Problem: AC turns off and stays off even if restart

[sjs]

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

Excellent thought. That could account for the distinct on/off nature of the problem, assuming there are any relays involved. Check the wiring schematic because they may not be on the board itself. I have the wiring supplement to the factory manual (somewhere) if you don’t have one.

 

[matteni]

Thank you SJS / Tony - I will check on that.

It seems now that when I turn the car on it blinks on and off for the first 5 seconds - and then mostly stays on after that.

Weird...

I have the electronics supliment (and it is on-line) so I will let you know for posterity's sake.

 

[KGP]

I have the electrical manual if you need it Nick.

 

[matteni]

I have the electrical manual if you need it Nick.

Thank you KGP - I will let you know...

 

[Larry Bastanza]

Hi Nick,

Before we go blasting ahead, lets look where we have been first. I have one major question: Does your voltage gauge act wierd, like it did before, when things go bad with the CC? I am trying to understand what we may have/have not cured.

Remember Bruce mentioned his stats on alternator failure, very low. Maybe the AutoZone guy missed a step, and you are actually at square one.

Let us know.

LarryB

 

[matteni]

Hi Larry / SJS / Other interested people,

Here is where we are at as I worked on it more tonight...

First of - the voltage is now rock steady from start to 8k RPMs so I think the alternator problem has been resolved. Also things like the windows are working MUCH better meaning they go much faster then they did.

Next - there is the capacitors on the climate control. I don't know for sure that the 13 caps where replaced and that the parts were not defective. So that is still debatable.

However - I did try some tests.

First I hooked up a battery charger and did all my tests without starting the car (removing the alternator as a probable cause).

When I first turn the ignition on (but not all the way to start) there is a noticeable delay in the lights on the climate control coming on (maybe a second or two and varies a little). Usually after this hesitation - the lights and the fan turn on for a second and then go black / back off - then after another second or 2 - back on and they stay on indefinitely (several mins to however long the drive is). This held true with just the fan on and the car not started during my test (repeatable).

I can now pretty much replicate getting it to turn off too. In the driveway with the car on but not started - if I turn the fan on the highest setting and then pump the brakes I can usually get the climate control to go black and the fan to turn off. So it does seem dependent on electrical load and is definitely related to fan speed. The higher the speed of the fan - the higher the probability the climate control will shut off at some point. The probability goes up as additional loads are placed on the electrical system.

I am starting to think this is related to the fan relay and or the things in the 91 TSB on the fan controls.

Thoughts? Anyone have a spare "known good fan / fan control / fan relay?

Thanks - the hunt continues!

 

[Larry Bastanza]

Nick,

I am thinking that most fo the capacitors in the CC unit are used for power filtering. That means they are connected from +12V to Gnd. If so, their job is to keep the power all nice and clean. Do you know if he actually replaced all 13, could he get all the sizes?

It still sounds like a voltage problem internally. Admittedly there are many things that can cause this, but the caps have had a prefect track record as the culprit with these units, best I can tell.

The TSB related to the fan basically running on "high" only, so I am thinking it is not applicable here.

HTH,
LarryB

 

[matteni]

Hi Larry / others,

Well spent even more time on it this weekend. I basically did the electrical manual troubleshooting flowchart testing for voltage and continuity on the 30 pin connector. Everything checks out from basically a "yes there is volage where there should be" and "yes there is continuity where there should be".

I then wanted to remove the alternator as a potential cause so I hooked up a heavy duty battery charger, cranked up the amps to the battery so it wouldn't die, and turned the key all the way over (without starting the car) so I could try to get the climate controll to quit repeatadly.

I wasn't able to get it to quit and just left it running so I could do other things.

Then I decided my Razo drilled pedals where to close together and the gas was too high for heel & toe shifting so I went to work on the gas and brake pedals when the AC fan went off. It seemed rather repeatable that with the fan on high and with a pump of the brakes I could get the climate controll to shut down.

BTW - it was over 100 all weekend and with a black interior and no fan/ac it was boiling!

So I call the guy who did the electrical work for me and ask him if he is sure he replaced all the caps correctly? He said he did. I checked his work and the polarity all looked fine and I couldn't see any problems. I asked him if there was anything else he could attribute the problems too and he couldn't. Of course it was running fine that minute! I then told him about the brake light getting it to turn off as if it was related to load and/or heat or something.

