1974 HVAC Blower Relay Part Number Question

[Victor S.]

Aim says part number is 1115881, Judging Guide shows part number 3992131 - which is factory correct?

Thank you

[Jimmy P.]

1115881 as you note. But the AIM also listed two other possible part numbers for the relay. (See attached photo). When researching the 1115881Hope this helps clarify things.

[Tom R.]

Re: 1974 HVAC Blower Relay Part Number Question

Vic,
When we were revising the 73-74 manual we did discuss this very thing. The photo of the 3992131relay on page 154 in newest 3rd edition is from a ‘73 LS4. We had another team member with a ‘74 LS4 and the part number on his relay was 2072624 ( also found on many other GM vehicles). We saw that the ‘74 AIM listed the part number 1115881 as you note. But the AIM also listed two other possible part numbers for the relay. (See attached photo). When researching the 1115881 it appeared to be a very common relay used on most GM lines from 69-77. It had several different looks in various photos. We also learned that the earlier relays before mid/late ‘71 were black with rounded corners and had the Delco-Remy logo on them vs. the later zinc ones with squared corners and no DR logo. Therefore, we added that sentence…GM used multiple suppliers and part numbers may vary.
Hope this helps clarify things.

Victor
The revision team really scrubbed these sort of conflicting sources vs. what was seen on known original configurations and why that "clarifying sentence" was included.

We also noted that there are few absolutes when studying late-model C3 vehicles and when attempting to source published data with actual installations.

[Joe L.]

Re: 1974 HVAC Blower Relay Part Number Question

Aim says part number is 1115881, Judging Guide shows part number 3992131 - which is factory correct?

Thank you

Victor------

GM #1115881 is a Delco-Remy part number. Following normal Delco-Remy practice, these were probably stamped with the last 3 digits of the part number and somewhere embossed "Delco-Remy". Early examples had the cover painted black and later were zinc plated. This part was once available in SERVICE but was discontinued in March, 1982 (about the time that Delco-Remy ceased manufacture of such relays) and replaced by GM #2072624. I expect the latter is a "generic" piece manufactured by a non-GM parts manufacturing entity. It is also now discontinued without supercession.

GM #3992131 and 3992132 are Chevrolet part numbers. These were never available in SERVICE. They may have been manufactured by Delco-Remy and, if so, I would expect them to appear just like the 1115881 or they may have been manufactured by non GM suppliers to the same standard as the 1115881 but without any sort of Delco-Remy identification. My expectation would be that few, if any, of the 3992131 or 3992132 were ever actually used in PRODUCTION, especially earlier in the PRODUCTION period.