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98 neon with 3+ amp battery drain: AC Clutch??

10-23-2010, 12:09 AM
My 98 DOHC neon started having a dead battery in the morning a few weeks ago. I have a 60 month Die Hard with 36 months on it. I charged it up, but it keeps discharging overnight on random nights. Last week, I took the car to sears, and they tested the battery. They believe it is OK, but I have had a die hard that went bad "intermittently".

At first, I blamed it on my wife. The key cylinder is broken, so that I can pull the key out in any position (it has been like this for over a year). I always leave the radio on, but my wife was trained to turn everything off, before turning off the ignition. I have caught myself once in a while turning the key too far, to the accessories position, and pulling out the key. Since I always leave the radio on, I know about it before I leave the car. The dead battery also correlated with mornings where my wife was the last to drive the car.

I have been driving the car exclusively for the past week, and now the battery is dead in the morning sometimes when I drove it the previous day. It is October in Philadelphia, and some nights go down in the 40's. I began to think that cold might be triggering the battery.

One morning this week, While getting a jump, I heard a loud clack that sounds like a relay. There goes the blame it on my wife solution.

Well I needed a jump to leave work today. I decided a test was in order. The plan was to put my 8 amp charger on the battery for 5 hours, then disconnect the battery at 11PM. I was then going to leave the battery disconnected overnight. If the battery would not start the car in the morning, I would know it was the battery, not a current drain. We are supposed to get our first frost tonight, so this would test my "cold morning" theory.

Well I just came inside after disconnecting the battery, and I hear a loud clank that sounds like a solenoid or a big relay. I see sparks if I touch the battery cable to the post. The clank is coming from near the belts and pulleys. I figured out how to get the 20 Amp range on my multimeter to work, and I measured the current. 3-4 Amps!! I think it might be the AC clutch engaging. It is hard to isolate exactly where the noise is coming from in the dark.

I found a post in this forum from several years ago. The author indicated they he had a battery drain that went away when he pulled the "AC fuse". That guy had other bigger issues, so I don't know the resolution of that battery drain (maybe he just left the fuse out?).

Anyway, I would like to know what I should check out. I find it strange that the AC clutch could get energized with the key solidly in the off position. I really need to fix this, as disconnecting the AC fuse means the defrost won't work right. Also, could there be some other part that could be responsible for the clank and/or drain?

Also, advice on getting the key cylinder fixed, so I can keep the same key would be appreciated. I saw a couple of posts in here indicating that it was possible. Would be easier than untraining my wife from turning the radio off every time she turns off the car.

10-23-2010, 12:17 AM
I got a good video for you, see http://www.youtube.com/watch?v=B__DqK90IIc

Check owners manual for Battery fuse's 1st, they supply the bat for Control modules when the ignition switch is off.

10-23-2010, 10:37 AM
That is a good video on how determine if you have a battery drain, by measuring the current. Most Digital Multimeters (like the one he used in the video) have a 10 or 20 amp range that can measure the current without using an external resistor.

The problem with using the AMP scale on your DMM is that you run the risk of blowing the fuse in the meter (mine is blown), or worse, on the 10 amp range (unfused) you can blow the whole meter. The 1 ohm resister makes measuring the current draw foolproof. I think I will make one of those test jigs with the resistor for my toolbox.

Anyway, I have determined that I do have a 3+ Amp drain by using DC AMP scale on my multimeter. It was dark and cold last night, so I put off to the next step for today, pulling fuses.

I strongly suspect the AC clutch is the problem. With daylight, I can confirm this by pulling fuses.

What I was hoping for is an answer to why the AC clutch would be getting power, with the ignition switch in the off position.

10-23-2010, 11:21 AM
Key lock cylinder can be replaced and re-keyed so you can use your current key, I have done this on both my Neon and Caravan and the R and R of the key lock cylinder s easy.

10-23-2010, 04:20 PM

With some decent daylight this morning, I went out to investigate. I touched the disconnected negative battery cable, and the clunk was clear as day. I put the cable on the post loosely for the moment.

I then noticed that the fuse box is conveniently right next to the battery, and the cover was easy to remove. I opened it up, and all the fuses were well labeled, along with about 5 identical plug in relays. I pulled out the 20 amp fuse labeled "A/C and ABS" and I heard the clunk again. I get the clunk by removing and re-inserting the fuse. OK the problem is in the AC circuit.

I then looked at the relays. One is labeled "AC Clutch". With the battery cable connected, and the 20 amp fuse inserted, I wiggled loose the Relay for the AC clutch. Bingo, pulling and re-inserting the relay made the clunk.
Either the relay was stuck in the on position, or a wiring problem was causing the relay to always be on. I could have proved that it was the relay if I swapped the AC relay with another relay (all of them had identical part numbers).

I needed to run an errand, so I stopped off at my local Advance Auto Parts store on the way back. I showed the relay to the guy at the parts counter, and he says "oh that is a standard Bosch relay used in lots of cars. My Volkswagen even has a few of them." He looked it up and for about $12, I got a relay with the same part number, but with a Ford logo on it.

I took the new relay home and plugged it in, NO CLUNK! I alternated plugging in the old relay, and the new relay a bunch of times, just to make sure. The old relay was definitely bad, and it was causing the battery drain.:smile: I tightened up the battery cable to the post, problem solved.

10-23-2010, 05:25 PM
I would of considered some extra fuse's, relays, and bulbs from LKQ!

Good job , this is what AF is all about!

Relays canbe fixed by drilling a small hole into the relay, and use crc electric cleaner, plug hole with a silcone sealent when complete.

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