1970 AC Expansion Valve

[Mark E.]

I'm shopping for an AC expansion valve for a 1970. The car has what looks like its original Frigidaire. No PN on its body.

My 1978 Parts Catalog says the service PN is 5910767 and is used for 68-72.

I found two NOS Frigidaire valves which externally look identical to the one on the car. Their PN is 5910619. Will these work? They will physically fit, but I wonder if they have a different calibration, hence the different PN. Or if this is an older/newer service PN?

[Terry M.]

Re: 1970 AC Expansion Valve

I'm shopping for an AC expansion valve for a 1970. The car has what looks like its original Frigidaire. No PN on its body.

My 1978 Parts Catalog says the service PN is 5910767 and is used for 68-72.

I found two NOS Frigidaire valves which externally look identical to the one on the car. Their PN is 5910619. Will these work? They will physically fit, but I wonder if they have a different calibration, hence the different PN. Or if this is an older/newer service PN?

Mark
As a generalization the service expansion valves have a longer capillary tube so they will fit many applications. The PRODUCTION expansion valves have a capillary tube that is quite short; just long enough to reach the pipe on the evaporator.. I just took a quick look in one of my 1970 AIMs and found no part number for the PRODUCTION expansion valve. I expect it came as part of a valve and pipe assembly.

That aside I have seen a few expansion valves that have a date steel stamped on them. Those I have seen have not come from Corvettes, however I have no reason to think there is a date code on Corvettes -- nor do I have any reason to think there is not one. The date, if any, is not in an easy to see location -- so that is one blessing. (See this IS beginning to sound like a religion, as Joe L pointed out in another thread.)

[Joe L.]

Re: 1970 AC Expansion Valve

I'm shopping for an AC expansion valve for a 1970. The car has what looks like its original Frigidaire. No PN on its body.

My 1978 Parts Catalog says the service PN is 5910767 and is used for 68-72.

I found two NOS Frigidaire valves which externally look identical to the one on the car. Their PN is 5910619. Will these work? They will physically fit, but I wonder if they have a different calibration, hence the different PN. Or if this is an older/newer service PN?

Mark------


The original A/C expansion valve for 1970 Corvettes was GM #5910657. This was discontinued in October, 1970 and replaced by GM #5910767. The latter lasted until the mid 1980's when it was replaced by GM #6551449. This was followed by GM #12363651 and, later, GM #12356572. The latter is now discontinued. An AC/Delco part survives but not of OEM quality. It is GM #19189767.

GM #5910619 is applicable to 1967-70 Chevrolet and other GM passenger cars of the late 60's. It was discontinued in November, 1970 and replaced by GM #5910745.

Will the 5910619 work for a Corvette? That I do not know.

[Larry M.]

Re: 1970 AC Expansion Valve

I would expect the TXV calibration to be similar or same. The difference primarily being in the length of the capillary tube for different applications.

These were early days for auto AC, and I do not believe the GM/Fridigare factory was making too may variations for each model car. The A6 compressor capacity was pretty much fixed at around 27,000 BTU/HR. R12 was the only refrigerant. An the evaporator superheat target was the same at around +10F (40-45 F actual).

I would check TXV for open/close operation, clean it up, install a new inlet screen, and use it. Open/close check with hair dryer and with ice bath.

Larry

[Mark E.]

Re: 1970 AC Expansion Valve

Mark------


The original A/C expansion valve for 1970 Corvettes was GM #5910657. This was discontinued in October, 1970 and replaced by GM #5910767. The latter lasted until the mid 1980's when it was replaced by GM #6551449. This was followed by GM #12363651 and, later, GM #12356572. The latter is now discontinued. An AC/Delco part survives but not of OEM quality. It is GM #19189767.

GM #5910619 is applicable to 1967-70 Chevrolet and other GM passenger cars of the late 60's. It was discontinued in November, 1970 and replaced by GM #5910745.

Will the 5910619 work for a Corvette? That I do not know.

Thank you Joe!

Where do you find all of this information?

[Mark E.]

Re: 1970 AC Expansion Valve

I would expect the TXV calibration to be similar or same. The difference primarily being in the length of the capillary tube for different applications.

These were early days for auto AC, and I do not believe the GM/Fridigare factory was making too may variations for each model car. The A6 compressor capacity was pretty much fixed at around 27,000 BTU/HR. R12 was the only refrigerant. An the evaporator superheat target was the same at around +10F (40-45 F actual).

