Fragmare

So now that I've got the car running the way I want, it's time to finally fix the A/C system. The compressor was getting no clutch action. I had the entire system deep vacuumed so it's empty of all refrigerant/oil. Then I removed the compressor and found a break in the main power wire. I braided, soldered and insulated that, so that's now fixed. While I had the the compressor out, I decided I'd take the thing the apart and inspect it a bit more closely and give it a good cleaning too. After taking the armature plate and pulley off, I noticed something funny looking on the top of the field coil. It almost looks like there's a small "pit" in the resin coating on the coil itself (see pic attached). That half of the coil also looks darker compared to the other side. Did the A/C compressor's field coil get fried at some point or is this simply an imperfection in the resin coating? I tried testing the resistance of the field coil and didn't get any readings, but my multimeter is pretty cheap and inaccurate and I'm not even quite sure if I'm making contact with the right wire... the service manual's diagram is a little ambiguous. Is this field coil blown? For testing field coil resistance, do I test the little black wire that's held onto the compressor by a 8mm bolt?

ezone

There must be 2 places to attach your ohm meter: One is the power wire, the other is the ground (the eyelet connector that was bolted to the compressor).

A clutch coil should have somewhere around 2 to 6 ohms or so of resistance (general rule of thumb, can vary with temperature).

Make sure to check the clutch coil separately from the thermal protector. Either one can be faulty, the result is the same (no engagement/open circuit).


------------------------------------------------

It doesn't have to be ugly to be bad.

Is that blemish in the pic a hole? Does it go all the way to the wire (coil)?
If the coil has no continuity, that could be where the bad spot is, but really it doesn't mean a whole lot unless it has exposed the wires inside.

If it was really burned from overheating, you wouldn't need to ask.
You would be saying "DAMN!"
The whole thing would be all melty.

HTH

Fragmare

Okay, I finally got some readings I can make sense out of after measuring at the recently resoldered main power wire (+) and the eyelet (-). Here are the ohm results I got:

Base reading: ~0.6 ohms when touching both test leads together on the meter (it should be 0.0, but my meter sucks).

Field coil reading: ~3.4 ohms at 74 degrees (though, given the base reading of 0.6, I'm thinking is really closer to 2.8 ohms)

The service manual states the field coil resistance should be 2.8 (+/- .15) ohm @ 68 degrees.

So I'm guessing the coil resistance is right where it should be?

--------------------------------------

That blemish is only about 1/8 in. deep and doesn't appear to go down to the wires. It just looked concerning because that whole side of the coil is black and there are what looks like bubbles suspended in the resin. The other side is semi-transparent, with no bubbles. If the coil resistance readings are okay, should I be too worried about this or could it just be from how they poured the resin?

ezone

Sounds like your coil is right in spec. (I guessed at those numbers earlier)
Did you check the thermal protector? Should have continuity.

0.6 ohm: Could just be the leads on your meter too. They really should read zero ohms when touching each other.

Don't worry about the bubbles in the resin, it's from the pour and curing. I'd run it.


HTH

Fragmare

I'm working on it. I stripped out the tiny little screw that holds the connector's clamp in place. It's out there soaking in AeroKroil right now. Here in a little while I'll go hit it with a drill and extractor bit. No retreat!

Yea, it's definitely off. The LED display is wonky too. It's a $7 Harbor Freight junker, but I think I'm going to take it back and get the higher quality one they sell.

Phew, glad to hear that. Had me concerned.

One other thing... I don't have a shop press, so when I put the pulley back on, I sat the compressor on a folded up towel, stuck a 32mm axle nut socket into the center of the pulley (a perfect fit btw) and whacked the socket with a plastic mallet a few times until the pulley was fully on there. I then reinstalled the armature, measured the amature pulley clearance, and it was too tight. Took the thing off, found a small washer in my spare washer can (from an old fuel filter, iirc) and used that in addition to the factory shim, put the armature back and it was back to within spec (it's .015 in. service manual calls for .014 - .026 in). Then I spun the pulley and listened and it seemed to spin okay and wasn't grinding. I know it's not ideal, but do you think that'll ruin the whole thing?

ezone

whacked the socket with a plastic mallet a few times until the pulley was fully on there.

