Fan always on high in A/C position

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Old October 13th, 2018, 08:46 AM
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Fan always on high in A/C position


On my 72 Delta 88 I have an A/C blower issue I have not seen before and since this is a new ride for my I am unsure if it is normal operation. I dont think so but stranger things have happened. On all positions except A/C my blower works as you would expect it to. However in the A/C postion, all blower speeds are high. If you have the A/C on the blower is on high, thats it. I replaced the relay because it was bad to get it to operate where it is now. I see there is a 2nd relay positioned under the one I replaced but am unsure of its purpose. I also know there is a resistor in the box, however It seems to be working on all but the A/C positions.
Thanks
Roy

Last edited by Fastmax32168; October 13th, 2018 at 10:46 AM.
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Old October 13th, 2018, 05:49 PM
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Pretty sure the second relay under hood is the compressor relay. I’m not real familiar with the options available on the 72 88, does it have the automatic climate control?
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Old October 13th, 2018, 08:13 PM
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Here's a shot in the dark. Does your car have a rear window defogger? If so, is it switched on?

Check out the blower diagnosis chart below, which is from the '72 Olds chassis service manual. (You do have this manual, right?)

Look at the far left column, which seems to come closest to describing your problem---the blower motor is on high in all A/C positions.

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Old October 13th, 2018, 08:18 PM
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If the temp control slider is all the way to the left, the cold side, move it slightly to the right. It's probably in the MAX AC position. Moving it off of that will let you use the blower speed selector. Simple things first.
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Old October 14th, 2018, 02:56 AM
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So it turns out Blakes is right and I am 0 for 2 on the "how many fastmaxes does it take to work an Oldsmobile test" I moved the lever off the far left and voila, fan control return! Oh brother, time to go play with my lego logs I guess.
Thanks,
Roy
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Old October 14th, 2018, 11:01 AM
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It's hard but you can feel a spot where it goes into the MAX position. The owner's manual tells you this, also. When you said it only happens when you put the AC on, that is what told me this was the case.
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