Working on a friend's 1994 Honda Civic DX. Attemtping to repair A/C.

A/C 20 amp fuse blows when A/C is turned on. Isolated condensor fan and it runs fine. Then connected 12 volts to compressor sensor & clutch and it draws way too much current. I am assuming the sensor on the compressor is OK and if that assumption is correct, the clutch is shorted.

System is holding pressure -- 140 pounds I believe. Can I replace just the clutch without releasing refrigerant or should I replace the compressor-clutch assembly? Appears there is no way to get to clutch without removing the compressor.

Thank you for your time and advice.

Frank

 

You can work on the clutch with the refrigerant still charged. Raise the front of the car and remove the plastic splash panel on the bottom front. Take the belt loose, unbolt the compressor from the engine and lower it down some, with the refrigerant lines still attached.

Take the shaft nut off and slide off the clutch plate, being careful not to lose the shim washers on the shaft. Take the snap ring off and pull the pulley/bearing assembly with a standard gear puller. Take another snap ring off and pull the coil.

 

Thanks for the advice!

I'll do that way. That will avoid the evacutation/charge processes.

It seems that some of the turns of the field coil are shorted. However, when I isolated the field coil from the rest of the electrical components, the thermal protector was actually still in the circuit. I suppose it could be shorted, but I assume that is very unlikely. Do you have an opinion in that regard?

Can the thermal protector that is mounted and silicon sealed into the compressor housing be removed without discharging the system?

Perhaps an easier way around that issue would be to disconnect the lead to the field coil from the thermal protector and then check the field coil by itself. Can the protector and the field coil leads be disconnected from each other?

Again thanks for your time and advice.

Frank

 

The thermal protector is glued into a blind hole in the compressor case. However it is rarely a problem. I would not try to remove it unless it is certainly bad. So cut the wire and you can test the coil separate and/or confirm the protector is shorted to ground. On mine there was a connector in the wire, but it was under the metal clip that holds the wires down. (Also make sure the wire didn't come up and get cut in the pulley and shorted there, that may be the only problem).

A new coil will not come with a protector; you might have to cut and splice the wire anyway.

 

OK. Sounds fine. I ordered the coil today. It is to be available on Friday.

My plan is to drop the compressor and work on it there as you explained. That process will save a lot of money.

The wires that go under the pulley appear to be fine. There appears to be clearance between them and the pulley.

I'll check to see if there is a connector on the protector. And I really don't think it is bad because when I applied power to the coil through the protector, the clutch plate actually picked up during the same instant the fuse blew. So I think the coil has some shorted turns, but enough turns remain intact to create the magnetism required.

Am I correct in assuming that the nut will be strong enough to pull the pulley back onto the shaft after the coil is replaced?

Also, the manual states that a "special tool" is needed to remove the pressure plate from the shaft. Per your advice, the plate slides off. Perhaps it slides off with some uniform prying between the plate and pulley... or does it actually just slide off the shaft?

Thank you for your patience with all these questions.

Frank

 

On the Sanden TRS090 compressor, the plate just slides off as it is splined on. When reinstalling, note that the splines are special so it only fits in one clock position (as the clutch plate is eccentric to balance the internal parts of the compressor). I don't know about the Mitsuba or whatever the other compressor that may be fitted to some cars.

The only thing you may have to use a little force on a Sanden is putting the coil and bearing on and off their bosses. Don't try to use the nut for that. Tapping gently and evenly with a rubber hammer should do it.

 

OK. Thanks for the advice... Not sure what brand the compressor is -- car isn't here right now. Sounds as though the nut is not strong enough to pull it on.

I'll let you know how it goes.

Frank

 

OK... got the new coil in and the A/C now works... pretty much. At first, the compressor clutch was slipping on the pulley. It would cool but the slippage was not good. The high pressure side was very hot. We let some r-134a out, thinking there was too much in the system causing the compression to be too high. After letting it out a few times, it seems the clutch quit slipping. The pressure on the low side would get as low as 25 pounds, which seemed to border on being too low. We didn't have a gauge for the high side. Temperature here in Kansas was just below 100 degrees and Humid.

Only problem(?) seems to be that the compressor cycled on and off too often. There were no bubbles in the sight glass. When the engine was not running, the system pressure measures right at 100 pounds (measured on the low side).

The problem with the old coil was that there were a bunch of broken wires that were most likely shorting to the pulley. So for some reason, it appears that coil got hot - burned off the enamel and melted the resin(?) seal. Perhaps from over charging r134a?

I am hoping these symtoms may tell you something... I am thinking the pressure may still be too high because as we let more freon out, the load on the engine seemed to lessen and the clutch quit slipping and there were still no air bubbles in sight glass. Only problem is compressor seems to cycle too much now.

Any advice?

Thank you for your time and expertise.

Frank

 

You should remove all the refrigerant and put back the proper amount by weight. Have a shop do it if you don't have equipment. If people have been adding stuff to this system, there may be too much oil as well. Besides excess refrigerant, oil, or air in the system, another common cause of excessive high side pressure is failure of the condenser fan.

The compressor should be quite easy to turn by hand (turning only the front plate with the engine off). If it is stiff, it is probably about to seize up on you.

 

Thank you for the continued advice.

I did check the condenser fan and it operates OK.

I don't have a gauge that fits the r134a high side, so we will take it in to have that checked.

When the system is evacuated, does that process remove the oil? I was wondering whether there could be too much oil in the system and how critical that is to the system's operation.

It seems the compressor does turn pretty easily by hand. Of course, I'm not a good judge when it comes to "turning easily". Also, it seemed that the compressor clutch wouldn't slip when first turned on, but, after say... 20 to 30 seconds, it would slip. So, turning by hand, with the engine off, might not be the right test. However, after removing some Freon, it quit slipping, but continued to cycle too frequently.

We'll take it in today to have it looked at.

One other question I have... If the compressor bearings and seal about the shaft are good and the proper amount of oil and refrigerant is in the system, is there something else that can commonly fail in a compressor? I mean, are we not out of the woods yet, considering it does cool and seems to operate "pretty" well?

Thanks again for your time and patience.

Frank