Hi. '95 Neon with manual transmission. Several years ago I declined to replace the original air conditioning compressor when it failed at 45,000 miles (now 58,000 miles). The local shop unhooked something electrical so the compressor wouldn't try to cycle (it was frozen). Since then it's been clear that the engine/computer doesn't realize the compressor isn't functioning. Whenever I turn the dial to "defog" the engine tends to run-on well after I take my foot off the gas as if it's boosting power to compensate for the A/C running. Nothing serious, but I can run at a steady 40mph for up to 20 seconds without my foot on the gas before it begins to idle down! The run-on is more subtle as I stop or shift, but it is noticeable then, too. This only happens when I use "defog" (of course I don't turn the dial to A/C 'cause it doesn't work)!
I commute a few miles by myself, and the weather doesn't usually force the use of "defog". So, this is not a problem for me, but my teenager will be driving this car soon. Any advice? Thanks.
EZ4U2CHere
09-30-2005, 04:13 PM
My car used to do the same thing every once in a while. Very rare, but it did do it. It had nothing to do with removing the A/C though. I think it was always just a coincidence that the A/C or defrost was on.
I cleaned my TB, IAC, and TPS and all is well.
dodgeneonACR98
10-01-2005, 04:26 AM
My car does this also ! The reason it does it in Defrost mode is becouse the A/C is kicked on while the car is in defrost mode. ( the cause may be that your a/c is low on cold juice lol ( 134r refridgerant).It don't make sence but hey.
I bet it didn't start till a good while AFTER the A/C was disabled.( after the refridgerant bled off completely). RIGHT? That was the case with mine anyhow.
Do a search at neons.org on disableing the A/C while in defrost mode. There is a part of the circuit board that you can cut ( just cut the metal band that goes bettween two pionts dont cut the circuit board). Im sure there is a detailed HOW-TO on the subject.
I am without a doubt that this would CURE the pboblem. But you may want to look at cleaning your sensors on the T/B, some say a sticky IAC will cause this problem, while I'm not ruleing that out but it hardly seems to me like the Idle Air controler has anything to do with the A/C. But again Ive been wrong before........Hope this sheds some light on it for ya.... GOOD LUCK !!!
rice_eater
10-01-2005, 12:53 PM
Mine does the same... (I think its a neon habit for the A/C to go haywire). Anywho, did you have just the A/C disconnected (like just the wiring that turns it on when you want it cold) or did you have the entire pump disabled? Because (like dodgeneonACR98 said) your A/C automatically is turned on with the defrost, so it may still be trying to cycle while on defrost. Could a vaccum leak somewhere in the defrost or A/C system cause this as well? Thats what i'm thinking the problem may be, but i'm not sure, because i can hear the pump click on and off but the vents also make a hissing sound like theres a vaccum leak somewhere. Has anyone had this problem and figured out how to fix it?
dodgeneonACR98
10-02-2005, 06:45 AM
It does act like a vac. leak doesn't it. I think it may be caused by low refridgerant in the A/C system. If youll take notice. that most people with this problem are out or really low on the refridgerant.I know that mine started after I unhooked my A/C belt and all the coolant leaked out.I took my belt off becouse I was sick and tired of throwing it off every time I hammered 3rd gear.Hope we do get this one figured out. Id like to fix mine LOL.
tchase
10-02-2005, 11:06 AM
I know exactly what you mean, when my refrigerant started leaking out my A/c would cyle constantly and cause a lot of engine surging. However once it all leaked out the problem went away. This is because once the low pressure cut-off switch activates and the computer will not try to turn the a/c on. I'm guessing whoever disabled your a/c did so by disconnecting power to your seized up compressor, hence the computer still tries to turn it on but can't. If you can somehow activate the low pressure cut-off (may be as simple as unplugging the sensor), your computer will stop trying to activate the a/c.
