Hey guys. My girl has a 96 Cavalier Ls Vert with the LD9. The issues im having with this is the HVAC controls. With the car off and key out the ignition and drivers and passenger side doors opened, you can still turn on the AC button (the light turns on) and the rear defroster button (light will turn on with that also). Now with that said, she also has NO speeds from the blower motor. Now I did have a issue with the wiring bc the fan wasnt turning on at all, so I wired it to ground, and it just stays on when the car turns on, no really a big deal bc it stay at current temp (half way) at all times, so not really worried about that at all. I just wanna know has anyone come across this problem too?? If so what was is?? I know its not the resistor bc like I said nothing comes on. Im gonna check the blower motor just because, but it still dont make sense that you can turn the ac and rear defrost on with the car off. Thanks guys, any help will be great. I picked up a working HVAC head unit also, but im just worried abt replacing them bc I cant get the damn clip from the hot/cold off without breaking it (did that on my parts car, bad ju-ju) lol. But thanks guys, and I appreciate the help. I really hope its something simple.

You can get the clips at napa or carquest if you are patient and know what to ask for. Swap out the blower motor relay, check the blower fuse, and un-do your ground wire(Return to factory wiring) and see if that corrects that. The ac and rear defrost buttons may be a combination of issues all would require a new head unit as far as i can tell from the wiring diagram. Dosent sound like anything terriably mysterious is going on so good luck!


Remember... One test is worth a thousand expert opinions.

If the buttons are working, then you've got a positive feed that shouldn't be there with the car off. I'd suspect something wrong with the ignition switch feed, but you're going to have to get a proper schematic and start tracing out wires and find out what's what... instead of creating additional problems, like adding a ground that shouldn't be there.

John, Thanks man. Yeah I figured something was up with that. I did the ground to the fan so she could just drive the car (I found that issue and had to hurry and fix it bc she needed the car the next day due to her starting a new job so it just is a temp fix) which also brings me to this. On the cooling fan, the negative was getting full 12v power. I have the manual that I downloaded from here for the cars, and I followed the scematic to the relay , to the coolant temp switch, and to the junction block under the hood, to the computer. I switched some relays around, even hotwired the relays to make them work, and all checked out good. But when I checked the negative (IIRC is the blue wire going into the cooling fan) it had 12v battery power. Now im not really thinking coolant temp switch bc the temp guage works fine. But with this and the blower/hvac controls not working im wondering if its tied in somewhere. The cooling fan is what I "rigged" to the ground. But since i hotwired the relays and they checked out fine, I know neither of them are bad. I too am thinking the headunit is bad, so I may just plug the new one in, and just see if that fixes anything. If not, then I know its a wiring issue. The fan was also "rigged" after we noticed the blower system doesnt work and that we can turn those buttons on wven with the car off, so im not really sure if that has anything to do with anything. But, even with the ac switch turned on, and the controls to the max ac setting, the fan never turned on either. So, im not sure. I think Im just gonna have to stare at the schematic for a while till it sinks in. Im sure ill find it, just how long is the question lol. Thanks for the help guys, and please, keep the ideas coming, bc the more I know before I rip into this car, the better off Ill stand against it. I do appreciate the ideas!!!!

So you aren't talking about the blower motor and grounding... now we're on the cooling fan? Damn, I'm confused. Let's do it one at a time, please?

Let's start with the cooling fan... because that's a much bigger issue than the blower motor. The fan relay is controlled by the PCM... so you need to see if the output is getting to the relay or not.

There's always a ground to the fan. The only thing controlled is the +12V feed (the light blue wire). That comes from the relay in the engine fuse box. Take the relay out, then use a small wire to test it... put the wire in the slot where the #86 pin goes when the relay is installed. Then put the relay back in place (make sure the wire only contacts the #86 pin though). Then try putting the other end of your test wire to ground (or the battery negative), and see if the fan comes on. If it does, then you're missing the feed from the PCM, or the PCM is not telling the fan to turn on.

In regards to the fan not coming on with the A/C button... if you have no A/C refrigerant pressure.. the fan won't come on. Does the A/C blow cold when it's on? Or is it warm, ie the system needs recharging?

Ok, sorry to confuse the hell outta you John, lol.

Cooling fan: When I put the car back together, and ran it, I noticed the cooling fan didnt come on. Now, the ac has no freon in it at all since we pulled the motor. Now im not sure if the cooling fan worked before or not since my main concern was to get the car home bc the engine was knocking. Now, I know the relay runs off a feed from the PCM. I have yet to see if the car gets hot, will it send it. I have tested the relays with power and ground, and they all work (I hear them click). Now, I know the cooling fan should have ground, and It just runs off a 12+ BUT, when I checked the ground side of the fan, there was 12v + constant (car on or off). So, I clipped that, and put it to ground, and now the fan stays on with the car on and engine running. But come to think about it, I think it is the coolant temp sensor, bc It was broken during rebuild of her engine (the plastic plug case was broke) and for the mean time we just put the connector onto it, and even tho its reading the temp on the dash, the fan stays on as if the coolant temp sensor is unplugged, so that could be the reason with the issues of the coolant fan. Next weekend ill throw another one in since her 2.4 needs a water pump anyways. Thats not really the issue at the moment. But I hope this explains enough to let u get un-confused .

Blower Motor/HVAC: Now when i got the car running, I went inside to turn on the heater so the coolant will flow through the heater core, and thats when I noticed the blower didnt work. But after we filled it with coolant and such, we turned off the car, and just by luck I started playing with things inside the car, and just hit the buttons, and they came on. Now the AC does not work bc of no freon and as of recently needs a new compressor (old one making noise as usual). So Im not worried abt the ac right now. My main concern is getting the heating system to work. Now when ur driving the car, obviously the air comes through the vent, so I know the actual vent selector is working, just not the blower. But I forgot to mention, the AC button on comes on if the vent selector is not in the OFF position. Meaning, if its on the floor vent selection, you can activate the AC button, while the car is off and key is out of the ignition. Im thinking, like was said b4 its possibly a bad hvac unit. But im not sure since I can technically turn on the system with the car off. The rear window defroster can be turned on reguardless of where the vent selector is with the car off and key out also. Its just the fact that the blower isnt working at all.


John, I hope this makes it easier to understand. Sorry for the confusion. Its just hard to explain when ur not looking at it and your trying to type it all out. thanks again for your help.

are you saying that just the defroster light is on but nothing else is happening, right? one of my Js did the same thing but since nothing was happening with it i just ignored it. never gave me any problems at all

Tabs, No. Im saying u can activate the defrost and the ac buttons with the car off, and key out. Its not a big issue but, since the blower isnt working, it may have something to do with it. And im not sure if it actually turns the defrost on or if the button just lights up.