avinoam83

I've been borrowing my parents' 96 Civic for about a month. I live in NYC, so I don't currently own a car. Last weekend, I left the car running for about 10 minutes, and when I came back, the AC system was blowing warm air. I took it to a mechanic who added refrigerant and replaced the fuse for the condenser/compressor fuse. Once the fuse is replaced, the AC blows cold air, but the fuse blows in about a minute. The mechanic says that the fuse blows because the compressor clutch is overheating. He offered to replace the compressor to the tune of $1076 (parts and labor). He said that it's not worth replacing the compressor clutch alone since it would still require evacuating the refrigerant from the system and so I wouldn't save much. I declined and took the car home after paying about $150 for the refrigerant refill.

I put in a new 20A fuse and the fuse indeed blows after the compressor comes online for a minute or two. I put in a new fuse and removed the compressor clutch relay. I left the car running for 5 minutes during which the condenser fan seemed to operate normally and the fuse didn't blow. I then replaced the compressor clutch relay and removed the condenser fan relay. I started the car and the system blew cold air, but after about a minute, I started hearing a squeaking sound which I assume came from the compressor. The system soon stopped blowing cold air, so I checked the fuse, which had blown. It seems to me that this does implicate the compressor / compressor clutch. I have a few questions:

1) How do we know that the compressor clutch is failing and not the compressor itself? Couldn't a failing compressor cause the compressor clutch to overheat and blow the fuse?
2) Is it possible that the squeaking sound was caused by the compressor running without the condenser fan?
3) Is it true that the refrigerant needs to be evacuated in order to replace just the compressor clutch? I've read that it's possible to replace the compressor clutch without totally disconnecting the compressor (removing 3 out of 4 bolts), but I'm wondering how practical this would be.
4) The mechanic said that I have a Denso compressor. I looked online for a compressor clutch and the parts that I'm finding seem to be for a Sanden compressor. Would a Sanden-style compressor clutch work on a Denso compressor?
5) Can I replace the compressor clutch without getting under the car? How hard would it be? I've reviewed the service manual, but it's not showing me what parts I need to remove to get to the compressor. I'm new to working on cars, but I do have a fair amount of technical skill.

Thank you!

sumdewd

The field coil for your compressor is most likely shorted out because the insulation is compromised. I had the same problem happen with my 91 Civic. You need to grab a multimeter and check the resistance from the compressor's red wire to a good ground. The resistance will be much lower than usual. I unfortunately don't have access to a shop manual right now to show the correct spec.

1. A bad compressor usually results in poor cooling and/or horrible noises. The job of the clutch is to toggle the compressor on and off with an electromagnetic field coil. It will overheat if shorted out (insulation gets old), or if the clutch is slipping. I have seen clutch plates with a tempered glaze on them before from slipping.

2: Absolutely. Would not recommend ever doing that again. Too much high side pressure and you risk blowing a hose or a blowout plug. The compressor is working much harder when the high side pressure is not in check, which might have made your belt squeak.

3: Only if you remove the compressor from the car. If you can jury rig stuff from under the car, then sure. I've done it both ways and there isn't really a way to win. Two seconds with a snap-ring outside of the car VS an hour of cussing under the car while crap is falling into your eyes. The advantage of doing it without evacuation is not having to pay the A/C guy again.

4: I don't know if the parts cross-reference, but I wouldn't recommend trying to find out the hard way. Do some more research. Car bodies tend to rust out before the car is totally dead in NY--- Can you visit a salvage yard? Also, Amazon tends to have dirt cheap compressors for less than a new clutch would be.

5: Compressor clutch without getting under? Yes, if you discharge the system, undo/move power steering components, remove condenser for room to work with then you have access to remove the compressor to service the clutch. I honestly don't think it's possible to do the clutch from above the car without discharging since the condenser and hoses are REALLY in the way.

1k for compressor replacement is kind of ridiculous. The 96-2000 Civic is super easy to service. I was able to replace the compressor in the wifey's 96 Civic by jacking it up, removing the driver's wheel and torque mount, then started unbolting compressor stuff. You may also be able to undo 2-3 bolts and swing it around to have access to the field coil under the car. Just be aware the goddamn snap ring is a PITA if you're doing it in the car.

avinoam83

Thanks for the super detailed response!

1 and 2 - I was also thinking (based on my Google searches) that it was the field coil. I have an old Radio Shack analogue multimeter. Can I access the compressor wire from the top of the car? Would the compressor even start up if the field coil was bad? I found the spec in this link:
https://honda-tech.com/forums/honda-...owing-3079480/
That's where I got the idea to unplug condenser fan and compressor clutch one at a time. Did I incorrectly understand what they were suggesting? It doesn't look like I can replace the field coil without disassembling the compressor clutch, so if the field coil is bad, I might as well at least replace the compressor clutch.

5 - I will need to find a place to work. I can't put the car on a jack in the city, so the preference would have been to work from the top. However, probably my biggest preference would be to not discharge the system since this would require me to bring the car to a mechanic twice - Once to discharge and one to recharge. So, under the car it is.

