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Re: 88 9000T AC Air Con issues - Long Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Sun, 6 Jul 2008 12:17:57
In Reply to: Re: 88 9000T AC Air Con issues - Long, Shawn C, Sat, 5 Jul 2008 17:30:46 Members do not see ads below this line. - Help Keep This Site Online - Signup |
OK, if you get 12 volts at the pressure switch, then at least the ACC is asking for AC. Good start.
Here's a really quick trick - disconnect the blue wire from the compressor. Put a voltmeter on it, and start the car. If you get 12 volts within 15-20 seconds after starting the car, then the AC relay contacts are bad - jump down to fixing the relay.
So the 12 volts start from the ACC ,goes through the pressure switch, then goes through the freeze up switch on the evaporator. If all those switches stay closed, it sends 12v to the AC relay. If you know you get 12v out of the pressure switch, it's probably easier to go straight to the relay. Checking the evaporator switch is a pain, and it probably isn't what's wrong.
It's been a long, long time since I've worked on a '88, so upon review, the relay panel doesn't drop down. You need to take out the glove box. Sorry. Taking out the glove box isn't that hard. I suggest you get a torx socket set if you don't already have one. You want torx drivers that slip onto a typical 1/4 inch drive. You're going to want a real short torx head. Step 1 in taking out the glove box - DON'T TAKE OFF THE DOOR! It'll never go back on right. Step 2 - open the door, and remove the screws at the top rim of the glove box. Then, with that short torx socket, undo the lower ones. You can't access them with a long driver, but with a short socket, yes. With the screws out, slide it out carefully; there are wires on the interior light. With the glovebox off to the side, you'll see the fuse panel, and two screws at the top. Undo those, and the relay panel drops down on hinges.
The AC relay is on the second row from the front, the second one in from the left. Pop it out, and stick a voltmeter into the socket where Pin 86 went. Start the car with the AC on. You should see the voltage on pin 86 jump up to 12 volts within 15-20 seconds after the car starts. If so, everything is working up to the relay. If you don't get 12 volts, then the evaporator switch is bad. Unlikely.
If you jumper pins 30 to 87 with a BIG fat wire and the AC compressor kicks in, then you know the compressor is OK, and you're down to the relay. If the compressor doesn't kick in, either the clutch is bad or the clutch Ground is bad.
If the relay seems bad, I recommend you try and fix it. It's got a bunch of electronics, and if those are bad, it's time for a new relay. BUt the contacts could just be dirty. Pop off the case, and check the contacts. If they look burned beyond recognition, replace it. If they're just dirty, try cleaning them up with some fine sandpaper or an emery board.
The clutch takes A LOT of power. Just a little carbon buildup on the contacts can cause a little resistance, and that causes enough voltage drop to keep the compressor from turning on. And you'll read near 0 volts at the compressor because the voltage drop is all across the relay contacts. If you remove the load of the compressor (disconnect the blue wire from the compressor and stick the voltmeter on it), then there is no current flow through the relay contacts - the meter doesn't pull much current at all. The resistance won't end up with a voltage drop.
posted by 76.200.21...
, Sat, 5 Jul 2008 14:05:59, Sun, 6 Jul 2008 12:17:57 <-- Viewing This Message
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