A/C Blower Motor not working - JeepForum.com

 
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post #1 of 7 Old 09-11-2016, 04:33 PM Thread Starter
dgmwrangler
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A/C Blower Motor not working

I have been reading posts on problem. I had this problem several years ago and was able to fix them. I have so far replaced resistor, relay, speed switch and vacuum switch. Actual blower is three years old, replaced last go around. My problem seems more related to the fact I don't have power at the blower fan fuse behind the glove box. Any clues as to what I could check. I pulled off and saw no melt wire or any other obvious problems. Thanks

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post #2 of 7 Old 09-11-2016, 10:31 PM
timatoe
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You need to provide a little bit of information, like what year etc your Jeep it. The A/C and heater use two different fans. I don't think the things you've reference are for the A/C, but rather for the heater. I very well could be wrong, I don't have A/C.

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post #3 of 7 Old 09-12-2016, 10:05 AM Thread Starter
dgmwrangler
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Sorry about that. Its a 99 Wrangler, 4.0L. The A/C unit comes on when the switch is turned on because when you its on you feel the load on the engine come up. I was having some intermittent problems with the fan blower and noticed when it didnt work I had no power to the #8 fuse on the fuse block behind the glove box. But now there is no power to it at all. I did also run the fan remotely and it works fine. Is there something between the ignition and the fuse box that could control the #8 fuse?
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post #4 of 7 Old 09-12-2016, 10:59 AM
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It looks like fuse 8 powers the relay coil and fuse 11 in the PDC feeds the load circuit.
Attached Thumbnails
1999 TJ Blower Motor (8W-42-3).png  

1995 JY YJ
2014 JK, MC GCL 2.5", 35x12.5x17, 4.56s.

My observations are based on my experiences...YMMV.
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post #5 of 7 Old 09-12-2016, 11:29 AM Thread Starter
dgmwrangler
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Thanks for the diagram, Unfortunately my electronic skills aren't so great and its all kinda "greek " to me. I did check the fuses in the main fuse box under the hood with a test light and saw no problems with the fuses I could easily test, but refer back to my earlier skills statement.
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post #6 of 7 Old 09-12-2016, 12:22 PM
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Fuse 2 in the PDC and fuse 8 in the fuse box both feed the control circuit. Fuse 11 in the PDC feeds the load circuit. So with the key in the run position, you should have 12V at pin 9 of the HVAC unit. You should also have 12V at pin 8 of the HVAC unit always.

If you're interested in learning how to read these things, see if you can follow along. The flow goes as follows...

Page 8W-10-6
Positive terminal from battery to pin 8 of the PDC via circuit A0. Pin 8 then connects to fuse 2. It comes out of the PDC from fuse 2 through pin 1 and then goes to pin 3 of the ignition switch via the A2 circuit.

Page 8W-10-8
When the ignition switch is in the run position, power is sent out pin 4 of the ignition switch to pin 5 of the fuse block via circuit A22. It then runs through fuse 8 in the fuse block and out pin 28.

Page 8W-42-3
Out pin 28 of the fuse box to pin 5 of the HVAC Unit via circuit F24. Pin 5 is jumped to pin 9 which feeds the blower motor relay coil. The other side of the coil goes to ground via pin 10. When the coil is energized, it closes the internal relay load switch. This allows the feed from fuse 11 to enter the relay through pin 8 of the HVAC unit which then feeds the blower motor. The other side of the blower motor comes out pin 7 and is connected to the AC Heater Control pin A via circuit C7.
Attached Thumbnails
1999 TJ Power Distribution (8W-10-6).png   1999 TJ Power Distribution (8W-10-8).png   1999 TJ Blower Motor (8W-42-3).png  

1995 JY YJ
2014 JK, MC GCL 2.5", 35x12.5x17, 4.56s.

My observations are based on my experiences...YMMV.
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post #7 of 7 Old 09-12-2016, 12:28 PM
timatoe
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Quote:
Originally Posted by dgmwrangler View Post
Sorry about that. Its a 99 Wrangler, 4.0L. The A/C unit comes on when the switch is turned on because when you its on you feel the load on the engine come up. I was having some intermittent problems with the fan blower and noticed when it didnt work I had no power to the #8 fuse on the fuse block behind the glove box. But now there is no power to it at all. I did also run the fan remotely and it works fine. Is there something between the ignition and the fuse box that could control the #8 fuse?
You may get better responses in the TJ section, but have you pulled the actual control section out of the dash?

Our '01 TJ blower quit working. I found that jumping the blower direct to the battery it would power on. More research found that the blowers will start to short out and burn up the switch in the main controller. I replaced the blower motor and the switch and had to make a new connector to the switch at the OE one had melted. Apparently this is a fairly common failure.

I don't remember doing anything at the fuse except check the fuse itself.

**EDIT** Just re-read your initial post. If you've replaced the switch, did any of the wiring look melted?

Quote:
Originally Posted by George Orwell
We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm.
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