I do similar, depends on what is handy.
2x4 and a dead blow hammer is convenient sometimes.

I sure wouldn't use a hydraulic press to install the pulley though.




I then reinstalled the armature, measured the amature pulley clearance, and it was too tight.

Lost a shim? I hate when that happens.


Took the thing off, found a small washer in my spare washer can (from an old fuel filter, iirc) and used that in addition to the factory shim, put the armature back and it was back to within spec (it's .015 in. service manual calls for .014 - .026 in). Then I spun the pulley and listened and it seemed to spin okay and wasn't grinding. I know it's not ideal, but do you think that'll ruin the whole thing?

Sounds like a workable solution to me.

HTH

Fragmare

Okay, the thermal protector checks out okay too. I also took the middle bolts for the compressor off and checked out the bearings inside out and they look good. I think I'm looking at a good compressor here. Next day off I have I'm going to replace the filter/drier and put the fixed compressor in along with a new belt and go have a deep vacuum done on the system. Then I'm going to put some Ester oil (i think the proper amount is around 6 oz., I'll double check the manual though) in there (it's a retrofitted R12 system) and the proper charge of R-134a (21-23 oz., iirc). Then see if the thing blows cold!

ezone

Here is some snippets of info from the official Honda AC retrofit guide:

"120ml of PAG oil is added to the system"
on top of whatever oil was left in the system after removing the R-12.
So PAG oil is used with Hondas R134a conversion according to this, not Ester, Mineral, or POE. But any oil could be in it, there isn't really any good way to tell what is in it now. Depends on whoever did the original conversion.

"Determine the amount of R-134a refrigerant needed to charge the system by subtracting 50 ml (1-2/3 oz) from the system’s R-12 capacity."
There should be a sticker with the original R-12 capacity, and/or a sticker with the new R134a capacity from when the conversion was done. That sticker should also say what oil was used when the conversion was done.


Of course, anyone could have done the conversion using any of several kits and/or methods available. Hondas kit and methods may not apply.

YMMV, HTH

Fragmare

Hey, that's good info about the amount of oil and R-134a to add! Thanks, I was wondering about the proper amounts (I knew they were different).

Oh, and I performed the retrofit myself. By "perform", I mean I simply installed new valves on top of the old high/low side ones. It literally took about 1 minute. The system is also empty or nearly empty. I had all the R-12 and mineral oil evacuated a few weeks ago in preparation for removing the compressor/drier. There was some place around here running a special for a free A/C diagnostic and vacuum, so I jumped at it. Why not? It was free!

So Honda recommends using PAG in retrofitted systems, huh? I've read something to the effect that any residual mineral oil or R-12 will break down the PAG and diminish its lubricating qualities drastically. I've also heard that Ester oil doesn't have the same issue of breaking down when in contact with any residual mineral oil left in the system. I'm guessing that's why they advertise it as being for retrofitted systems on the Ester oil can. Is there any truth to that?

I've also noticed that both Ester and PAG oil come in three different flavors; high, medium and low viscosity. Which one should I be getting or does it really even matter?

I've read somewhere that most A/C system parts manufacturers recommend that when adding new oil to the system, that you add half of it to the compressor and the other half to the drier... or better yet, the proper amount for each system component as listed in the service manual. I'd love to do it that way (as opposed to just charging the system with oil + 134a), so no part of the A/C system would be lubricant-starved upon recharge, but I'd need to open the system to air in order to do that. Then I'd have to vacuum the system which would remove the oil I just put in. Is there any solution to that little catch-22 or should I just vacuum it and let rip with an oil charge?

ezone

A problem with your assumption: The oil in the system is NOT removed when under a vacuum. Only a small amount, whatever is carried in a vapor state with the freon, is removed. The rest of the oil just lays in the bottom areas of the system, gravity in effect.
(A system might hold 8oz, but maybe 0.5oz comes out with a recover and evacuate.)

The AC oil we use right now is SP-10. Not sure on what was used in a conversion kit though.

Oil takes up space in the system, thereby reducing available capacity for the system to hold freon. It is easy to get too much oil in a system, and then it will act like it has too much freon when charged according to the labeled weight.

