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The heater fan sometimes works and other times not.

Tiny
BRUCE KOOP
  • MEMBER
  • 1998 CHEVROLET ASTRO
  • 150,000 MILES
The fan sometimes works and other times not. It either works when I start the vehicle and will work while driving. When I shut the van off and start again it might not work again. It seems as though at times it gets power and other times not.
Sunday, March 11th, 2012 AT 8:55 PM

19 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Probable causes here could be the blower motor, resistor, blower switch and AC/Heater fuse-
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Sunday, March 11th, 2012 AT 9:00 PM
Tiny
LORI JAMIESON
  • MEMBER
  • 2 POSTS
  • 1995 CHEVROLET ASTRO
  • 5.7L
  • 440,600 MILES
Fan is not working on heat/AC.
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuse and fusible link it is a gray wire off of battery junction block. Then check relay on right side of cowl (firewall).
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
LORI JAMIESON
  • MEMBER
  • 2 POSTS
Thank you
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,840 POSTS
Hello,

I have found the fuse and relay location (below) along with a few guides to help you get the problem fixed.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
ANGELEYES_15742
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET ASTRO
1998 Chevy Astro

the blower fan isnt working, have tried changing out the fan, all fuses and relays. Need to know where the resister is located? Thank you so much for your help
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS


https://www.2carpros.com/forum/automotive_pictures/170934_resistor_paint_again_1.jpg



The above picture is the courtesy of autozone, napa has a picture also.

The information for resistor removal, says to remove the air filter housing-- remove container for windshield wiper fluid-- and the container for coolant recovery. You should then be able to get at it.
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
KYLEKIRK
  • MEMBER
  • 1 POST
  • 1998 CHEVROLET ASTRO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
When going uphill, air stops blowing through the vents on the dash. The rear air blower system keeps working fine, and we still get air blowing from the under-dash part of the front blower system, but we get no air flow from the dash vents. The compressor is still working. Once the vehicle is on level ground again, the air flow starts back up through the dash vents. What can cause this problem? Thanks.
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
TECHMAN1
  • MEMBER
  • 82 POSTS
Honest to God, this is not a problem. It is normal for Astro's. I have had 5 of them. The extreme vacuum collapses one of the vacuum control lines between the top of the cowling (above your center glovebox) and the bulkhead connector behind your washer fluid reservoir clear on the back wall of the firewall.

Don't worry about this. This is a non-issue and a non-problem. They all do this.
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Tuesday, April 30th, 2019 AT 4:23 PM (Merged)
Tiny
ASTROAL12
  • MEMBER
  • 1 POST
  • 1996 CHEVROLET ASTRO
Heater problem
1996 Chevy Astro 6 cyl All Wheel Drive Automatic

I have a 1996 Chev Astro Van that the heater/ac blower motor does not work. Put jumper to blower motor and it works. Replaced relay resistor but still does not work. How can I get the wiring diagram for this system. Don't know the procedure for removing the heater control in the dash. Can you tell me the step by step procedure for troubleshooting this problem.
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
CONTROL ASSEMBLY

Removal & Installation
Disconnect negative battery cable. Remove instrument panel bezel. Remove control panel retaining screws. Pull control assembly away from instrument panel.
Disconnect electrical connectors. Disconnect vacuum connectors. Remove control assembly. To install, reverse removal procedure.


https://www.2carpros.com/forum/automotive_pictures/12900_blower_circuit_1.jpg

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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
BLT2GO
  • MEMBER
  • 2 POSTS
  • 1996 CHEVROLET ASTRO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 200,122 MILES
In my 1996 Astro I began to have intermeittent problems with my fan switch working. Then it quit all together. I took it to an automotive electrical shop in Augusta, GA which told me the problem was the dash switch module. We both had checked the fuses and relays but there were none indicating failure. I replaced the dash switch module with a new one but still have no fan, AC, etc that are controlled from the module. Plugs all appear to be in good shape. I had a problem with the driver's door electric window operator which I replaced and works fine now. Should I check the relays again or am I missing something some where? The Augusta electrical 'experts" didn't get it solved.
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Did you bypass the relay, to see if the blower motor would run?

I don't know what tests you've done? The red wire at the relay, should be hot all the time. The purple wire carries voltage to the fan. If you use a jumper wire between those two circuits, the fan should run. You may need to use an inline fuse in the jumper, just to be safe.

According to my info, with the relay energized, only the high speed circuit has continuity to the blower motor.

When you check fuses, you also need to check that one of the terminals is hot, where the fuse plugs-in. Some circuits are hot all the time, some go hot when you turn on the key.
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
BLT2GO
  • MEMBER
  • 2 POSTS
I had jumpered all of the items mentioned with key on and off and the fan runs correctly when jumpered in the engine compartment. Also I have noticed the mileage in the odometer in the dash keeps resetting to 197,377 everytime the car is off for more than 3-5 minutes. The AC appears to be OK but I can not really check the functionality of the compressor clutch without the other dash switches working so I can check cool air flow. I will check the power 'hot' on one side of each fuse with key off, on and with vehicle running and the other switch in place even though the fan is not running nor the AC clutch engaging. It's been a while so I don't remember if I check the terminal potentials. I have another item which is much older than this which is the 4L60E trans hard closing the R, 1-2, and 2-3 shifts. Could all of these issues emminate from a failed or failing computer? Thanks.
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I don't believe the vcm has any control over the blower motor. On your other two issues, it is possible but not probable. There is a whole list of things I would check before the computer.

Can you check codes? Some of the national brand autostores will check codes for free.

As far as the front blower, you can turn the key on, you don't have to start it, turn the hvac control on normal and the blower switch on high. Try to check the wires at the relay without unplugging the connector, backprobe. The orange-- red--- purple wire should have good voltage?
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
SK
  • MEMBER
  • 1 POST
  • 1994 CHEVROLET ASTRO
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 191,000 MILES
My heater was going strong and then suddenly stopped working, I think its just the fan as there seems to be warm air coming out, but no fan to force it. Any tips please.
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
JUSTIN FREED
  • MEMBER
  • 87 POSTS
Before you go digging into the car and taking things apart, start looking for simple things - like fuses, for example. Also, check switch positions, and sometimes, fans are automatically controlled - although, not on a '94 astro, I'm pretty sure.

If nothing materializes there, then you need to start looking deeper. If you plan to do the work yourself, you really need to invest in a decent repair manual; one w/ wiring diagrams etc. Because the fan motor might be bad but it could also be a relay or something like that. Without a decent schematic, you will have a tough time. Good luck!
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
TEKNOFSKY
  • MEMBER
  • 1 POST
  • 1994 CHEVROLET ASTRO
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 20,692 MILES
The blower for the heater/defog stopped working. When driving for awhile, it will turn on ocasionally. Not sure if it is a switch or the motor itself because when it does turn on, it seems to be working fine.
Please advice, 20 degrees today in Michigan :)
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,133 POSTS
Hi:
It could be the switch or the motor. But, it could be a relay or a blower motor resister. You need to check for power to the motor. If there is power, the motor is bad. If there is no power, work back to the switch, resister, relay, switch. Where there is power in and none out, that will be your problem.

Joe
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Tuesday, April 30th, 2019 AT 4:24 PM (Merged)

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