I have for sale a NOS air conditioning thermal limit switch for the AC compressor, AC Delco part number 6556440, Group 15-279. This is in excellent condition. $25 or best offer, buyer pays shipping cost. Here's some pics:

 

This AC thermal limit switch for the AC compressor is still for sale!

 

Message sent.

 

Anthony:
I didn't get your PM. Would you like to buy the Thermal switch?

Rodney

 

Sent you message via email. Is this thermal limit switch just for the '72 model year?

 

Rock Auto lists this AC Delco part and it's SMP equivalent (TLS1) for all Oldsmobile models from 1964-1978, but I don't see it shown in the A-body assembly manuals prior to 1972. The '69 & '70 models had a "hold-in" relay to energize the compressor clutch and the '71 model is identical to '72 but doesn't have this part. I think starting in '72 the AC compressor had a feature called "superheat" that requires the thermal limiter. If the pressure gets too high at the compressor, the superheat switch will short the thermal limiter to ground and blow the internal fuse inside the thermal limiter to cut power to the compressor.

I see some AC houses selling A6 compressors with a high-pressure switch instead of the superheat switch. This switch works exactly opposite from the superheat switch and does not require the thermal limiter. The high-pressure switch completes the ground for the compressor clutch and will open when the pressure gets too high to cut power. Once the pressure falls to a safe level, the switch resets and the system will continue to work again.

 

Thank you very much for explaining the differences. I did not know the subtle A/C differences between the years.

 

My 73 Custom Cruiser had this Thermal Limiter Switch. When refrigerant was too low it would blow the limiter and protect the compressor. At the time they were a 25¢ part at almost every boneyard.

 

Still for sale! A NOS air conditioning thermal limit switch for the AC compressor, AC Delco part number 6556440, Group 15-279. This is in excellent condition. $25 or best offer, buyer pays shipping cost.

 

Still for sale.

 

Still for sale! A NOS air conditioning thermal limit switch for the AC compressor, AC Delco part number 6556440, Group 15-279. This is in excellent condition. $20 or best offer, buyer pays shipping.

 

I still have for sale a NOS air conditioning thermal limit switch for the AC compressor, AC Delco part number 6556440, Group 15-279. This is in excellent condition. $25 or best offer + shipping from Houston, TX.Rodney

 

I still have for sale a NOS air conditioning thermal limit switch for the AC compressor, AC Delco part number 6556440, Group 15-279. This is in excellent condition. $25 or best offer + shipping from Houston, TX.Rodney

 

Ttt

 

Still for sale.

 

Still for sale!

 

Still for sale.

 

When I was a kid I recall these blowing pretty regularly. Such a common occurrence that the corner drug store actually had these on their rack!