1996 Chevy Astro Htr/AC/Fan Not Working

Tiny
BLT2GO
  • MEMBER
  • 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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Thursday, September 4th, 2008 AT 10:19 AM

3 Replies

Tiny
JDL
  • EXPERT
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, September 9th, 2008 AT 12:36 PM
Tiny
BLT2GO
  • MEMBER
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, September 9th, 2008 AT 12:58 PM
Tiny
JDL
  • EXPERT
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, September 9th, 2008 AT 3:17 PM

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