3 and 4 - I agree that based on the cost of parts alone, it's absolutely worth replacing the whole compressor. The issue is having to discharge and recharge the refrigerant. If I need to discharge the system anyway, I'll just replace the whole compressor.

sumdewd

Yup. Looks like reply #9 in that thread shows the correct specs. 3.05-3.35 ohms at 68f. Yes, as long as you don't have gorilla hands you should be able to reach the compressor connector. Probe the red wire and check it against a good ground. I honestly recommend a digital multimeter, but see what you get with analog. A shorted field coil will use more power than it's supposed to for the same job. Compressor clutch air gap is what will prevent the compressor from engaging, or possibly staying engaged when the car warms up.

The directions in that thread seemed incomplete. If you unplug the condenser fan, you better have a box fan or other mode of cooling going, or shut it off quickly. The system does have safety precautions in place to prevent damage in most situations, but it's best to not find out if they still work.

The field coil is behind/under the clutch pulley. The idea is it creates a big enough magnetic field to lock the outer hub to the belt-driven pulley to start turning the compressor.

Do you even need to fix the A/C right now? You maybe have another couple weeks of heat in NYC, then it's cold as ***** until April-May. It would give you enough time to sort out a proper repair location and source your parts. If the compressor is coming out, see about replacing the torque mount at the same time. It's almost always grenaded by now and causing some vibration. You will also need a new receiver drier if you're doing a new compressor.

avinoam83

I definitely have gorilla hands, but I'll see what I can do. I should be able to track down a digital multimeter. Do I need to unplug anything (power to compressor or battery) before probing the red wire? Would an air-gap cause the fuse to blow? You're right that I may be OK without AC for a while. The weather has been weird, so we'll see how long it stays warm. At this point. I'm kind of excited to do the work since I haven't done anything like this in a long time. Will the official service manual be a good reference for me, or should a newb like me to looking at a Haynes or Chilton manual?

Thanks again.

sumdewd

Excessive air gap would not cause the fuse to blow. The most common symptom of excessive air gap is the compressor clutch disengages after warming up. No blown fuses, no leaking refrigerant. It simply loses the ability to lock the outer hub to the pulley. Your condenser and blower fans will still run, and you'll have battery voltage at the red wire.

The official service manual will always help you. If you can 'acquire' the manual, and you plan on keeping the car for a while, then do so. Just make sure your frame or suspension isn't rotted out before you drop money on it since it is in NY. Reading a Haynes manual is like listening to your great great aunt Moe talk about how much she knows about computers. Just... Don't do it.

As long as the car is off, you really don't have to undo the battery. I mean, it's a good precaution, but do you really enjoy redoing your radio presets every time you sneeze on an electrical part? There's nothing that's 12v hot at all times on the compressor itself. It's all switched, and I really hope you don't have your hands down there while the car's running lol.

tamboo

sent you a link to helm manual.
have fun. 8)

tony_2018

if it is indeed the cltuch on the compressor why not replace the clutch

avinoam83

So then air gap isn't the problem. I actually do have some rust issues - There's a hole from rust on the right rear wheel well and some more rust on the left rear wheel well. I haven't seen any rust under the car but I haven't carefully inspected it.

I do have the official service manual, but I find that it doesn't include all of the information that I need. For example, it doesn't tell me what parts I need to remove in order to get to the part that I'm servicing.

avinoam83

Thanks!

avinoam83

I'm considering doing that. I just ordered some tools and jack stands and am trying to figure out whether I'm skilled enough to replace the clutch without taking out the whole compressor.

avinoam83

I'm having trouble tracking down the wiring for the compressor clutch. I disconnected the two harnesses in the first photo, but this cut power to the condenser fan. Is there a harness for the compressor? The only wiring I could find appears bolted to the top of the compressor (I see the red wire on the bottom right of the second photo, but I'm not sure where it goes). What am I missing? I'd like to make sure that there is continuity to the compressor clutch.

Also, the compressor clutch/condenser fan fuse now blows immediately when I try to turn on the AC. Is this still consistent with a bad compressor clutch? Could it be a bad compressor? When I try turning the clutch plate with my fingers when the car is off, I can turn the plate. I ordered a new compressor clutch and would like to install it on Sunday, but I'd like to make sure I'm not missing anything obvious.

tony_2018

follow that red wire

avinoam83

Should I be able to find the harness from the top of the car?

avinoam83

I do have voltage at the harness leading to the compressor.

tony_2018

unplug the compressor harness, start car and start ac. Does it still blow a fuse?

avinoam83

No. I'm in the middle of swapping clutch, just trying to get plate and pulley off.

tony_2018

K.

avinoam83

I believe armature plate is supposed to come off when I remove center bolt, mine in stuck.

tony_2018

try using a flathead to pry it off?

avinoam83

Did that. Now I have a stubborn pulley. Safe to use flathead for that? Borrowed a tool from Advance Auto but I don't think it's the right one.

tony_2018

spray some lub on there?

avinoam83

I think I'm supposed to use a puller. I sent my dad to the auto parts store with a picture of the puller and the clerk sent him back with something completely different. Ugh.

tony_2018

3 jaw puller will do. Problem is you might have to lower the compressor to use it as the frame of the car will be in your way. Use your hydraulic jack as a stand and lower it enough to fit and turn the 3 jaw puller but not enough that you kink the ac lines connected to it.

avinoam83

I disconnected the four bolts for the compressor so I think I have enough space to work ( I think?). I did forget to remove a snap ring. Maybe that's why it isn't coming off.