clutch engage and charge the system it will be different pressure.... but i just dont wont to waste refrigerant , cuz i know i have electrical issue
btw i saw in a local forum someone selling same ECU so i'll give him a call tomorrow and see what happens.

thanks to all of you , as any ideas are welcome

 

freon isnt like gasoline. you dont waste freon by using it. it is a sealed system. the reason the freon gets a low charge is because in order for your vehicle to even have A/C, it needs to have rubber hoses that flex with engine movement. those rubber hoses slowly leak around .1 oz. a year.

your refrigerator uses freon too.. you never have to fill it up to to the fridge NOT having rubber hoses because it does not have to flex on anything. fridges use steel tubing.

i was just curious as to the readings while the clutch is engaged to see if there are any more problems besides that ECU. i guess we will find out once you get that ECU

 

to engage the clutch u jump the 2 pin on pressure switch.

the wire diagram up top is wrong because the ecm share power with radiator fan relay and tempswitch.

i post mitchell wire diagram on tuesday.

 

I don't think this information is relevant to this thread because you are talking about the radiator fan circuit, but the OP is having problems with the compressor clutch circuit. In addition, the OP's condenser fan runs properly.

 

alright today i called 5 different guys who were selling ECU's but unfortunatelly they were all 5 speed ecus.and i called few salvage shop to look for an ECU, and the only gut having one was not on stock i couldn't plug it to test if the clutch engage, and he was also trying to confince me if the ECU was the problem , the wasn't be able to drive at all.

anuway i know a guy who promised me to find me one by wednesday so... thumbs tight..

P.S waaBAAH by "wasting" freon i ment charging the system and then discharging, if opening for repairs needed, and then charging again from scratch... as i was thinking to put one can of the UV dye refrigerant and just watch for leaks and etc.
"freon isnt like gasoline" thank god its not