[OVERULD]

I had asked a question over in my thread on Gauge Cluster Question regarding what a loose wire in my engine bay went to.

Here is the question, with my photo, and some responses from NJSteve and 77Canamman

Originally Posted by OVERULD

And while we are speaking of random wires...what the heck is this connection and where is/what does the little button looking thing that is stuck through the oil dip-stick handle supposed to go/do?



Thanks,
BJ

Originally Posted by njsteve

That button thing is the superheat switch connector that connects to the superheat switch terminal on the rear of the a/c compressor. The black plastic three wire connector is the a/c compressor fuse. If the superheat switch reads a loss in freon pressure, it grounds out internally and blows that black plastic rectangular fuse before the compressor can blow itself up. That melted hole in the middle of the fuse indicates it is blown. Does the a/c work?

Originally Posted by njsteve

Don't replace the fuse and reconnect that connector until you refill the A/C system or it will just burn out your new fuse.

Attached is a shot of the rear of the compressor with the superheat terminal that, that black "button" connector should be connected to.

Here's a link to the thermal limiter fuse as it is referred to.

https://www.rockauto.com/en/partsearch/?partnum=tls1

Originally Posted by 77 Canamman

Versions of the Delco 15-2109 6551258/GM 3909030 thermal limiter:

[OVERULD]

So - to answer a few questions

Steve, no the AC does not work, now I know why.

Here are a few photos of my compressor, including the back of it. I don't think it has the button connection point like shown in your photo.







Mike (HFR) asked early in my thread 74 455 Project Begins, what the numbers were on the compressor Code No. stamp. They are 012892

Given all the above, what is my next step? I know that a previous owner had it converted to R134 and I have some receipts in the binder on some of that AC work. It was known to have a leak and that explains why the fuse is blown. Before I spend a bunch of time and money on chasing the problem, what do you think I should do first?


Thanks,
BJ

[Held for Ransom]

That is a '69 compressor. So, if it was me, the first thing to do would be to find a '74 compressor.

Here are some '74 pictures of the wiring.

[njsteve]

Yup, wrong compressor. And they added that low pressure switch and some type of brass valve to the rear fitting on the compressor, and some extra white wires (in your last photo of the label). Get us a better photo of the wires and what they are connected to as highlighted in the photo.

Classic Auto Air is a good place for parts. I bought this hose from them for my Gramma Car - it's the same one piece assembly that your car takes. It uses the modern multi layer, barrier, rubber hose that can handle both R12 and R134 (R134 will seep through the original factory hoses). Replace all the O-rings with modern green colored ones also made to handle both refrigerants. I would also get a compressor from them or have them rebuild yours and add the correct back with the superheat switch. They can also rebuild the VIR assembly (the cylindrical contraption hanging off the evaporator case).

I'd then fill it with R12. Mine runs at 36 degrees with R12 and would barely break 50 degrees when it had modern refrigerant in it.

https://originalair.com/74-76-firebi...remote-muffler

.

[DOC]

Originally Posted by OVERULD

So - to answer a few questions

Steve, no the AC does not work, now I know why.

Here are a few photos of my compressor, including the back of it. I don't think it has the button connection point like shown in your photo.







Mike (HFR) asked early in my thread 74 455 Project Begins, what the numbers were on the compressor Code No. stamp. They are 012892

Given all the above, what is my next step? I know that a previous owner had it converted to R134 and I have some receipts in the binder on some of that AC work. It was known to have a leak and that explains why the fuse is blown. Before I spend a bunch of time and money on chasing the problem, what do you think I should do first?


Thanks,
BJ

Take the wire that would attach to the superheat switch and ground it. See if anything works then.

[77 Canamman]

Originally Posted by njsteve

Yup, wrong compressor. And they added that low pressure switch and some type of brass valve to the rear fitting on the compressor, and some extra white wires (in your last photo of the label). Get us a better photo of the wires and what they are connected to as highlighted in the photo.

Classic Auto Air is a good place for parts. I bought this hose from them for my Gramma Car - it's the same one piece assembly that your car takes. It uses the modern multi layer, barrier, rubber hose that can handle both R12 and R134 (R134 will seep through the original factory hoses). Replace all the O-rings with modern green colored ones also made to handle both refrigerants. I would also get a compressor from them or have them rebuild yours and add the correct back with the superheat switch. They can also rebuild the VIR assembly (the cylindrical contraption hanging off the evaporator case).

I'd then fill it with R12. Mine runs at 36 degrees with R12 and would barely break 50 degrees when it had modern refrigerant in it.

https://originalair.com/74-76-firebi...remote-muffler

.

