a/c will not turn off

[silkysmoothyjud]

1994 q45, I did a search.... I have to pull the fuse or relay to get it to stop: a/c system will run without the blower motor on. I just replaced the belt and pulley. I was running w/o for a while. Hooked it back up and shazam, ghetto rig in full effect. Any suggestions would be greatly appreciated.

[Infinitiguy19]

Have you tried the self diagnostic to see if its an electrical problem?

Look in the FSM for the procedure.

[silkysmoothyjud]

I do not have a copy of the FSM and I did a search on it and that sounds like fun, but I did multimeter the relay connectors of the a/c and fan to discover that 2 AND 5 are getting 12v, whereas only one connector is getting 12v on the cruise control relay connector. Any significance?
Modified by silkysmoothyjud at 9:59 AM 8/8/2009

[Q451990]

It's certainly not an issue I've heard of before. Most complaints are in the "it won't come on" department!

Download your FSM in our library at http://www.nicoclub.com/FSM/Q45/1994_Q45/

It certainly sounds like a wiring or even ECU (VERY UNLIKLY) problem. When you study the FSM, you will find that there are several sensors that must read correctly before the ECU will send the "on" signal to the compressor. Working from memory, so it's probably not all-inclusive:

1) Dual pressure switch on the receiver/dryer must have a pressure reading that's not too low or too high.

2) The overheat sensor on the compressor can not be tripped.

3) The evaporator sensor can not be too cold (detecting a frozen evaporator coil)

4) The ECU must not be detecting RPM's over a certain level. It will turn the compressor off at something like 5K I think. I don't know if this is to protect the compressor or to give more power to the driver...

So... if it's on all the time - I would think it's something either in the ECU (very unlikely) or something in the wiring. You might also make sure that the relay is working properly. It's possible that it's frozen in the "on" position. If you can find another relay under the hood that's like it (confirm this by more than it's color) you can swap them out for a quick test. Or just test it with your multimeter.

Good luck!

Heath

[goody90q45]

It's certainly not an issue I've heard of before. Most complaints are in the "it won't come on" department!.......

The fan control amplifier (FCA) failed in one of my Q's and the fan would only run on high speed (but would turn off). It just failed in my 94Q and the fan would not turn on at all. I know you suggested checking relays but could a failed FCA cause the fan to not shut off?

To the OP- Does the fan speed change with the manual setting or is it only running on high speed?

[silkysmoothyjud]

It is my first summer with my NICO ECU, it would be the next easy thing to check. I have already switched the relays around, same results. Its hot as hell today, I dont want to mess with it and break it right now. I have just been pulling the fuse when I want it off. I jumpered the relay to try kick the compressor back to life before I noticed the belt had broke.

Is there another relay besides the one under the hood?

The fan can be controlled manually. I pulled my climate control, everything seems normal, cept when I turn the car on, the entire ac system comes on with it regardless of whether or not the climate control is on or off.
Modified by silkysmoothyjud at 4:11 PM 8/9/2009

[maxnix]

when I turn the car on, the entire ac system comes on with it regardless of whether or not the climate control is on or off.

Meaning the compressoer engages?

[silkysmoothyjud]

Yes, compressor, fan and the whole bit. It freaked me out at first, since the NICO ECU in my car does not control that aux fan; and the last time that fan came on w/o the a/c my water pump was failing and was spewing coolant out of that hole all over the place! I pulled over to see what was up when I saw the compressor clutch move. I usually drive with my air circulation on in the cabin only: I let the air circulate and it was straight freezing cold air with no fan behind it. If this would have happened in the winter, would the compressor have kicked on? If so, would it have toasted my compressor? If the answer is yes to either one of those questions, I am pulling my a/c fuse EVERY WINTER!!!! That goes for all my cars.....

Please be advised that I refuse to work on my car over the week as it agitates me enough to affect my performance at my job. I will go out and f it up this weekend. My job is about two miles from my house. I do inside sales and sit around on the phone all day. So Niqole just sits at my job and in my garage, getting fat. I put about 10 miles a week on her now....
Modified by silkysmoothyjud at 7:20 PM 8/10/2009

[Q451990]

Please be advised that I refuse to work on my car over the week as it agitates me enough to affect my performance at my job. I will go out and f it up this weekend.

