Problem: AC turns off and stays off even if restart

matteni

matteni

Legendary Member
Joined
14 April 2002
Messages
2,273
I have a problem that just developed. Any insights / guesses appreciated!

I start the car up and the AC turns on and I can fully adjust the temp, fan, etc. Basically after a couple of mins the control panel goes completely blank, the AC is turning off, the fan is turning off, and everything is staying off unless I let the car sit for 5-10 mins with the ignition completely off.

This is getting pretty repeatable now.

Weird side comments:

- The last time I started the car the volts were jumping between 11-13 and the AC display was going on and off before going off. Once the car settled into idle the volts settled in on the high side 14-15.

- I have had a similar thing happen with the driver's side window where it stopped responding and then started responding once I took the key out and restarted.

Here is what I know:
- All the fuses are fine
- Using 4 year old Odyssey 545 (seems OK still / starts the car)
- Original AC / controls (*did replace compressor 3 years ago)
- AC blows cold when it is on
- Climate adjusts well when it is on
- Fan works at all speeds when it is on

any ideas???
 
This is just a guess but I would check to make sure your battery cable connections are good and tight. If you have a loose battery connection all kinds of weird things can happen.

Bruce
 
OK - a little more information...

Tonight I did an experiment - basically the volts are going up with revs and so is the fan. Also - I did not run the stereo and the AC never turned off. Also - it only turns off early in the run - if the car is well warmed up - it stays on.

I am starting to think this is a battery issue as the volts are not holding and varying with RPMs and it is causing the fan to do the same.

Any input into this theory? Would a warn out battery cause the fluctuation in volts with RPMs and cause the fan to speed up / slow down with RPMs?
 
Hi Nick,

I would remove the alternator and have it bench tested. That is assuming that the alternator belt is the proper tension, and you checked as Bruce suggested and the battery terminals are OK. The voltage regulator is integrated into the alternator and it sounds like you have no voltage regulation now.

I am not sure a bad battery would cause the fluctuation, however a bad battery could have caused the alternator to go south, so definately load test the battery too:).

HTH,
LarryB
 
If you find out that it is a bad alternator let me know, I have a new one I got when I did a supercharger install I will sell to you at a good price. Another thing to check is the ground strap from the body to the rear valve cover (depending on year) and the connection at the alternator. Not many of these alternators go bad.

Bruce
 
Hi Bruce,

Thanks for your post.

I am trying to save $ and would like to do some leg work myself - albeit I am not the sharpest knife in the drawer when it comes to electrical (or much else for that matter)!

I have a 91' - does my car have this strap and if so where is it and how do I test it. Also - I have a voltammeter. Is there a way to easily remove and or easily bench test the alternator?

Can I remove it and bring it to any shop?

Just trying to get away from spending big $$$ at my local Acura dealer.
 
There is a ground strap that goes from the body to the front valve cover nut on the transmission side of the cover. If the car runs you can take to a local parts store (Auto Zone or Pep Boys)and they will check it for free.

Bruce
 
I went to AutoZone and it appears to be my alternator (or more specifically the regulator part of the alternator). They were very friendly and interested in the NSX. They even quoted me a replacement Beck/Arnley #186-0648 110 Amp new alternator for $282.85 (after core exchange). I am trying to source a local Acura 3.0L used alternator in town from a friend (at least to test and maybe to buy).

Bruce - please PM or email me at [email protected] and let me know how much you are looking to get for yours as I might be interested in a new one if it turns out that mine is truely bad.

Thank you Bruce/Larry/all for your help...
 
Nick,

I just saw this thread but responded to your email earlier today.

Larry, I got the summarized version of this via email today and suspected worn brushes in the alternator as my first choice and the regulator as my second. Seems like brushes could account for the voltage fluctuations even if the regulator was OK because it would not be putting out enough at low RPM to make minimum voltage. But, if the volts sometimes climb above normal max then my guess shifted to the regulator. What do you think? Have you ever had an NSX alternator apart? I'll give Nick one of my spares and if that solves it I'll take the old one apart and attempt repair.
 
Hi Steve,

I am pretty sure it is at least one of the diodes, maybe two:). To me it seems the alternator is not putting out full CURRENT. Once there is a large demand (blower motor, etc.) the voltage dips since the alternator cannot deliver the proper amperage. Usually this is an open diode(s) in the recifier curcuit. Ohm meter will test it easily if you have it apart. I am pretty sure there are 6 diodes, but it could be 9. The other possibility is that it is all sealed up in a module and you will need to replace it. I do not think you actually have "brushes". I think it has "slip rings" which are pretty durable.

NO, I never had an NSX alternator apart, but many others:).

HTH,
LarryB
 
Larry Bastanza said:
Hi Steve,

I do not think you actually have "brushes". I think it has "slip rings" which are pretty durable.
Click to expand...

Thanks Larry, that's why I asked you. I was focused on the fact that bringing up the revs a bit seemed to stabilize it and that sounded like worn brushes making spotty contact, but from what you say they don't even exist as such anymore. But I haven't had one open in many years myself and those were stone old already at that point. At least my second guess was correct, but mostly because in an email Nick had suggested that the voltage may climb above normal when revved.

I'll post what I find in terms of replacement parts. I'd guess I'll need at least a full diode pack since they're sealed in a module for their own protection from heat and vibration.
 
Well - good news and bad news!

The good news is the alternator works fantastic! The windows work great, the volts are rock steady, and the fan does not adjust with the RPMs.

Bad news is the climate control still goes dead some of the time. It will work and then all the sudden - will completely shut off. No lights, no fan, no buttons, nothing.