X100000000

Main thing is to find a compressor with the Superheat switch, and correct pulley diameter/depth. Be aware that some A6 compressors had metric threads on the mounting boss.

[OVERULD]

You guys are an awesome resource - thanks!

Got a busy week ahead, so it may be a while before I report back on this.


BJ

[njsteve]

Originally Posted by DOC

Take the wire that would attach to the superheat switch and ground it. See if anything works then.

Nothing will happen because the fuse is blown already.

[Pepi]

Originally Posted by DOC

Take the wire that would attach to the superheat switch and ground it. See if anything works then.

No, don't do that. IF the thermal limiter isn't blown, you will blow it. You can run these compressors without the super heat switch hooked up. I did on mine for many years, not by my choice. Someone else changed the compressor and it didn't have the super heat switch, so they cut the end off of it. When the evaporator went, the oil and R12 leaked out and seized up the compressor. If the superheat switch would have been hooked up, it would have only kept the compressor from running and it would not have seized.

I think it is B & C, that if you jumper, it will allow the compressor to cycle. You should be able to do that without the engine running and hear the clutch magnet click. Could be a bad clutch.

Karl

[Aus78Formula]

I don't know why people have so many dramas getting refrigerants other than R-12 to be cold, you only have to use correct settings. Anything can freeze up the system but if you haven't set it that way it won't, you can't blame the refrigerant for what you haven't asked it to do. Of course, there's ways to be more efficient using different refrigerants, but that's extra again, and not something comparable with 70's factory setups.

[77 Canamman]

Originally Posted by Aus78Formula

I don't know why people have so many dramas getting refrigerants other than R-12 to be cold, you only have to use correct settings. Anything can freeze up the system but if you haven't set it that way it won't, you can't blame the refrigerant for what you haven't asked it to do. Of course, there's ways to be more efficient using different refrigerants, but that's extra again, and not something comparable with 70's factory setups.

Propane works better than R12, but you can run that in your car, not mine...

R134 is a more inefficient refrigerant than R12. With the condenser design standard in the 1970's Pontiacs, you will never see the vent temps as low as they should be. The best I got out of one of my cars with R134 was 46, which is cool, not cold...

[OVERULD]

Originally Posted by njsteve

Get us a better photo of the wires and what they are connected to as highlighted in the photo.

Steve, if you look at the first photo in my original post above, you can see the ends of the two white wires coming off the electrical connector at the brass fttting. They both appear to connect to green wires inside of a black sleeve. One seems to go to the superheat fuse, and the other goes to the connection for the clutch on the front of the compressor.

Is it possible that is providing the same function?

BJ

[njsteve]

I was thinking that as well, but they are using a later model switch on some kind of brass adapter that I have not seen before. I'd get rid of that contraption, reconnect the green wire back together and have the system vacuumed out to see if it leaks. Then go from there. Or just replace the entire hose assembly and the compressor with a correct one and hunt down some R12.

[Pepi]

Does it have a POA Valve? They make a POA Valve eliminator which has a new pressure switch. Maybe those wires are spliced in and go to that.

[njsteve]

No. it's a 74 so it has a VIR not a POA.

[77 Canamman]

A VIR Conversion kit is also available.



http://www.ebay.com/itm/360439750124...%3AMEBIDX%3AIT

[njsteve]

Why would you want to update to something that doesn't look anything near stock?

Classic Auto Air can rebuild your old VIR. Something else to think about since the system probably has no refrigerant in it any more and has been open to outside atmosphere. The VIR canister took the place of the POA valve and the receiver/drier which had the desiccant material in it to absorb moisture. It combined them into one unit for 1974 to 1976. It says on their webiste that the VI system is not recommended for R134. So that means stay with R12 - you'll be much colder (and happier)

https://originalair.com/74-76-pontiac-vir-rebuilt

Here's what yours should look like when it's done. My car has the Classic Auto Air hose and is running the original VIR system with R12. It is using one of the recently remanufactured A12 compressors which as someone previously mentioned, use metric mounting bolts to attach the compressor to the original brackets. (In looking at the photos you posted of your current compressor, it looks like it already has metric hardware on the rear lower mounting brackets).

[77 Canamman]

For a driver, I would not hesitate to convert it to the later controlled cycling system, as used on the 1977-up cars. I have had a few issues with stuck valves with the VIR and POA type system.

For an authentic resto, there is no other option really.

[Held for Ransom]

The good news is after getting the rebuilt unit, you can place a repro decal on it for a more authentic look. PN 1131058.

[Pepi]

Originally Posted by njsteve

No. it's a 74 so it has a VIR not a POA.

I thought about that after I posted and on m way to work. I knew something didn't seem right when I was typing it this morning.