This would be great news, since I haven't found the specific PN for this car, but have found NOS TXVs that look identical but with different PN.
The Corvette A6 is a smaller displacement, and it may spin at a different speed. Would that be a reason for a different calibration?

I would check TXV for open/close operation, clean it up, install a new inlet screen, and use it. Open/close check with hair dryer and with ice bath.

Larry

This is an intriguing idea. The original "worked when parked" 25 years ago, and the system remained sealed. Any suggestions where to get more detail about testing? For example, what temp should it open/close? And I assume the temp sensor bulb is what is heated and cooled...

[Larry M.]

Re: 1970 AC Expansion Valve

Mark:

I have posted the test procedure here before, but I will do it again for you. From AutoZone Technical Library. I can/will help you interpret the procedure if you need.

I will find the link and add it in a minute. Here is the link: https://www.autozone.com/repairinfo/...&subtitle=test

Larry

PS: The original TXV valve for my 1967 car continues to work after 51 years.................so yours may also.

PSS: Classic Auto Air in Florida also states that they can recondition and test TXV valves. Another way to go for you.

[Mark E.]

Re: 1970 AC Expansion Valve

Thanks Larry!

I did find an old post of yours with info about the inlet screen:
ACDELCO #15-512
It crosses over to GM #5914631 and NAPA #TEM 207342.

[Harry S.]

Re: 1970 AC Expansion Valve

All I did with mine is take it out of the car and try to blow through it. Nothing happened. At room temp you should blow air easily. The valve was jammed shut.

On my NOS replacement I did the same test and air flowed freely at room temp. I then put in the freezer for 20 monutes and did the same test. No air would flow till the bulb warmed. Installed the valve and the A/C is fine. Running R12

[Larry M.]

Re: 1970 AC Expansion Valve

Thanks Larry!

I did find an old post of yours with info about the inlet screen:
ACDELCO #15-512
It crosses over to GM #5914631 and NAPA #TEM 207342.

These are VERY hard to find anymore. Long gone. If you cannot find, let me know......I will help you.

[Mark E.]

Re: 1970 AC Expansion Valve

Thanks Harry.

[Mark E.]

Re: 1970 AC Expansion Valve

These are VERY hard to find anymore. Long gone. If you cannot find, let me know......I will help you.

Thanks for offering to help, Larry. Stay tuned as I look for a screen.

[Mark E.]

Re: 1970 AC Expansion Valve

Mark------

The original A/C expansion valve for 1970 Corvettes was GM #5910657. This was discontinued in October, 1970 and replaced by GM #5910767. The latter lasted until the mid 1980's when it was replaced by GM #6551449. This was followed by GM #12363651 and, later, GM #12356572. The latter is now discontinued. An AC/Delco part survives but not of OEM quality. It is GM #19189767.

GM #5910619 is applicable to 1967-70 Chevrolet and other GM passenger cars of the late 60's. It was discontinued in November, 1970 and replaced by GM #5910745.

Will the 5910619 work for a Corvette? That I do not know.

How can I look up the PNs which superseded 5910619? If they are the same PNs which superseded 5910657, then that is a clue that 5910657 and 5910619 interchange.

[Joe L.]

Re: 1970 AC Expansion Valve

How can I look up the PNs which superseded 5910619? If they are the same PNs which superseded 5910657, then that is a clue that 5910657 and 5910619 interchange.

Mark------


You probably can't look it up but I can. GM #5910619 was discontinued and replaced by GM #6551448. The latter was discontinued and replaced by GM #12363651. As you can see from my previous post, GM #12363651 was also one of the later supersessive part numbers for the GM #5910657. So, we know that GM #12363651 is REARWARD compatible with both the GM #5910657 and GM #5910619. However, that does not necessarily mean that the 5910657 and 5910619 are functionally equivalent. It just means that GM came up with a part in SERVICE that "one size fits all". So, it might mean that a 5910619 could be used to replace a 5910657 or it might not. I would say that if the 5910657 and 5910619 are, outwardly, absolutely identical, then there must be some internal difference. If they are not outwardly absolutely identical, then that may be the only difference.

[Mark E.]

Re: 1970 AC Expansion Valve

Thanks Joe!

Larry posted earlier the difference may be the length of the equalizer and temperature sensor tubes. I've asked the seller of the 5910619 for these lengths so I can compare to my 5910657. If they're a bit different but will work, this may be an option. I'm hoping 5910619 will work because from the photo it looks like 5910657, and it's NOS.

How do you look up this information? Is there a special book or database? I have a 1978 Parts Catalog for Corvette, but it lists only the PN current at that time, not the original or preceding numbers.