A/C blower fan slows down by itself.
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Drifting
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From: Iowa
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A/C blower fan slows down by itself.
Had the A/C on today (mid 90's outside) and everything just fine. About after a half-hour running fan on hi-speed, it slows down all by itself to what amounts to lo speed as far as moving air out the vents.
Pull over, shut everything down, look around, start it back up....fan runs normal again, pushing lots of air. Half hour later it slows down.
What gives? Any ideas what to check? It's a '96 LT1.
Pull over, shut everything down, look around, start it back up....fan runs normal again, pushing lots of air. Half hour later it slows down.
What gives? Any ideas what to check? It's a '96 LT1.
Burning Brakes
Joined: May 1999
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From: Spring Texas
Re: A/C blower fan slows down by itself. (MagikDraggin)
Magik: You might try looking under the fuel rail cover on the passenger side or just forward of that for the vacuum connector for your air distribution doors in the air control system . There have been a lot of threads concerning either rotted out vacuum hose connection, slight disconnect from the vacuum inlet on the right side of oyur intake area, or a cracked plastic connector which distributes the vacuum lines. This happened to my '94 last month just like yours and I found my inlet hose slightly off the connection to the engine. I slipped it on and no more slowing of the air blower.
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Drifting
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From: Iowa
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Re: A/C blower fan slows down by itself. (jiml94)
Man, if it wasn't for your response, I wouldn't have anything to go on. Is that why I'm not getting anything from anyone on this??? Just because it's been discussed before......like I would know this?
I did a search, but as usual, came up with a no match.
I appreciate your effort. It is something to check out and makes sense. Thanks
I did a search, but as usual, came up with a no match.
I appreciate your effort. It is something to check out and makes sense. Thanks
Burning Brakes
Joined: May 1999
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From: Spring Texas
Re: A/C blower fan slows down by itself. (MagikDraggin)
Magik: Here is another thread: I found it thru the search feature. It is "Delayed AC Top Vent Output" by 1Patriot at 1:54PM on 4/19/2002 . Use key words in topic title, archived topics, C4 tech /performance forums to find it. Also I do not know if you are aware that when the AC is in the auto mode climate control selector, that the AC blows hard at first and slows down to match the temperature setting that you have selected. The fan speeds change as the ac cools to that temp. The 1Patriot thread talks about the vacuum fittings problem. Ahh, I found it! Posted by Ultra at 4:21pm on 7/14/2003 "No Air Coming Out of AC Ducts" C4 Tech/Performance Forum Good Luck
[Modified by jiml94, 8:59 AM 8/17/2003]
[Modified by jiml94, 9:17 AM 8/17/2003]
[Modified by jiml94, 8:59 AM 8/17/2003]
[Modified by jiml94, 9:17 AM 8/17/2003]
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From: Evans, GA
Re: A/C blower fan slows down by itself. (MagikDraggin)
If you have the climate control in the LT1 and the problem is as posted, then you need to check the following: Is the dash control set for auto, is so, the lowere the temp selection and the fan should speed back up. If set on Non-auto then the fan speed should only change as you increase or decrease the fan speed from the fan selector switch.
When the AC/heater is on auto, the programmer controls the fan speed based on the setting of the tempreture selection and the sensor in the dash to match the needs based on the tempreture of the air inside the vehicle. If you want the fan to run at the speed you select, then turn the control head to your manual choice and adjust the fan and the tempretue range to suit you.
Do ypu have the owners manual for this car??
When the AC/heater is on auto, the programmer controls the fan speed based on the setting of the tempreture selection and the sensor in the dash to match the needs based on the tempreture of the air inside the vehicle. If you want the fan to run at the speed you select, then turn the control head to your manual choice and adjust the fan and the tempretue range to suit you.
Do ypu have the owners manual for this car??
Thread Starter
Drifting
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From: Iowa
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Re: A/C blower fan slows down by itself. (1Patriot)
Yes, I have the owners manual. And no this car does NOT have the auto-air option. It is strictly manually operated.
I still have the function of a 4 speed selector switch on the fan, but the output is severly reduced to where the output in setting #4 SEEMS like setting #1. That is until I shut the car off.....allow the refrigerant to "equalize" and then fire it back up and voila, fan works normally again.....that is until about 30 minutes or so, when it suddenly slows down again.
Now, I have noticed today, that with the air on and the fans doing their "slow-down act, if I push the button that selects recirc air, the fan sounds like it is roaring like hell, but there is still no or little air moving out the vents.
I would therefore surmise the problem lies in the vacuum selection of the diverter doors themselves.
I still have the function of a 4 speed selector switch on the fan, but the output is severly reduced to where the output in setting #4 SEEMS like setting #1. That is until I shut the car off.....allow the refrigerant to "equalize" and then fire it back up and voila, fan works normally again.....that is until about 30 minutes or so, when it suddenly slows down again.
Now, I have noticed today, that with the air on and the fans doing their "slow-down act, if I push the button that selects recirc air, the fan sounds like it is roaring like hell, but there is still no or little air moving out the vents.
I would therefore surmise the problem lies in the vacuum selection of the diverter doors themselves.
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Drifting
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Re: A/C blower fan slows down by itself. (jiml94)
Finding the correct "key word" is obviously the "key" to using that search feature. I usually don't have much luck in ever finding anything.
But thanks for the tip and I am heading there to check that post right now.
Keep in mind my Corvette does not have the "auto-air" option.....it is purely manually operated.
Thanks
Ok, read the thread.....btw, I failed to use the "archived" option.....that explains why I could never find anything.