Not sure why that was so funny to me, but I like that quote. I'm leaning toward a bad relay. You should be able to check it easily enough by checking for the signal from the ECU at the relay.

Good luck... let us know how it goes this weekend. By the way helps a lot when you're dealing with one of these electrical issues. It works a lot like BG quick clean or marvel mystery oil. Use just the right amount and it helps, but if you overdo it you run the risk of really messing something up!

Heath

[silkysmoothyjud]

What pins on the fan and a/c relays are getting 12v with the ignition off/on on your system? I will confirm 12v on the pins then pull my ecu this weekend. After that, I will have to (gulp) do the diagnostic check.....

I don't mess with MMO, too many bad threads. But I did the quick clean and I blame it for jacking up my MAF, but all I had to do was follow the procedure for cleaning it and it fixed the issue.

I also use that MOA, highly suggest it!!!
Modified by silkysmoothyjud at 8:49 PM 8/11/2009

[Q451990]

I would try the easy stuff first, like the self diagnostic and checking the relays.

As far as voltage readings at my relays, I think you should use the information in the FSM. There are enough differences between the '90 and '94 that there may be a difference in what is normal for your car and mine.

Heath

[silkysmoothyjud]

Call Heath now for your free reading, ding ding ding we have a winner, it was my ecu, replaced with OEM, and emailed Wes. I tried the NICO ECU one more time to see if it has to reset or something but with no avail. Now I'm gonna get owned by pos 300s and mustangs until I get my NICO ECU back

I am gonna disable the a/c systems (pull the fuse) on all my cars over the winter from here on out......

[elwesso]

did the AC ever work properly with the NICO ECU installed? Something sounds fishy, because typically on ECU's things like part of the ECU doesnt "fail"

Usually either they work 100% or 0%....

BTW, got your email but Im not 100% sure how im going to handle it, a few logistics things on my end but I will get you taken care of!! I think it will be a month or so before I can get you another one though, I just sold my last one a couple days ago..

[Q451990]

I am gonna disable the a/c systems (pull the fuse) on all my cars over the winter from here on out......

Don't forget that the A/C plays a major role in defrosting your windows in the winter. We have high humidity here, so It may not be as much of an issue in your area. It's also recommended that you run the A/C from time to time in the winter just to keep the refrigerant flowing and everything lubricated. I leave mine set to "Auto" all the time. With this style of failure being so rare, I don't know that I would go to the effort to disable it, but of course it's your call.

Anyhow, I'm glad to hear that you got it figured out. This is the first time I have ever heard of this issue... Probably the second ECU failure I have ever heard of - with the other one being water damaged due to a leak in that area after a wreck that wasn't repaired properly.

Heath

[silkysmoothyjud]

Yes, the a/c functions normally with oem ecu. I understand your suspicion and I would be more than happy to send a "you tube" video of each ecu if you would like. I am sure you will get the same result if you test it as well. I usually do not use my a/c, it sucks down the gas and takes away too much power, but it got so hot in MO I started to use it on my short trips to work, then the short came out of nowhere. Please let me know how you want to do this, or please send me your addy via email. I am missing it already!!

I would be interested in knowing exactly went wrong on the inside....

[elwesso]

Yes, the a/c functions normally with oem ecu. I understand your suspicion and I would be more than happy to send a "you tube" video of each ecu if you would like. I am sure you will get the same result if you test it as well. I usually do not use my a/c, it sucks down the gas and takes away too much power, but it got so hot in MO I started to use it on my short trips to work, then the short came out of nowhere. Please let me know how you want to do this, or please send me your addy via email. I am missing it already!!

I would be interested in knowing exactly went wrong on the inside....

my question is did the AC ever function properly with the NICO ECU installed?

[silkysmoothyjud]

OOOOPS!! Quick answer on my lunch break. I got my NICO ECU in October or November last year. It was not doing this when I first got it, I don't recall ever using the a/c. Niqole's a/c belt tension wheel failed, the a/c belt broke and I was going without an a/c option for a minute. Once it started getting hot again I got my new tension wheel and my belt installed: the a/c has been stuck on ever since. I started noticing poor fuel economy, lack of power and then I heard the aux fan come on (I always recycle the cabin air). I confirmed that it was the ECU last Sunday.
Modified by silkysmoothyjud at 7:31 PM 8/17/2009

[maxnix]

OOOOPS!! Quick answer on my lunch break. I got my NICO ECU in October or November last year. It was not doing this when I first got it, I don't recall ever using the a/c.

