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Auto_Enlightenment, Team Leader Tech
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Experience:  Honda Master Technician & ASE Master Technician
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2002 Civic: /C compressor cuts..randomly..speed sensor

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2002 Civic, manual trans: A/C compressor cuts out randomly and engine surges. Recently had "engine speed sensor" replaced and a small amount of refrigerant added. Seemed to take care of problems for about 4 weeks. Then A/C began intermittently not working, and today stopped all together on a 45 minute trip (cooling stopped, fan works) plus the engine surging returned. Any help?

Auto_Enlightenment : Hello there, I am a Master Automobile Technician certified by Honda and ASE. I can help you with the problem you are having with your Honda!
Auto_Enlightenment : Sounds like you have a couple things going on. Lets beak out down and deal with just the a/c for now then we'll address the surging
Auto_Enlightenment : When you a/c quits cooling, you say the blower in the cabin still blows correct?
Auto_Enlightenment : The next thing we need to check its the fans in the engine compartment and the compressor clutch. When the a/c is on both fans should run and the a/c compressor clutch should cycle on & off at pretty regular intervals.
Auto_Enlightenment : If the compressor clutch does not engage and spin when its acting up then we could be dealing with any one of numerous possibilities which I will walk you through checking.
Auto_Enlightenment : Since it works for a while before quitting we need to check that the evaporator or expansion valve its not freezing up. You would check this by looking at the large aluminum line going into the passenger side of the firewall/bulkhead. This line should be ice cold and wet with condensation. If the condensation is actually frozen then the system is freezing up and again we are dealing with any one of a few possible problems which I can walk you through checking.
Auto_Enlightenment : If a system is freezing then it will start working again as soon as it sits and thaws out.
Auto_Enlightenment : For now, check the fans in the engine compartment and look to see if the. compressor clutch its engaging and spinning with the pulley
Auto_Enlightenment : Let me know what you find them we'll proceed accordingly. Thanks.

Response to your Q's and update:


The A/C compressor is not cycling on.


The fans are working (both)


The blower fan works


The refrigerant line is not frozen, and not cold at all


Additional - Turned the A/C off and the engine surging stopped. Turned the A/C on, the surging started again plus the Alternator light came on, and the engine stalled. Turned the A/C back off, and the surging stopped and the alternator light went back off.


Additional (2) - Recently (about 4-6 weeks ago), some of these same symptoms came up. I took it to a auto shop where the alternator was replaced, an "engine speed sensor" was replaced, and a small amount of refrigerant added. (I'll have to look at the repair receipt when I get home tonight to let you know the exact name of the sensor).


Correction - NO sensor of any kind was replaced, just new alternator and additional refrigerant. My mistake - sorry.

Auto_Enlightenment :

If the engine drags down and wants to stall every time you turn the a/c on then I suspect your compressor is seized up. It's a tight fit but to check this, with the car off you need to either reach down and try to turn the compressor clutch by hand or use a long object to stick down there and prod at the clutch to see if it spins. If it will not spin then this would confirm that the compressor is seized up.

If the compressor is seized up then every time you turn the a/c on it will act like a brake on the belt which is attached to the motor so it in turn acts like a brake on the motor. If the motor is having a hard time turning against this belt resistance then the alternator will not have the rpm's it needs to supply voltage and the motor will have a hard time running.


Thanks for the quick response. Here is about all the information I can think of.

The car surges when I take my foot off the accelerator pedal.
Scenario: Driving along at whatever speed (usually the rpm is 2000 or higher when I'm driving, often get above 3000 rpm before changing gears). Approach a turn/stop sign/stop light/parking and take foot off the pedal. RPM drops to ~ 1000 rpm, then suddenly revs up to 2000 rpm. If I'm turning, it usually just goes back to working normally in the 2000-3000 rpm range. If I'm stopping, it'll stay at this elevated 2000 rpm for up to 20 seconds (sometimes just 5 seconds when it's 'better'). Then it'll suddenly drop to ~500-700 rpm. If I'm really unlucky, it drops so fast it falls below 500 rpm and stalls/almost stalls/triggers the alternator light (which will then turn off after driving normally for ~ 30 seconds).

When it was behaving that way today and I turned off the A/C, it started behaving normally. After stopping successfully at a stoplight without surging (sitting there maybe 30 seconds), I turned the A/C back on. The engine suddenly revved to 2000 rpm (it was not in gear) for 10 seconds, then plummeted to 400 rpm and sputtered a bit, then recovered to 500 rpm and the alternator light came on. I immediately turned the A/C back off. After I drove through the light and changed to third gear (revving ~ 2500-3000 rpm), the alternator light came off. Pulling in a parking lot and parking produced no more surging.

On the way home, I tried this trick again, but there was no more surging to be had and the A/C is still not functional. I won't be able to diagnose the surging more at this point.

In the last three weeks, I've had two sessions of surging which lasted 1-3 days (up to 2 hours worth of driving). In general, the A/C has gone off ~50% of the time. I have been keeping it on trying to diagnose when it goes off and on.

The very very first time the A/C didn't work, I was driving along at 65 MPH just fine in 80 degree weather starting a 3 hour trip. The A/C started blasting hot air ~ 15 minutes into the drive and never came back on. The next day when I started my car, everything was normal. This last time the A/C worked (Friday), I drove 1 hour and it was fine the whole time. Then on my way back, the A/C cut out 20 minutes into the drive. It hasn't been on again, for 5-20 minute drives, except for approximately 20 seconds today in the middle of driving along at 45 MPH at 2000 rpm. I was driving home at 65 MPH on Friday, so I didn't notice the surging until I got to a stoplight after 1 hour of driving (aka ~40 min after the A/C died). The other surging episode started immediately after I picked up the car after the alternator was replaced.

The car sounds and looks fine to me whenever the surging is not occurring. The drive belt has been checked several times by auto shops and I'm told it is just fine, tension o.k., no signs of slipping or burning, and no squealing.

Unfortunately, I can't replicate any of this on command. So it makes it doubly difficult for a technician to diagnose. Please send any more questions that will help you.

Auto_Enlightenment :

Thanks for all the info, every little bit helps in diagnosis. Let me think about this and see if I can come up with anything but this may be one of those things where you need to leave your car with a technician until they can duplicate and diagnose it. These sporadic problems can be the most difficult to solve. Often times we are forced to wait until the problem is so bad that it exhibits itself consistently enough to be diagnosed which can of course be frustrating with all of the uncertaintly.

Customer: I understand. I'll hold on for a bit before closing the question. Thank you.
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