RadarLove
10-02-2005, 11:56 PM
It's just programming in the PCM causing the high idle. The PCM assumes that you're going to have a higher engine load with the a/c (including defrost) on, so it opens up the IAC a little further even when you are driving around normally. That way the car doesn't die when you let off the accelerator with the a/c on. The '95 model year was the worst for this, and some of the early builds had a recall on the PCM to help with the problem. You might check with your dealer to see if your car applies for this (might be completely free if it's considered an emissions related issue, even 10 years later...). If not, then the defrost bypass mod (simply drilling out a small portion of the temp controller circuit board) should work fine. If you really want to get a/c up again, used compressors don't cost all that much, think I sold mine for $20 plus shipping. Might have to replace a seal here and there, but the rest of the system should hold up fine.
Best of luck!
tchase
10-03-2005, 02:21 PM
I still think the low pressure switch is the way to go. This is what signals the system to shut down in the event of refrigerant loss (and thus avoid cooking the compressor). If the computer does not recieve the proper signal from this switch it WILL not enegize the A/C circuit regardless of HVAC control switch position, compressor won't engage, computer will not compensate for load. I know this from my own car which has no refrigerant and will not cycle regardless of switch position. The cut-off switch is of the "normally closed" type so if you simply unplug it the computer will think it has no refrigerant and disable the A/C. The switch is located on the A/C expansion valve which is the small (approx. 1.5"x1.5"x3") metal block in the A/C lines right before they go through the firewall, unplug the electrical connector from it and see what happens, I think your problem will go away.
worldlyone
10-07-2005, 10:22 PM
Thanks for all your replies. I'm sorry I was so long in replying, but I'm dealing with an illness in the family. I've pulled the low pressure cutoff switch connector as suggested by tchase. I'll be driving tomorrow morning, and I'll see what happens.
As to disabling the "a/c runs with defogger" default. That would be a last resort because whomever buys this car from me might want to repair the a/c, and I don't want to limit their options. Thanks again, Al.
worldlyone
10-10-2005, 04:42 PM
UPDATE: You may remember that I pulled the low pressure cutoff switch connector as suggested by tchase. After several days of windshield-defoggin' weather, this seems to have solved my problem. The car is not trying to turn on the a/c at any dial position (either a/c or defog) - hence the engine computer is not trying to compensate for the a/c load. Thanks for all your suggestions. Al.
dodgeneonACR98
10-11-2005, 02:03 PM
COOL BEANS,,,,,,,,,, TCHASE.........sounds like you picked a winner. Guess Ill be pullin my plug too,,,,,,,LOL. GOOD CALL. Thanks for the info YO !!!!!
tchase
10-11-2005, 02:38 PM
awesome, glad I could help. I wasn't 100% sure it would work but it's so easy it's worth trying.
worldlyone
10-11-2005, 03:54 PM
COOL BEANS,,,,,,,,,, TCHASE.........sounds like you picked a winner. Guess Ill be pullin my plug too,,,,,,,LOL. GOOD CALL. Thanks for the info YO !!!!!
Let us know if it works for you. I'll update this post if the problem rears its ugly head again (the weather is annoyingly good here in Vancouver again). Al.
rice_eater
10-11-2005, 05:35 PM
I just got my A/C charged for $20 the other day and the problem is gone (I was completely empty). So if pulling that plug turns out not to work i'd recommend charging the system.
BTW... that is not a misprint, i mean $20. fully charged the A/C. LOL what can i say I have connections.
tchase
10-11-2005, 11:29 PM
I just got my A/C charged for $20 the other day and the problem is gone (I was completely empty). So if pulling that plug turns out not to work i'd recommend charging the system.
BTW... that is not a misprint, i mean $20. fully charged the A/C. LOL what can i say I have connections.
Connections! I'd say. I'm marrying my supplier and I can't get it for that. LOL
We won't talk about those R-12 equipped jeeps in the yard though.
dodgeneonACR98
10-13-2005, 04:01 AM
Yeah! you stole that shit!!!!!!!!!! LOL you can't buy the recharge kit and do it yourself for that....good job........