Anyway, my problem is just the opposite of theirs. Where they have no air out the front vents for awhile after the A/C is turned on, I do and plenty of it. It after awhile, AFTER it is running that my fan slows down, and the interior gets very warm rather quickly I might add. I have not know the fan to come back up to speed on its own unless I shut the A/C off and restart it after a few minutes.
Does that help any?
Karl
[Modified by MagikDraggin, 12:19 PM 8/17/2003]
But thanks for the tip and I am heading there to check that post right now.
Keep in mind my Corvette does not have the "auto-air" option.....it is purely manually operated.
Thanks
Ok, read the thread.....btw, I failed to use the "archived" option.....that explains why I could never find anything.
Anyway, my problem is just the opposite of theirs. Where they have no air out the front vents for awhile after the A/C is turned on, I do and plenty of it. It after awhile, AFTER it is running that my fan slows down, and the interior gets very warm rather quickly I might add. I have not know the fan to come back up to speed on its own unless I shut the A/C off and restart it after a few minutes.
Does that help any?
Karl
[Modified by MagikDraggin, 12:19 PM 8/17/2003]
Burning Brakes
Joined: May 1999
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From: Spring Texas
Re: A/C blower fan slows down by itself. (MagikDraggin)
Karl: I believe that the problem still lies in the vacuum connection. Especially noting that once you start it up again, it owrks. That would indicate that the car builds up vacuum again . Did you check that area yet? I am curious to find out. Jim L 94
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From: Evans, GA
Re: A/C blower fan slows down by itself. (MagikDraggin)
The vacumn canister should be holding the vacum constant. If not it may be leaking or have a defective hose. When I drove the 88 coupe, it had a manual system and the lever to the heat/cool selection disengaged and I had to remove dash to repair. But this does not appear to be your problem. Sorry, I no longer have the repair manual for the 88.
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Drifting
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Re: A/C blower fan slows down by itself. (jiml94)
Yes, I took the rail cover off...found the tee you were mentioning and everything looks just fine. All the hoses are soft and pliable, no cracks or melted places.
Where exactly is this vacuum cannister located on a 96?
It would appear as though the motor is not slowing down, as much as it is the damper doors throttling down the air flow.
It was mentioned that on an "automatic air" equipped car, these functions are computer controlled.....does that mean the same computer that controls engine functions, or is there another unit specifically for the A/C system?
Mine is NOT the auto-air, but I was wondering if maybe somehow it is set up so that the computer THINKS that it is. (I hope that doesn't sound too stooopid).
Thanks for the suggestions so far.
Karl
Where exactly is this vacuum cannister located on a 96?
It would appear as though the motor is not slowing down, as much as it is the damper doors throttling down the air flow.
It was mentioned that on an "automatic air" equipped car, these functions are computer controlled.....does that mean the same computer that controls engine functions, or is there another unit specifically for the A/C system?
Mine is NOT the auto-air, but I was wondering if maybe somehow it is set up so that the computer THINKS that it is. (I hope that doesn't sound too stooopid).
Thanks for the suggestions so far.
Karl
Thread Starter
Drifting
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From: Iowa
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Re: A/C blower fan slows down by itself. (1Patriot)
Ok, found the vacuum canister.....wasn't at all what I was expecting it to look like. Dont know how to "test it" (other than to disconnect it and see if vacuum is present) but the line coming from it was in good shape and no signs of aging.
By the way, I operated the other buttons on the controller, (like the one that directs the air flow to the vents and to the floor, and while the air flow stayed the same, the cold air stopped, until I pushed the button again that actually says A/C on it. That's not right, is it?
Anything else I should check out?
By the way, I operated the other buttons on the controller, (like the one that directs the air flow to the vents and to the floor, and while the air flow stayed the same, the cold air stopped, until I pushed the button again that actually says A/C on it. That's not right, is it?
Anything else I should check out?
Burning Brakes
Joined: May 1999
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From: Spring Texas
Re: A/C blower fan slows down by itself. (MagikDraggin)
Karl: I think you should look at your owner's manual for the correct operation of those buttons. If you hit the air direction buttons after having the AC on, you will shut off the ac. if you hit the AC button again, the ac should return. In GM cars, the air distribution buttons are not part of the ac system. The AC will come out the top vents. If you hit any others, the AC goes off. Only ouside air then comes in to the system. I believe your system buttons are working right. Where was the canister? Other threads still talk aboput a air vacuum controller underneath the dash.depending on what year you have.I just looked at my Haynes manual for corvettes, and in Ch.6 the emissions and engine control systems chapter, there is a picture of the canister purge solenoid located on the right side of the intake manifold (next to the fuel rails underneath the plastic cover which I believe is what we have been calling the tee fitting. it looks exactly like mine. Anyway, since the call it a solenoid, perhaps this is what is not operating correctly.This solenoid really controls the fuel vapor canister so i am not sure of all of its connections.
[Modified by jiml94, 10:07 PM 8/17/2003]
[Modified by jiml94, 10:07 PM 8/17/2003]
Thread Starter
Drifting
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From: Iowa
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Re: A/C blower fan slows down by itself. (jiml94)
The thing I found was a basically round ball about 5" in diameter, locate in the recess near the driver's side headlight...not far from where that little air pump is for the emissions controls.
Everything is all buttoned up now for the evening and I must take the daughter to Chicago tomorrow and may be stuck there for a couple days. I'll check out what you suggested when I get back.
Thanks for your assistence.
Karl
Everything is all buttoned up now for the evening and I must take the daughter to Chicago tomorrow and may be stuck there for a couple days. I'll check out what you suggested when I get back.
Thanks for your assistence.
Karl
