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70 Deville, 90 Allante
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46 Posts
Discussion Starter #1
For over a year or so the when I turn either AC or Heat on the fan doesn't kick in at full speed whether the climate control is set to Auto or HI. It takes a good 15-20 minutes into a drive before the fan kicks in. It doesn't take any shorter a time to come on even when the outside temperature is very cold or very hot. When the fan does come on I hear a very distinctive click which sounds like its right behind the dash. So I’m thinking maybe it’s the Transducer. Any ideas before I go ripping the dash apart?
 

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1970 Coupe De Ville//Cessna 172
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551 Posts
The click you hear is probably the relay on the firewall. To the right (passenger side) on the a/c power servo.
I am having issues with mine too. It worked fine and then I had the engine out and now it isn't.
With the key off, open the hood and move the climate control from left to right. When you get to the middle auto setting the relay should fire. You will hear that click then. My transducer is out on mine too. Cadillac Tim has a book on the climate control that is supposed to be very good. However I have not bought it yet....... The engine kind of took my budget as you can imagine.
Let us know what you find.
Jeff
 

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1970 deville convertible
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204 Posts
Jeff is probably right. I got tims book and went through my hvac last year.

The relay sends extra juice from the starter solenoid when it calls for hi fan speed. It should operate on low even with a faulty relay. Like most relays it can get stuck. I ran a jumper from the battery with the relay disconnected and a few quick hits on the contacts and it became unstuck and works fine now. I was going to replace it they are readily available but haven't had issues since. It's on the firewall to the right of the blower. Should be 4 wires going to it.

I pulled my servo apart and cleaned it up. The problems with those are usually vac related as the valves tend to warp. I bought a refurbished valve from tim too. Problem solved. Good luck.
 
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