On my 3rd Isuzu, a1994 Trooper with a 3.2 dohc motor, It's for my wife. We bought it with the air not working, but you could "jump" the compressior straight to the battery and the air worked fantastic! So I'm thinking it's something simple, a switch orthe like.


Long story short, the shop I use (when I'm over my head) said that the ECM is not sending the ground to the relays that run the compressior, and I need a new ECM.


So my question to those in the know, is , could there be something else (relays,fuses all checked out) thatI should check for before dropping the $$. Thanks in advance.

 

if i remember right,there is an thermostatic switch inthe evap case,that monitors evap temp,if the ecm doesnt see the correct signal it will not engage the compressor,in my carrer of working on isuzus i never replaced an ecm for an a.c problem,but i havae replaced a few ofv those switches.i would check there first.an check for fuses make sure the system does have power waiting to egeage the compressor on it own,also make sure the truck is not overheating the ecm will turn off the a.c. for this too

 

Thanks Isuzuguru. I'll put eyes on that. It's not overheating (just had t/belt,w/p and thermostat replaced,was time)Power is at the7.5 amp fuse for the a/c, it's just not coming on. The light doesn't even light up in the cabin. Electronics are not my strong suit, so when the shop said the ecm was not sending a signal to kick the relays, Ican only go by what I'm told.Thanks for the advice.BB

 

dont go by the light in the switch the bulb maybe just blown,

 

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Agreed... my light bulb was blown, but AC works great... just found a new switch with good light from a Rodeo after trying a few Trooper ones... if in a junk yard, they're easy to find, and very easy to remove/install.... take a few if you can, because it seems many are already blown out... and the bulb is VERY hard to acquire new...
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I''''m reading through this thread and I have a similar problem with a 96 trooper, The A/C compressor won''''t engage, blower won''''t blow, heat or A/C and the charge indicator light, brake warning and 4wd indicator are on, everything else works fine, any ideas? Edited by: sika_deer

 

On 3.2 v-6`s if the rubber between the ballancer and pulleys starts deteriorating the alternator doesn''''t charge properly because that rubber bonded pulley slips that spins the alternator , and if less then 12.5 volts goes to the computer the ac and blower dont work causing all kind of weird problems like ac and fans as not working. with the ac on it looks like the cooling fan is cycling on and off as the pulleys actually slips every time the compressor kicks in due to the extra drag.


Its a weird set-up as the harmonic balancer is solid and a1 piece up to the power steering pulley which is way to the front odly enough and not effected,but the alternator , ac and cooling fan are powered via that rubber insulated bonding material holding those drive pulleys in place ,and it will also cause squealing and rattling noises no matter how tight the belts areso it might be worth checking out if you find no other explanation.


The one nice thing is i had 1 completly go unable to turn the alternator ac , or fan but the water pump is driven by the timing belt so you can get home without overheating and the engine runs fine unless the battery gets fairy low.


seems like the 2 isuzus i hadwith 3.2 engines both needed new balances costing $ 178 each for the complete assembly at auto zone ,which can get it in 1-2 days and both failed at 160,000 miles and 200,000 miles respectivly.


Good time to change the timeing belt also as mine were both peeling apart and ready to snap and the pulley assembly let me know the timing belt was shot.[img]smileys/smiley14.gif[/img]





BEST LUCK TO YA....Edited by: Bull