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Blower Motor only works on low

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Old 08-02-2009, 03:56 PM   #1
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Blower Motor only works on low

Couldn't find the previous thread I'd started about this. See my sig for my truck info.

Anyways, my blower/fan motor only blows on low. I can have the switch on high, turn the key on, get under the hood and unplug the motor...and when I plug it back up, the motor blows wide open like it should. Yet when I turn the key off, then back on again, it's back to only blowing on low.

Okay, so I replaced the blower motor; that didn't fix the problem, it still only blows on low. Now there is a rack of 3 relays on the firewall, and the middle one is the blower motor relay. With the key on, you can "thump" the relay with your finger and it'll start blowing wide open like it should; yet as before, if you kill the fire and turn it back on, it only blows on low. So I replaced the relay with a new one. Same problem; only blows on low, you can thump/bump it and it'll blow on high. So it's not the relay either.

What else could it be?
Old 08-02-2009, 04:11 PM   #2
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Re: Blower Motor only works on low

Blower motor resistor is my next guess.
Old 08-02-2009, 04:19 PM   #3
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Re: Blower Motor only works on low

Quote: Originally Posted by jtcfanof3
Blower motor resistor is my next guess.


x2.
Old 08-02-2009, 04:23 PM   #4
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Re: Blower Motor only works on low

Quote: Originally Posted by Mattpyle
x2.
x3.
Old 08-02-2009, 04:28 PM   #5
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Re: Blower Motor only works on low

Where is the resistor? It wasn't on the blower motor or housing.
Old 08-02-2009, 04:30 PM   #6
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Re: Blower Motor only works on low

You can always remove it and test it for sure,I dont know the specs on your 95 but Im sure they can be found. Hell I found em for a 96 Econoline van I worked on last week,same thing!
LOL
Old 08-02-2009, 04:34 PM   #7
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Re: Blower Motor only works on low

Its on the blower box,should be kinda flat.
Look for this outer portion:

See it in this pic?:

I know,its hard to see past the LS motor!

Last edited by jtcfanof3; 08-02-2009 at 04:40 PM.
Old 08-02-2009, 04:39 PM   #8
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Re: Blower Motor only works on low

Where is the resistor?
Old 08-02-2009, 04:43 PM   #9
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Re: Blower Motor only works on low

Quote: Originally Posted by SD44
Where is the resistor?
Old 08-02-2009, 04:57 PM   #10
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Re: Blower Motor only works on low

Kool. When I go to the parts store, do I just tell them it's the blower motor resistor?
Old 08-02-2009, 06:08 PM   #11
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Re: Blower Motor only works on low

Yeah,unless you check it and its good. Look up the ohm readings on it and see if it truly is bad. I would test it,I meen usually a resistor goes bad and the blower only works on high. Double check all your grounds and such.

Last edited by jtcfanof3; 08-02-2009 at 06:12 PM.
Old 08-02-2009, 06:18 PM   #12
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Re: Blower Motor only works on low

Don't want to buy anymore parts I don't need; how can I test the resistor? I went out there and swapped those relay around, since all 3 are the same. I can turn the key on, and tap the resistor on the blower box and it doesn't make it blow on high. I can tap the two outer relays, and nothing happens. But I can tap the middle relay and the blower kicks on high; no matter which relay I have put there. Wtf?
Old 08-02-2009, 07:01 PM   #13
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Re: Blower Motor only works on low

Or could it be a bad wire or connection? Just an idea if its not the resistor...
Old 08-02-2009, 07:45 PM   #14
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Re: Blower Motor only works on low

Doesn't sound like the typical resistor problem, usually low setting goes out or all but the high, not the reverse. So I second the ground being bad or even the motor not being the best, such as dirty contacts internally. Check the plug to as I have heard of the plug to the blower motor going bad and giving a poor connection.
Old 08-02-2009, 09:25 PM   #15
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Re: Blower Motor only works on low

I have tested the resistor, it is fine. I have swapped all three relays around, they all do the same; so it's not a relay. As I said earlier, it has a brand new motor now. All the wires and connections look fine, and I checked them with a test light. I guess the only thing left is to check the switch in the dash.