The PAG notes, that's what came up under retrofitting when I put your cars info into the system. The oil normally used with and leftover from the R-12 will now lay in the low areas of the system and sit there (or move along slowly), while the PAG oil is supposed to vaporize easily when the R134a is moving, and get carried along with the flow of freon throughout the system. (That's what I remember reading before, anyway.)

Adding oil: When I do a complete system (or an OEM compressor), the oil for the system comes already inside the compressor (OEM), thats the entire system capacity of oil. The compressor gets bolted on, and the system is run normally. (If only the compressor is replaced, there is measuring and removing oil to be done.)

The oil WILL get distributed as the system operates. So it really doesn't mater WHERE the oil is put in, it will eventually get circulated to all parts of the system.


Lunch is over.
HTH

Fragmare

Ahhh, I see now! When the system is evacuated, the oil is not removed to any significant degree... That makes so much more sense now.

Well, since I let the compressor drain almost completely before capping it and I'm getting a new (I'm guessing bone-dry) filter-drier, do you think I should add a little extra oil beyond what is called for in the retrofit?

Whatever amount I add, I think I'll get the screw-top can of oil and put the service manual specified amount in the drier and the rest in the compressor. Then install them both, tighten up all the bolts, and go get another vacuum done before I charge the system. Sound like a good plan of action?

BTW, I'm not finding drier removal procedures in the manual, but it looks like you remove the turning light, headlight, wiper fluid tank, and possibly the bumper to get at it. Does that sound about right?

ezone

Umm, Try spending a little at Sears for something that MIGHT be a tad bit more reliable instead.




Since you didn't add ANY oil when you converted it before, I would say to add whatever amount of oil would have been in the official retrofit kit and call it good (because it should have been enough for a complete system), and continue with charging amounts as per the conversion guidelines....... but I have no clue how much oil that would have been.....It has been years since I have done a conversion. I really want to say it was a 4oz can, but I honestly can't remember. And I can't find that info on the Honda site ATM.


Do you realize just how often (rarely) I see a car as old as yours?

Yes.....Replace the O ring on every connection you touch though. Use the proper O rings for use with R134a, usually they are green but some (factory parts) are black. Many parts stores will have a huge selection available in a box, pick out what you need. (R12 and R134a have different needs as far as seals go.)


Remove bolts, remove part. Like a Chilton manual. Duh.

Looks like it will have a bolt for each AC pipe, and a clamp assembly that can be unbolted and lifted out or undo one single bolt that is holding the clamp around the bottle.
Whichever is easier.
IDK, I can't see what you are dealing with.

Replace the O rings, and lube them with compressor oil (I use silicone spray lube for the O rings sometimes, it's handy.) Install the pipes gently so the O rings don't get cut, then bolt them in. Then mount the bottle in its bracket and tighten.




Confused?
HTH

Fragmare

Already done. I got a much better and more reliable multimeter that actually reads 0 when you need it to. The compressor still checks out to spec as well.

Thanks, I'll try to see what info I can dig up on it. I went out tonight and got the oil (I spent an extra buck for the kind with UV dye in it, in case the thing springs a leak later), drier, green o-rings, and 24 oz of 134a. The car's pulled in the garage and here in a bit it's time to get that old drier out.

Oh, I can imagine. I really love the thing, so I'm trying to restore it. The A/C just happens to be the next thing on the to-do list.

Sounds good, I'll get on all this later tonight

Nah, I'm with ya. I've been planning this for the last few weeks, I just needed to get the time and parts and a little input from helpful experts like yourself. Thanks!

Fragmare

Well I installed the new drier last night (what a pain in the ***!), installed the fixed compressor, put 4 oz. (1/2 a cup) of oil in the compressor and 1/3 oz (2 teaspoons) of oil in the drier, put new green neoprene o-rings on the compressor/drier connections, torqued everything down to spec. Then I went and had the system vacuumed out (the shop down at the corner only charged me $10 bucks for a deep vac... nice!) and put in about 21 oz. of 134a. I noticed right away I was getting proper clutch action. Then I got in the car and took it around the block... it blows COLD after it gets going! Hope it doesn't spring a leak... though if it does, I used used the UV dye oil so it'll be easier to tell where it's coming from, I suppose.

Thanks a ton, ezone! This will be great tomorrow when it's 98 and I'm taking the kids out to the beach.