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Discussion Starter · #1 ·
Hi the 95 Astro I bought my wife (a Safari really but the same) the control will not shift off defrost and the fan works on the lower 3 of 4 speeds. I found and repaired two vac leaks behind the battery, no change in function but the control actually has vacuum now....... it didn't before. I's not as strong as I think it should be but that could be a perception thing. I tried a known working control replacing the original. No change. I filed the fan ground terminal, no change. I pulled off the connector plug for the vac, and maybe the rotary selector isn't working as it should.....................?????? I'm stumped, any ideas?
 

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Ross,can you tell if the "vendor motor"is working? Look under the dash and see if it is moving when you change your settings.
I had a vendor motor go out on me and it did just what you have described .It' a little white box under the dash and you can usually hear it when you change settings,sometimes they just get stuck and other times they sher of teeth inside the little burger.
Best of luck, let me know what you find out.
 

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Discussion Starter · #3 ·
The vac lines go off to the passenger side where the heater core and AC evap is. Several go into the little pancake shped actualtors, some generally disappear up into the dash. If I pull the radio I should be able to see but maybe I fish my flex scope up in to see if there's anything obvious.
 

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Check the vacum reserve cannister, should be round black plastic tank. Your mode problem definetly sounds like vacum leak. High blower is controlled by a relay fo high speed. Check wiring, many times connector melts from high amperage draw.
 

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Discussion Starter · #5 ·
The fan runs on a single wire through a resistor it's OK on the motor side I haven't checked the resistor side.
Resevoir is OK but I'm still thinking there's not enough vac to actuate the components. Didn't have time to check much yesterday, I certainly wasn't in charge of my time, or I would be caught up in lots of things.
 

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If I remember correctly, the vaccum feed for the vents comes off the the intake on the drivers side under the throttle body.
I have seen alot of those crack at the bend in the vaccum hose at the connection.
You may have to remove the doghouse.
Otherwise it's probably the rotator valve in the control head.
Just a suggestion.
 

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Ross said:
The fan runs on a single wire through a resistor it's OK on the motor side I haven't checked the resistor side.
Resevoir is OK but I'm still thinking there's not enough vac to actuate the components. Didn't have time to check much yesterday, I certainly wasn't in charge of my time, or I would be caught up in lots of things.
The circuit bypasses the resistor and runs thru a relay for high speed. Common tu burn up the connector at the back of the fan speed switch,the relay, or the inline connection.
 

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Discussion Starter · #8 ·
Any idea where under the hood I'd find the resister/replay for the fan? I swapped out the rotary vacuum valve and the vents now switch perfectly. Trying to trace the fan wire back to the relay would be ugly, but the fan switch is good.
 

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Generally the fan resistor in installed into the heater/AC fan housing to help keep it cool. It will be a flat piece with 2 screws retaining it and a few wires going to it that looks like the wires plug into the blower housing itself. Relay is most likely on the pass. side of the underhood area.
 

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Discussion Starter · #10 ·
Thanks that confirms what I've read. There are two relay's on the pass. side and if I could find the resistor I imagine I could sort which is which for the fan control.
 
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