I can turn the car on and off - won't help. Only if I leave the car for a 1/2 hour or more that it will work again.

It also seems to be related to temperature. The lunch runs are the worst - it seems to shut off on it's own more often during the noon day heat then at night or in the mornings.

I did some searching and it sounds like some people have had bad capacitors - coud this cause something like this...

Bummer - thought I was home free but I just uncovered another layer in solving the problem.

Anyone have an extra climate controll unit too! :D
 
OK - I'll keep posting to my own thread for posterities sake! Besides - I am used to talking to myself!

:)

I did a lot of research on this site trying to figure out if my problem on my 91 is the TSB listed here: http://www.nsxprime.com/FAQ/Reference/tsb/92-007.htm

or is it the climate control unit listed here: http://www.nsxprime.com/ubb/Forum1/HTML/001329.html

Here is a great post with pictures: http://www.nsxprime.com/ubb/Forum10/HTML/000826.html

One poor sole even got charged by his dealer $4,000 to fix this! I figure a new climate control unit is about $1300 from the dealer or $700 discounted. There are used ones to be had for about $400 and there are places that will attempt to fix the electronics for $100 + 2 way shipping + tax (call it $150 or so). Gerhard Languth who has fixed several climate control boards for NSX owners actually does mostly car stereo repair and many NSXers reported success with his shop and he charges $100 + 2 way shipping + tax.
Here is Gerhards info:

Langguth Electronics
711 East Parkway Dr
Russelville, AR 72801
479-967-0873

I choose to use a company right across the street from me in St. Louis (actually Manchester) Missouri. They are going to charge me $90 labor + part costs and will need 3-5 days to do the work. I was able to pull the control unit with the service manual pages (very EASY - only took 1/2 hour on my first try). I brought it to Joe Landmann at ATech Industrial Electronics, Inc.

ATech
429 Sovereign Court
St. Louis MO 63011
Toll Free: 877-870-5777 x302

Joe pulled the board apart and quickly found 2 of the 13 capacitors that we could visually see were bad. He is going to replace all 13 and then test with 12v DC to make sure it works. We can then re-install it to make sure it isn't one of the transistors too.

If this goes well - I can recommend them to local folks or others needing faster turnaround then Gerhard (quoted me 2 weeks +). Also - most of my down time is ordering the parts (which Joe said he can stock if others need this repair). As for the equipment they use - it seemed very professional and even has a little vacuum on the de-soldering device (ok - maybe you all knew this but I was impressed with how professional/clean the work area was and how new all the equipment looked).

More next week - darn is it hot with no fan and no AC!

Here are some key words in case anyone is doing a search:

climate control problem
climate control repair
AC shuts off
climate control on and off
climate control turns off
climate control quit working
 
I talked to the tech on Friday - apparently we had miscommunicated a little. He was in contact with the original mfg of the capacitors "Nipendeso?" or something like that. Anyway they have not made those exact capacitors for many years and the parts where expensive. I told him just to order and replace like with like and don't worry about the manufacturer.

Also - interesting to note - the mfg warned him these capacitors should only be used in applications up to but not exceeding 106 deg F. This is interesting because it is hotter inside my car almost every day! Why would Honda use such capacitors is another matter. Maybe these problems are happening to daily drivers or in hotter climates?

Anyway - I should have everything back together by the end of next week.
 
Last night ATech here in St. Louis gave me back my climate control unit. I must admit the soldering and traces looked VERY professionally done. I asked them how much and how I pay and they said - "I'm not sure yet - just take it and we will send you a bill for the total". They said the hardest part was finding the exact replacements as they were odd capicitor values (at least compared to what they are used to).

This morning I put the unit in, took a minute to clean out the fan next to the hand brake, and put the dash back together and - whala! Everything now works perfectly and the AC never felt so cold!

They estimated 1.5 hours ($90) + parts before the job started so I will let you all know the grand total when it all comes in.

That all said I am very happy I figured this out and was able to have it fixed myself - saving thousands compared to what some people had to pay replacing parts from the dealer.
 
Nick, welcome to the (I fixed my head unit myself club)....and saved big bucks. mine is still blowing ice down here in FL heat in august. I have several other dead head units that will soon be brought back from the dead.:D
Best Regards David
 
BadCarma said:
Nick, welcome to the (I fixed my head unit myself club)....and saved big bucks. mine is still blowing ice down here in FL heat in august. I have several other dead head units that will soon be brought back from the dead.:D
Best Regards David
Click to expand...

Thank YOU David for your fantastic posts and for being such an asset to this board. I don't think I would have had the courage to do this if it wasn't for much of your information/pictures.
 
DARN IT!

:(

I jumped in my car today after several hours of perfect AC and I'll be damned if my Climate Control wasn't dead!

Again - it seems like it is a middle of the day thing for some reason. I do know my alternator was bad, I did repair at least 2 obviously bad capacitors that had leaked onto the board and the traces where repaired. I also replaced all the caps just to be sure. So I feel good about what I have done so far but I figured I would be done at this point like so many others reported they where.

So - what else could it be?

- could this be related to the TSB on the blower motor (my fan seems to work fine at all speeds when the climate control isn't dead)

- intermittent wire problem?

- should I replace some/all of the transistors on the climate control board?

What would make this thing be dead or alive, why does it seem to stop working for an hour at a time, and why does it start working again after the car has sat for a while?

Entertaining any logical guesses at this time...
 
Nick,


Is there any relays on the circuit board? If the circuit board have relays you might want to replace it. Relay can cause intermittent problem. Just a thought.



Tony
 

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