High speed fan position not working

purdaddy

purdaddy

I ate a big red candle.
Hey guys, I've searched and read thru all the threads I could find on the HVAC blower motor and it's setup, but I'm just not sure any of them apply to the scenario I've got.

My Ty's Heating and A/C work great on all settings, but the fan speed control only works in the first three positions. Runs correctly in Low (Lo) (position one (1) from the left) to medium-high (position three (3) from the left), but blows nothing when set to High (Hi) (furthest right position). Now I understand that the vaccuum switch and relay control the first three settings, but that high is simply full 12v power to the blower motor. My question is, what provides the full 12v power to the blower motor? Where would I look to determine if it's getting it? In essence, what's the path from the switch set on high (Hi) to the blower motor???

Thanks,

-Patrick
 
kentuc

kentuc

Member
Re: High speed fan position not working

Near the blower motor under the hood is a relay for speed control.Change that.About $12.00- $15.00.
 
Jer

Jer

Don't taze me bro!
Re: High speed fan position not working

My heater fan doesn't seem to blow at all but it's an aftermarket (?) non-A/C blower that was installed when I bought it so I'm not sure if it's this relay or what the deal is. Is there a good way to test this before ordering it? Thanks.
 
purdaddy

purdaddy

I ate a big red candle.
Re: High speed fan position not working

kentuc said:
Near the blower motor under the hood is a relay for speed control.Change that.About $12.00- $15.00.
Click to expand...

Does this relay simply switch from A) power regulated by the fan speed control switch to B) full 12v power (bypass or something of the like)?

And which relay is this physically? I'm assuing that you're referring to the one between the blower and the A/C Accumulator. Is that the one? There are at least two others on the firewall (near the middle) as well. Just want to be sure I'm replacing/testing the right one(s).

Thanks again,

-Patrick
 
kentuc

kentuc

Member
Re: High speed fan position not working

yes to your first ?....Yes it`s the shiny one near the blower motor, on the plemnum..
 
Tommyquest

Tommyquest

The Member's Member
Re: High speed fan position not working

Jer said:
My heater fan doesn't seem to blow at all but it's an aftermarket (?) non-A/C blower that was installed when I bought it so I'm not sure if it's this relay or what the deal is. Is there a good way to test this before ordering it? Thanks.
Click to expand...
Is it grounded correctly?
 
Jer

Jer

Don't taze me bro!
Re: High speed fan position not working

Tommyquest said:
Is it grounded correctly?
Click to expand...

Where is the ground for it? There's a wire that's not grounded on the firewall but it's just past the center point towards the brake booster and is a pretty small wire. It's been unbolted since I got it and everything seems to be running alright. What could this wire be? Is there a chance that it's the ground for the heater fan?
 
kentuc

kentuc

Member
Re: High speed fan position not working

Hey Jer, since it`s not a stock fan set up. How about a picture?, The ground for the blower is a #10 wire[almost as big as the wire on the back of the alternator,and it`s black.]
 
purdaddy

purdaddy

I ate a big red candle.
Re: High speed fan position not working

kentuc said:
yes to your first ?....Yes it`s the shiny one near the blower motor, on the plemnum..
Click to expand...

Sweet! Thanks, we'll give that a try tomorrow, assuming I can find the relay locally on a lunch break ;) (thinking I can).
 
purdaddy

purdaddy

I ate a big red candle.
Re: High speed fan position not working

Ok, well....here's something weird.....I go to look at the relay in question, hoping to pull a part number to match it up with the link posted above in this thread and find that the large (12/10? gauge) red wire coming from/into the silver relay between the blower motor and the accumulator is not connected to anything on the firewall side of the wire. It's been cut and taped it appears (see pic).

relay_wiring_02.jpg



Should this be attached to the power junction on the firewall there (also seen in the pic) or is it supposed to be attached to more red wire somewhere?

Wondering if that isn't why I don't have the High speed fan. There's no full 12v power being supplied to one side of the relay. Thoughts???
 
Jer

Jer

Don't taze me bro!
Re: High speed fan position not working

Looks aftermarket. Trace where it goes and my guess is that it used to power an amp or something like that. What ever you do, DO NOT connect it to that location until you verify where it terminates. Doing so could cause a short/fire since that terminal on your firewall is another source for the hot side of your battery and is not switched... just constant 12v.
 
kentuc

kentuc

Member
Re: High speed fan position not working

Use a 30 amp fuse between the red wire and the top terminal on that junction block.Something there in it`s history!!
 
purdaddy

purdaddy

I ate a big red candle.
Re: High speed fan position not working

Jer said:
Looks aftermarket. Trace where it goes and my guess is that it used to power an amp or something like that. What ever you do, DO NOT connect it to that location until you verify where it terminates. Doing so could cause a short/fire since that terminal on your firewall is another source for the hot side of your battery and is not switched... just constant 12v.
Click to expand...

Well, looking aftermarket or not, the connected end of this wire comes directly from the passenger side edge of the silver box topped relay (blower motor relay). Due to that fact, I took some initiative and grabbed a 10 gauge wire with an inline 30amp fuse and tapped it to that power union on the firewall.......lo and behold, the high speed fan kicked on! Yipee!! :tup: It's now disconnected until I'm sure what to do.

Now the question is, is that power union on the firewall (seen in the pic above) where this line was supposed to be connected all along? And why would someone choose to disconnect it and cap it (actually taped)???

Thanks!
 
purdaddy

purdaddy

I ate a big red candle.
Re: High speed fan position not working

kentuc said:
Use a 30 amp fuse between the red wire and the top terminal on that junction block.Something there in it`s history!!
Click to expand...

Man, that's funny.....I was just replying that I tried that (see above)....:tup:

So I'm assuming then that that is where this wire was supposed to be connected.....?
 
supersports10

supersports10

New member
Re: High speed fan position not working

You Have It Right, It Came Disconnected From The Firewall On The Previous Owner, And He Didnt Know What It Was, So He Taped It Off.get Yourself A Ring Terminal And Reconnect It To The Small Junction Block On The Firewall.

Ss
 
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