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Old 05-09-2025, 09:10 AM
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Heybuck Heybuck is offline
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Default Automatic Temperature Control question?

My 1966 Grand Prix has this option. It worked well after I got the car (26 years ago!!) and after I had a new compressor and a few parts fitted.

It worked till about 6 years ago and firstly the heat failed but it still blew cold but a year or so ago, it all gave up the struggle. No heat, no cold.

So I took the car to an old mate of mine, an auto electrician who understands old GM A/C systems. He has it all working again but he says it needs a new intake manifold temperature sender.

I can't see one on the Ames website but they have a switch PM355 which has two terminals. Anyone have any thoughts on whether this sender will work in my car?

Thanks

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Old 05-09-2025, 10:12 AM
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pfilean pfilean is offline
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I doubt that temp sender has anything to do with the heat/AC systems. But I think the two terminal senders were generally for cars with warning lights only and not gauges. I might expect a GP to have full gauges. And I think the two terminal senders are with one terminal for the green cold light which turns off at 140 degrees and one terminal for the red hot light which turns on at 240 degrees.

  #3  
Old 05-09-2025, 07:11 PM
chiefpontiac66 chiefpontiac66 is offline
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Agree with pfilean. I had a 66 2+2 with auto temp a/c. I had the control head rebuilt and put all new vacuum hoses and actuators in it, along with all new parts out in the engine bay. I don't remember the temperature sender having anything to do with the ATC. That system operated mostly off of vacuum and the temperature sensor on the dash, if I remember correctly.

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Old 05-09-2025, 08:17 PM
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Ian, look for member Margozzi. He totally understands these systems

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Old 05-13-2025, 08:35 AM
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Heybuck Heybuck is offline
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Quote:
Originally Posted by stevep View Post
Ian, look for member Margozzi. He totally understands these systems
Hey, thank you Steve. I'll look him up if the car gives more trouble but right now its running well. I started and drove it on Sunday but the outside temperature was about 21c so the A/C didn't really know what to do. It cycled up to warmish air and down to colder air if I set the temp control hard either way but I think it needs a much colder day to see how the heat works and a lot more heat to see how the cold works.

Right now here in Melbourne we are having very mild days - not really ideal to check the full band of temperature range.

Really appreciate your input guys

Ian

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