Whenever the HVAC is set to Auto, the AC is on.

[silkysmoothyjud]

Yes, when functioning normally. I have never used the a/c with the NICO ECU until just recently. I did not develop a problem (or noticed it anyway) until after I fixed the a/c belt and used it for a couple of days on my way to work and back (on break) and it got cold again. When malfunctioning, the a/c would engage and the fan would come on regardless whether 'econ', 'auto' or even if the climate control was unplugged. I never cared to fix the a/c belt for a while (months) since my commute is so short and we have had no hot weather until recently; now the summer is gone again. Its been a strange summer: 70 degrees today in St Louis. What?? Magnetic pole switch hitting the weather hard this year, but that is for a different thread. The only hot weather we had this year besides the last couple of weeks was in June, and my a/c belt and pulley were broken then. (go figure)
Modified by silkysmoothyjud at 8:00 PM 8/21/2009

[qsiguy]

Hey silky, did you try this NICO ecu on both programs to see if it would work in stage II or III? Also, did you at some point turn the diagnostic potentiometer dial while troubleshooting? Reason I ask is that it was turned all the way clockwise when I got it. That could make the ECU act strangely if you were operating the vehicle full time like that.

Everything else checks out, both BINs are complete with no corruption, I was able to pull them off the ECU and confirm they matched the NICO non tcs stage II and III bins. With the jumper connected the ECU is in stage II and with the jumper open it's in stage III. Is that the way you understood it? The chip/socket install looks secure with no obvious solder joint issues.

[silkysmoothyjud]

No. I was under the impression that if the wire is unhooked it ran the stage II program. I've been driving around with it unhooked the whole time (cold snappin necks on the highway 140 mph+). If the wire is connected, it is in stage III correct? Shortly after I got my NICO ECU, I did have an injector failure, and I was having a hard time figuring out which injector was doing it until it completely failed. I do recall swapping ECU's during that time, and running the diagnostic on both ECU's. I ran stock for a while. I may have checked the diagnostic on the NICO pute, pulled it, then put my OEM back in, self diagnosed it (55 on both) and forgot to put it back to spec.

[qsiguy]

....If the wire is connected, it is in stage III correct?...

No, with the jumper disconnected on this ECU it was in Stage III, so you have been using stage III all the time.

[silkysmoothyjud]

Im lucky I have good gas in my area (QT only as per Q45 tech), short commute and all highway driving then. It explains the fouled spark plugs I had over the winter, but no damage done, it still idles smooth as silk. I will keep it in stage II from here on out.....

[silkysmoothyjud]

Have you sent it back yet? I still have not received and info on shipping or anything from Wes as of yet. Please let me know. I miss that thing, my OEM ECU is soooo freakin lame compared to the NICO ECU. Thanks.
Modified by silkysmoothyjud at 4:43 PM 9/3/2009

[silkysmoothyjud]

Got an e-mail from Wes, I cant wait to get it back!!! Thanks for your help!

[silkysmoothyjud]

Just got it and installed it today. She runs better all the way around with that pute. Smoother shifts and a flawless idle. It is almost like the OEM is the wrong pute and the NICO pute was MADE for her.....

[elwesso]

so the AC works now?

[silkysmoothyjud]

I just went out and checked it. Everything is fine and I am in stage II for sure now. I have a quick unrelated question for you: Why does my car have better acceleration (stock ECU and NICO ECU) when the gas tank is half full? When I have a full tank, it seems to bog. I changed the fuel pump with a new OEM about 20k ago. Thanks for your quick response and unwavering support!

[Q45tech]

Measure the fuel pressure under acceleration.Sure it's not just the extra 75 pounds in the rear?

[silkysmoothyjud]

More than likely extra weight. It's slight, but noticeable. I will be riding around with a half a tank for now on. Thanks for the heads up!!!