Again, A6 compressor backplate date codes?

[Domenic T.]

I went thru the archives and here is the question again!!
I did some research on some backplates I just purchased. Some have the M/DD/Y under and between both ports on the back plate and some have the M/DD/Y under the right port. I punched up calanders of the 60's & 70's to see if the dates came up on weekends or holidays.
I first looked at the codes on the 1960's calenders and some were Saturday & Sunday dates. So I looked at the same backplate codes using the 1970's calander and again, some were made Saturday & sunday.
All the backplates checked do not have the thermal switch on them that came out on the1970's cars.
My first guess was that the M/DD/Y under and between both ports were from the 60's and the M/DD/Y under the right port was from the 70's. If that is true then backplates were made on Saturday & Sunday in the 60's and 70's!
What was the last year of the A6 compressors? Did all the later compressors have the thermal switch on the back or did some of the later cars not use the thermal switch?
Not much known about this and I see lots of cars with A/C that have the wrong date codes and even thermal switches on them! Do the judges look at the compressors when judging a car?

DOM

[Edward J.]

Re: Again, A6 compressor backplate date codes?

Dom, A6 compressors seem to look much the same without the pulleys installed( as you know), so I know that the dates on the rear of most of the compressors are blocked by the hose and manifold assy. so the important things Looked at would be the pulley configuration and the labels. other wise, I am not sure there is much else that tells them apart. As you say the switch on the back was another way, but some of the plates with the switches on the back could be blocked off if not used, and most judges may not even have a clue if all the other componets look correct, A correct label is the most important part of judging the compressor.

[Domenic T.]

Re: Again, A6 compressor backplate date codes?

Ed,
I was waiting for your opinion, your right on. Not much other than the pulleys and repo foil tags. The only other thing I would say is that GM may have had the back plates made by someone else or they worked weekends.
Then we have the metal tags when they first came out. One of the clues is the amount of R-12 on the tag.
Thanks, DOM

[Terry M.]

Re: Again, A6 compressor backplate date codes?

I went thru the archives and here is the question again!!
I did some research on some backplates I just purchased. Some have the M/DD/Y under and between both ports on the back plate and some have the M/DD/Y under the right port. I punched up calanders of the 60's & 70's to see if the dates came up on weekends or holidays.
I first looked at the codes on the 1960's calenders and some were Saturday & Sunday dates. So I looked at the same backplate codes using the 1970's calander and again, some were made Saturday & sunday.
All the backplates checked do not have the thermal switch on them that came out on the1970's cars.
My first guess was that the M/DD/Y under and between both ports were from the 60's and the M/DD/Y under the right port was from the 70's. If that is true then backplates were made on Saturday & Sunday in the 60's and 70's!
What was the last year of the A6 compressors? Did all the later compressors have the thermal switch on the back or did some of the later cars not use the thermal switch?
Not much known about this and I see lots of cars with A/C that have the wrong date codes and even thermal switches on them! Do the judges look at the compressors when judging a car?

DOM

I am not sure if you are asking for the last use of A6 on Corvette, or last use on any GM vehicle.
I once owned a 1976 Suburban with an A6 that cooled quite well through both front and rear AC units. That's all I know about the use of A6.

[Domenic T.]

Re: Again, A6 compressor backplate date codes?

Terry,
That's part of it but the real question is the decade of the code on the backplate. I thought the centered date codes were of the 60's, and the right side date codes of the 70's. When I check the centered date codes to see if they were built on weekends I find them to be made on weekends. This is using the 60's calendar and the 70's calendar. I did the same with the right side date codes and found the same. Using both the 60's and 70's Calendars they were also made on weekends.
Initially I thought this would prove the decade by all the centered date codes being built during the week when using the 60's calendar. And the right side date codes being built during the week using the 70's calendar.
I find the same backplates being built on sat and sun on. Either calendar.
EXAMPLE being a centered M/DD/Y ....A065 = Jan 06 1965, Or is it Jan 06 1975?

Dom

[Wayne M.]

Re: Again, A6 compressor backplate date codes?

Dom -- here's a back head from a Friday Oct 18, 1963 cast [ J_18_3 ]. Has all the early features; 440 (stamped) relief valve with the slot (rather than a hole), and the front clutch hub with the 6 small holes.

I have another four or so A6's and will check to see if dates on weekend.

[Domenic T.]

Re: Again, A6 compressor backplate date codes?

Wayne,
Thanks For the pics. I would think that would be a late 63 built for the 64 model year.
I understand that the letter (I) was used in the date code making that a October built. I saw a J ?? 3 code with metal tags, J= Oct, it looked like it was not in use for decades.
I'm going to record your numbers with the ones I have seen.

Dom

[Jeffrey S.]

Re: Again, A6 compressor backplate date codes?

Dom,
I have two A6 compressors on the shelf. One has the date J153 offset to the right port and one G118 in the center. Hope this helps.
Jeff

[Domenic T.]

Re: Again, A6 compressor backplate date codes?

Dom,
I have two A6 compressors on the shelf. One has the date J153 offset to the right port and one G118 in the center. Hope this helps.
Jeff

Jeff,
Thanks, it does. J 15 3 in 1963 or 1973 did not fall on a weekend. 63= Tue, 73=Mon. If it has metal tags then it's for sure a 63. Also the case will not have the swage ni the front. the 68 wcase will have the swage. It also was not built on a weekend. 68= Thurs, 78= Tue and it might have the thermal switch.
If both cases look the same just behind the front mount then the J 5 3 may be a 1973?

Thanks, if you get a chance let me know. I see other markings on the backplates other than the casting # and the date code that might be a key to the decade the codes are.

DOM