So how do I remove the panel that's around the temp controls in the dash, without messing it up or breaking the tabs?
Old 08-02-2009, 09:56 PM   #16
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Re: Blower Motor only works on low

It could be the switch in the dash, but I still wonder if your ground is to blame. To get the dash apart...I was about to tell you, but realized they changed them so I may be wrong. To check the switch, when the blower motor isn't working, check the voltage at the blower fan, it should always have voltage, just different amounts depending on the setting.
Old 08-02-2009, 10:05 PM   #17
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Re: Blower Motor only works on low

You tested the resistor? What did you come up with? Even if it reads it may be off causing the issuie. And again,check all your grounds and connections,lots of grounds come out of that harness.
Old 10-30-2009, 05:46 PM   #18
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Re: Blower Motor only works on low

Shot in the dark here. My fan was blowing on settings 1, 2, and 3 but would completely cut out at 4. After testing the resister pack and swapping in a new user interface board, I found the solution to be a 30A fuse in the engine compartment fuse box labeled "HVAC". Replaced it and it works fine now.
Old 10-30-2009, 05:48 PM   #19
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Re: Blower Motor only works on low

Here's a couple links that may help from far2grumpy.

http://www.s10forum.com/forum/attach...sistor-loc.pdf
http://www.s10forum.com/forum/attach...-hvac-blwr.pdf

Last edited by mich_tech_262; 10-30-2009 at 05:49 PM. Reason: Forgot the links
Old 11-26-2009, 02:58 AM   #20
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Re: Blower Motor only works on low

Ever figure out the problem?

I have the same thing going on in a 1994 S10 Blazer. If you thump the relay (new one or old) with the blower switch on high, it will blow high. Once you switch off of high and try placing on high again, you have to tap the relay to get high blower speed
Old 11-26-2009, 11:16 AM   #21
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Re: Blower Motor only works on low

Quote: Originally Posted by Turbo302
Ever figure out the problem?

I have the same thing going on in a 1994 S10 Blazer. If you thump the relay (new one or old) with the blower switch on high, it will blow high. Once you switch off of high and try placing on high again, you have to tap the relay to get high blower speed

I've been lazy. I'm convinced it's the switch in the dash now, just haven't made the effort to change it out. I took the relay loose from it's rack and let it sit on the intake. That way If I have the fan set on high-heat, it kicks on pretty quickly just from the relay vibrating on the intake . Yeah, it's a hillbilly fix, until i take the time to dig into the dash.
Old 12-01-2009, 08:14 PM   #22
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Re: Blower Motor only works on low

The only thing I can think of is it being your switch like you said. If you've successfuly tested everything you said, thats the only thing left it could be.

Time to go to junkyard.


I attached a wiring diagram for the Heater Circuit. Its blurry (sorry) but you can read it still. It should help you, but like I said i cant see it being anything else.



Good luck
Brandon

Last edited by basketball_00011; 12-01-2009 at 08:17 PM.
Old 12-02-2009, 12:21 AM   #23
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Re: Blower Motor only works on low

Quote: Originally Posted by jtcfanof3
See it in this pic?:

I know,its hard to see past the LS motor!
i see what u did there
Old 12-02-2009, 12:46 PM   #24
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Re: Blower Motor only works on low

Mine did the same thing and it was the relay on the firewall by the blower box. The plug had melted some causing the plug to warp if I messed with it I could get it to work. So I put a new plug in and it's been good ever since. Pull the relay and look at the plug.
Old 12-04-2009, 11:06 AM   #25
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Re: Blower Motor only works on low

I think that i posted instead of a quick reply , any way he goes.
i have a 2001 extreme blower only works on 3 & 4 . what do you think that problem is ?

Thanks, BOWTIEONE
Old 03-13-2014, 07:42 PM   #26
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Re: Blower Motor only works on low

would it blow the blower, resistor, or panel switch to leave the heater on speed 4 while 4 doesn't work? This being so you can wiggle the wires to check for connectivity issues.
Old 03-13-2014, 07:46 PM   #27
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Re: Blower Motor only works on low

I have a 2000 Chevy S10 and i experienced the same problem as SD44 did with no speed 4. Replaced the blower and the resistor and still had the same problem with fan speed 1,2 and 3 working, but not speed 4. I discovered that the 30 amp fuse under the hood stopped speed 4 from working. Thank you mich_tech_262 for the info.
Old 06-12-2014, 03:44 PM   #28
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Re: Blower Motor only works on low

Update: my blower stopped suddenly a few weeks ago. The relay @ the firewall was replaced, but it still required tapping it to get the fan to kick on. Then the blower motor was replaced and it solved the issue completely. i put the original relay back in, but it would not work at all so it was definitely dead, however the motor was also tired.
Old 10-21-2014, 05:25 PM   #29
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Re: Blower Motor only works on low

I just want to say you guys are awesome. My issue started as fan speed 1 and 4 not working, I changed my resistor and ended up with 1,2,3 working and 4 dead. I came here, checked my hvac 30A fuse and sure enough replacing that did the trick! Now all fan speeds work.

Thanks to all the posters!
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