He remembered that the largest input power to the board is a 15 amp fuse from the tail lights / brake lights. I said huh? He asked me if the panel dims when I turn on the headlights and I said it does. He asked if there was a relay on these lights and I said there is.

He asked if I could swap with another one on the car and I said I could.

This is hopefully the clue I was looking for! More info to follow. Shoot holes in this theory if you have any ideas / info.

 

[KGP]

Nick, you are well on yor way to establishing yourself as the StL go-to guy for AC trouble-shooting.

 

[jrehner]

correct me please

i seem to remember a thread about dimming of the display when putting on lights which apparently is somewhat the norm--there is nothing wrong with my climate control but my panel lights on the climate control et al will get dimmer when I turn the headlights on. There may be some fix for that--people also change the color of their displays--I think D'Ecosse may know something about this and the dimming aspect...or know who does...

 

[matteni]

well - don't know if it is related but my battery died over the weekend. Picked up a new one and need to get it installed to see if this helps at all...

 

[D'Ecosse]

Re: correct me please

--I think D'Ecosse may know something about this and the dimming aspect...or know who does...

Thanks for the vote of confidence!
The panel lights are supposed to dim when the driving lights are turned on - reason being, they need to be brighter in daylight, but not glaring at night. There is a an input on 14-12 on the A/C climate control unit for this function, originating from the dash lights brightness control unit.

Nick - see if you can measure the voltage at pins 30-11 & 30-30 when you do your brake pedal test - you can also check these at fuses # 38 & 33 respectively - these are the voltage inputs from the tail-light relay & battery, again respectively .
Does your battery volts hold up when you apply the brake pedal anyway? Possible short somewhere in the brake-light cct sinking current & dropping the volts to the controller - possibly even a bad bulb.
If these are holding up I would suspect still something amiss in the controller - I wish I was closer, I'd be glad to let you try my controller - no-one closer who will consider a temporary test?

 

[D'Ecosse]

well - don't know if it is related but my battery died over the weekend. Picked up a new one and need to get it installed to see if this helps at all...

so what's the conclusion to this story - was it the battery?

 

[matteni]

unfortunately not.



still working on it and going to be gone for 2 weeks but then I have a doner lined up to let me troubleshoot further.

Thanks for checking back!!!

 

[DanO]

Nick, I know this sounds crazy, but give your test a try with the interior dash light pot (knob) in the max bright position and then give it a try with the pot in the full dim position—it will probably not make a difference but I’d like to know for my own knowledge. Next, you may want to try and use a length of wire to ground the unit directly to the negative terminal on the battery to rule out a grounding problem.

These electrical problems are a real pain to trace down!

Good luck,

DanO

 

[matteni]

great tips DanO - I'll let you know!

 

[matteni]

Damn thing is going to cost me my sense of humor!

I haven't had AC working in 2 days and today at all and I went out to run some test and you guesed it - working perfectly.

Couldn't get it to turn off with the dimmer, brake pedal, radio, or other electrical on/off. Also let it run 15 mins and everything was fine.

I am interested in the "ground" test - perhaps when driving it is "shaking" or something? Are there any relays tied into this thing (I couldn't find any!)

 

[jbrand]

I experienced many of the same symptoms you have been describing.

My climate control system failed intermittently. I knew it wasn't a loose wire--at least, symptomatically, it didn't appear to be.

I could be idling at a light and the AC would falter, go off for several seconds, then back on and run perfectly for the rest of the day. Other times, it would fail and stay off for the duration of the ride. No consistency.

Then it failed for good. No amount of coaxing, resting, praying was getting it to fire up again, even intermittently.

After reading this thread, I decided to pull the PC board for the climate control. Found a couple of suspicious capacitors; they'd leaked.

I took it to a local electronics guy (someone whom I'd given a ride in the NSX and who LOVED the experience). He said he'd try to fix it for me.

He replaced ALL 13 caps, noting he wasn't sure if the thing would work or not because some of the traces had been eaten away by the leaking caps. He rebuilt the traces as best he could. He also indicated he put higher-temperature-rated caps back in.

Reinstalled and voila!!! Ice cold air. The "FULL AUTO" works like a charm.

Paid the guy $75 for his time. The cheapest fix I've had on the car!

Jeff

 

[matteni]

After spending over $100 trying to replace capacitors (worked for a couple months) and then $586 on a new climate control board - finally it is working like a champ.

Thank you to Dali Racing / Cush Acura for a great discount on the new board.