ac help for beginner

[tucknroll]

hey guys, when I bought my 69 charger, the guy told me he didn't think the ac worked and it was unplugged so I never thought about fixing it because the heat don't really bother me. well, today (2 years later) I plugged it up and turned it on just to see what would happen and it blows air. just not too cold. can someone talk me through charging it up to see if it blows cold? I have no idea where to even begin! thanks

[green69rt]

After two years, you may just want to go to an AC guy you trust and let him run leak tests, etc.  That way you'll know what your starting conditions are.  A simple diagnostic shouldn't cost much.


If you want to learn how to work on AC systems you'll need to get a set of gauges, can't do much without them.

[Dino]

If it's still running R12 you may have difficulty finding a shop that will touch it, but it won't hurt to ask around.  What exactly did you plug to get it running?

[Pete in NH]

Hi,

Okay, beginners A/C. These cars left the factory with R12 refrigerant which was phased out in the early to mid 90's in favor of the newer, more environmentally friendly R-134A. Many older systems were converted to R-134A but, not all were, some still retain their original R-12.

So, the first question is what is in yours? Converted systems were supposed to be labeled as such with type of Refrigerant , quantity and oil type. Unfortunately for future owners this labeling is very often not done but, look around under the hood you may get lucky. The original factory R-12 tag will be mounted on the compressor if it is the original RV-2 type. Another way to tell a conversion is to look for R-134A adaptors on the compressor service ports. Also, a really good A/C service shop will have a refrigerant identifier and can hook it up and tell you. If it is still R-12 as Dino mentioned almost no one wants to deal with it today and will want to convert it to R-134A.

Post a picture of the compressor and its service ports and that might tell me what you have there.

[tucknroll]

It reads r12 refrigerate 

[tucknroll]

That wire is what I plugged up also

[Dino]

Okay so that was the power feed to the compressor.  These systems actually work really well so you can either try to find someone who can recharge it with R12, or get licensed to do it yourself.  Or you can convert it to R134a which means evacuating the system, removing the epr valve and installing a thermostatic switch, replace the rubber hoses with barrier hoses and charge it up!  The compressor would need to be flushed as well and the drier replaced but that's cheap and easy.

The barrier hoses you can get from classic air I think but an a/c shop can just make them for you.  Just give them the old hoses and they can duplicate them.  Nothing to it.  Some people reuse the old hoses when upgrading but I really can't recommend that. 

There may be more to it, my brain is working overtime on too many projects...Pete will set me straight though.   

For the record, I vacuumed my old system and installed a modern Sanden compressor.  All I kept was the stock evaporator and the hard line running from drier to condensor and this sucker will freeze me out of my car running R134a. 

[Pete in NH]

Okay, thanks for the picture, pictures are always very helpful. The service ports look like the original R-12 ports and the tag on the RV-2 will of course mention R-12. One would hope if it was converted to R-134A someone would have removed that tag, but, of course you never know.

You're missing a belt on the compressor drive, it should be a dual belt set up. That's okay for just driving the alternator but the single belt won't deal well with the A/C load as well. The easiest thing to do would be keep it R-12. Either find a local shop that still deals with it or look on line about getting your 609 certification so you can buy R-12. There is still a lot of real R-12 offered on EBay for around $30 to 40 a can. These systems leak a little by design so over the years they loose charge. The RV-2 shaft seals leak small amounts of refrigerant. Forty years ago this was acceptable since R-12 was very cheap and if you had to add a can every 5 or 6 years that was okay.

If you want to convert to R-134A, Dino covered the high points. I would add you need to change the oil in the compressor to a R-134A compatible type, you can not leave the old mineral oil in there. I like to use an ester based oil then you can go either R12 or R-134A. My preference is BVA-100 Ester Glo with built in U/V dye. I would rebuild the hoses either way 45 year old hoses under pressure is not a good thing. Classic Air can rebuild them but, they are very expensive. I'm sure you could find a local shop to do it for far less. Unlike later systems, these systems seem to take quite well to R-134A conversion. They were so over designed they have plenty of condenser and evaporator capacity to deal with the less efficient R-134A.

If when you turn the A/C on the inner hub of the compressor turns as well as the outer clutch pulley there is still enough refrigerant in the system to keep the low pressure cut off switch satisfied. If so, look in the sight glass on the top of the receiver/dryer, the can like thing on the passenger side fender. You will see what looks like foam. If the system has a full charge of R-12 that sight glass would be clear liquid.

[John_Kunkel]

My advice...resist all advice that involves changing the refrigerant type, stay with the R-12. Replace the compressor seal and the dryer and have the hoses rebuilt using barrier hose then charge the system with R-12.

[tucknroll]

Man YOU GUYS really know your stuff . I'll tinker with it this week and post what's up when I get going.

[tucknroll]

im trying to figure out where the belt missing from the compressor goes. I turn it on for just a few seconds and it really pulls the motor down. I cant seem to work it out looking for the right places for it to go. is there a diagram for this? thanks

[Pete in NH]

The belts both follow the same path, crankshaft pulley, alternator, A/C compressor. The alternator acts as the adjustable idler to adjust belt tension. From your photo, The belt is on the outer groove on the compressor but, on the inner groove on the alternator. The upper radiator hose is blocking a full view of the alternator, but if it really is that way something is wrong. It may be that the alternator is too far forward and not mounted correctly.

My 383 picks up the A/C very easily. The A/C should not bog down the engine. Try turning the bolt in the center of the clutch on the compressor with a socket and breaker bar in a clock wise direction. It should turn fairly easily and you should get some resistance as a piston in the compressor hits a compression stroke. If the compressor is hard to turn or doesn't turn it is likely in trouble internally and will need to be replaced. That may be why the wire was disconnected. About the only thing that will ruin an RV-2 is lack of oil.

I think at this point you really have an A/C system in unknown condition and it's likely to need more than just adding refrigerant.

[tucknroll]

well, I was wrong. the air I felt was just the fan. the compressor comes on but the clutch only closes but wont engage. should I buy a new clutch only since the compressor starts. also, do I have to take both off to put the new clutch in? thanks

[John_Kunkel]

the compressor comes on but the clutch only closes but wont engage.

Huh? Are you saying that you can hear/see the clutch engage but the compressor doesn't turn?

If so, put a 1/2" socket wrench in the bolt at the front of the compressor clutch and try (gently) to turn it clockwise; if it won't turn, the compressor is seized and a new clutch won't help but if it turns, a new clutch might help. BTW, the fact that the clutch engages means there is still pressure in the system and a simple top off of the existing refrigerant is all the system needs.

[tucknroll]

I got bad news. we charged the compressor with r12 and the compressor seems to be locked up.the clutch got really hot. is there a place to add oil to it? do yall recommend rebuilding it or a new one? the good news is my brother found the motherload of r12.

[Pete in NH]

You might have saved yourself quite a bit of trouble by following John's and my suggestion to try turning over the inner compressor clutch hub with a socket  and breaker bar. The compressor is very likely seized up from lack of oil and is now basically scrap metal. You're going to have to replace it with a rebuilt RV-2. Rebuilding the compressor you have is not really an easy project because very likely all the internal parts are now scrap and finding new parts is difficult these days.

If there is still R-12 in the system you're going to have to get that recovered and out. While replacing the compressor you should also replace the receiver/dryer unit. If you are staying with R-12 you will need to make sure the new compressor is filled with 10 OZ of 525 A/C mineral oil.

Also, was there still R-12 in the system before you added more? If you added R-12 to an empty system without pulling a vacuum on it you were trying to compress air which could lock up the compressor.