HVAC blower gone wild!

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s10 again
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HVAC blower gone wild!

Post by s10 again »

Ok guys As most know I just got my CC and now I'm having a problem with my HVAC blower. The last couple of days my blower motor has been randomly changing in speed. I originally thought I was having an ALT. problem. But I narrowed it down to only happening in the #3 fan position only so I started thinking that it was the speed control resister board.

Well tonight leaving my kids open house school thing I had no blower at all for a couple of miles then it just started working again. There is what looks to be a new AC/delco fan relay in the glove box. I might try putting it in but I'm still thinking about the resistor board being the culprit. But would it kill the blower at all speeds then get jarred and start working again?

Thanks in advance.

Chris.
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HenryJ
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Post by HenryJ »

Check your high speed fan relay.

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Post by s10 again »

I think that is what is in the glove box so I'll go ahead and swap it in. Now where is that thing hiding at in our trucks?

Thanks!!!

Chris.
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Post by HenryJ »

ZR5OnIt wrote:FYI, I just found out the #9 fuse on the side of the dash controls power to the blower fan switch at all positions, but the HVAC fuse under the hood (to the left of the hazard lamp fuse) controls the 4 (high) position only. So, if the #9 is out, no fan at all, but if the underhood HVAC fuse is out, 1, 2 & 3 will work but not #4. Weird, but true. :wink:

"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving!
- ThunderII KE7CSK
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Post by s10 again »

I read that one when I did a search. But my blower will work on 1,2 and 4 fine but on 3 the blower acts like it is getting varying voltage. Then last night we lost the blower at all speeds for a bit and then it started working again within a couple of miles. But still surges when the switch is on #3 only. I have not had the chance yet to find where that hi speed relay goes to swap it out any ideas?

I just got the stuff the flush the cooling system so I hope to spend some time working on it this eve if the rain stops. Why oh why do we have a 2 car garage with everything in it but room for our cars. :crazy:


Chris
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Post by HenryJ »

If your problem is with a middle setting , then it is the resistor or the control head.

"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving!
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read the thread, now I need an answer

Post by davejb851 »

Most times when my blower is set on 1, I feel now air being pushed through. So I use 2 most of the time. Just the other day when I started the truck and drove off, I started to smell that scary burning electrical smell.
I switched the fan to 4, the smell went away. When I went back to 2 everything was fine. The fan slowed down appropriately, there was no return of the smell, and it hasn't happened again.
Is this most likely that resistor/board going bye bye?

And from what I have read here the board and resistor is in the fan housing?
[size=75]I tell my Boy Scouts.....leadership isn't a job, it's an attitude! Lead by example!
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s10 again
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Post by s10 again »

In my case it was the blower motor. I have never seen one fail in this manor kind of strange. It was either a problem with the brushes or the commutator possibly even both. It was not till the blower would not come on till I opened the hood and tapped it was that clear.

I did not have any burning smell but I could see that is a possibility. In your case I would suspect the resister board. It is in the duct under the hood near the blower motor and should be easy to replace for under 20 bucks. It could be that something got hung up on one of those resisters and smoldered off or got blown off from the higher blower speed. I would pull out the resister board and just give it a good look and see if you might need to clean it off.

Chris.