i have spent a considerable amount of time trying to see if someone had a similar question, but in vein, so i am gonna ask it:

i have a 93 R1 with 69K miles on it. its in good condition, and pulls hard with both turbos. recently, a problem has developed. with my a/c on the idle oscillates from the normal idle of 900rpm. the oscillations get stronger and stronger untill the magnitute of the oscillation is equal to 900 rpm either way at which point the car stalls. when the osciallations begin, if i turn the a/c off the oscillations stop. to test the connection of the a/c with the oscillations, i monitored the switch section in the power fc and observed that as soon as the pfc would show a voltage across the a/c swich the oscillations would begin, and as soon as the a/c switch shows that the voltage has stopped, the oscillations would stop. btw: my understanding is that the a/c is regulated by a thermostat so with the a/c button pressed it, its possible for it to be shut off (of course the fans are on at all time).

anyways, if anyone has an idea of what i am talking about, could you please tell me if you know how to rectify it? it seems like an excessive electrical load. could it be caused by bad grounding? or could it be because i had a faulty fuse or something?

please let me know.

-bilal

 

I think I have this same problem. It doesn't happen all the time and for about a week it never even did it but now it started again, it started happening after I install my FMIC, it won't do it when the car is warming up and the A/C is on, or even after I have driven it for 10 minutes or so but then it just happens randomly.

 

mine doesnt happen randomly. it happens consistently while the a/c is on.

 

i've had the same problem for a while. someone told me it had something to do with the egr valve, so i got a new (used) one. didn't fix quite fix it though. one day i was at a light and just let it sit there, it eventually got less and less (long light), and then my idle smoothed out. i dont know if its a pfc problem or not. do you guys have a pfc too? my buddies fd just started to do it. i'd mess with it cause it drives me nuts, but my car has been in the shop for 3 months now. how can we fix it guys? maybe it has something to do with the pfc, i noticed icemastr has one, i do, my buddy does, and if redrotaryrock8 has one, maybe thats a start.
shaun

 

I had the same problem. Very embarassing. I got pissed and took it on the highway. Left the A/C on and floored it for a good while. Really thrashed it with the A/C on. No problems since.

 

What actually happens when you turn the AC on?

Maybe it's an electrical load problem or something, kinda like I'm having.

 

Check your Clutch switch, if it is bad, it will cause the car to idle lower, and almost die when the A/C is on. Just a thought.

 

Did u guys change the freon on the car? I know they came with R12 and the 95 comes with R134? Btw my car does it and I point it to the a.c. compressor is locking up after it run for a good 15 minute smooth and then the idle bounce around and the car the die {shut off}. I made a big mistake by replacing my freon to R134 and not doing it the right way cause my a.c compressor to act up. Also I rarely use a.c. since I had my car in 96 I only use 3 times and I think if u don't use the a.c. alot like me and my car park up for winter I guess the compressor will die someday.

 

it feels like an electrical load problem. i will try thrashing it on the highway with the a/c on (although i do it all the time).

its definitely an electrical and not a mechanical problem, and i can say this because of the perfect harmonic oscillations that the idle records.

i will try changing the clutch switch, my suspicion is that it has nothing to do with the clutch switch because the car would do it regardless of whether the clutch is in or out.

any other ideas?

-bilal

 

bump

 

How is your grounding? My problem is just like yours and in the next few days I'm going to add grounding straps to 4 or 5 locations around the engine bay to see if that helps.

Does the same thing happen with the lights on, and the car in gear (clutch in)?

 

yup, it happens regardles of what i have on or what i have off.

the idle starts to oscillate as soon as the pfc records the a/c switch as turned on.

 

bump

 

i have the same problem, KD rotary diagnosed it as an internal pfc hardware problem. could be, anyone try replacing the idle speed control?

 

i got the exact problem as you Rx7aholic, whenever i turn my ac on when car is fully warm-up..it stal or die from stationary position to throttle position < or hesistate> before i though dat mght be a TPS.. or Apex seal blew.

 

That is what I have heard also. It's the PFC version.

 

pfc version as in software or hardware king?

 

Not sure because I do not own a PFC but there is different model versions. I'am guessing the hardware because you can't interchange commanders with a different version of the PFC.

 

i think its hardware too. oh well, i only rarely use the AC and thats on the highway so no issue.

bought my pfc from SR motorsports back in 2001, how bout the rest of you who are having issues.

 

I had this problem. I found that the clutch switch was the cause.

 

Check the hi side pressure on the A/C. If there is an exess load against which the compressor has to work to start when it cycles, it creates a drag against the drive belt and can stall, or nearly stall, the engine. If the pressure gets too high, the hi pressure cut-out activates and frees up the compressor. This gives the surging idle speed effect. The excess pressure can be caused by an over charge of refrigerant or contaminants in the refrigerant. Not sure what the exact pressure for this to happen could be, since the overall condition of the compressor will be a factor. With most of the FDs getting older, there are a lot of compressors out there that are now only operating at 50-60% of their original efficiency. In my case a new compressor fixed the problem. Short of replacing the compressor, you may want to replace just the receiver/drier after a pressure flush to clean out any crap in the system. If you have changed to R134 without doing it the proper way, this may be the problem anyway.
Ron A.

 

how much would it be for a new compressor.

btw: if i increased the intensity of the a/c the a/c stops cooling all together. i have to keep it at 1.

i will try the clutch switch and will post the findings on this thread.

 

A new compressor will run $350-400, depending where you buy it, plus installation, if you do not do it yourself. Re-built should be slightly less. Ron A.

 

I like this idea. I know my clutch switch is bad and my a/c doesn't make the idle oscillate but just makes it stall at stoplights. i'll have to look into this.