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Blower help...

Avery4jc

Avery4jc

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No funny jokes here, I actually have a problem that is most likely something simple but I can't figure it out. Not one bit of my heating/cooling system works from what I can tell, the p/o claims that he just disconnected the clutch because it was "robbing power" but now it looks like it just doesn't work. I didn't want to overwhelm myself so I decided that I would just start with the basics and get the blower working, the heater, defroster and a/c all use it so it seemed like a logical place to start.

I couldn't get the old motor to do anything but they are so cheap I decided that it would be dumb to waste any time on it and that I'd be better off just buying an entire new blower motor....

I hooked it up but of course it didnt' work, just my luck. So I decided to use that bright red wire in the picture below and clip the alligator clip onto the post on the motor then touch the other end to the positive post on the battery to test and make sure the new motor was working. It spins perfectly and puts out a ton of air when I do that so that was comforting...

So now I have to figure out what isn't working. I put the positive point on my volt meter in the lead going over to the motor and grounded the black lead then flipped on the switch in the cab to all of the positions and I'm not getting anything , I pulled out the dash about two months ago (when this project started) and I cleaned all the connections so I know that they are clean. I also checked the connections in the engine bay and they all seem ok too so somewhere along the line the power isn't getting through.
Then just for safe keeping I pulled the two fuses related to heat/ac/blower motor and they are both perfect so I know power is getting through the fuse box too.

Here is where my knowledge stops though. I did a search and found that sometimes guys lose one or more blower motor positions and the common problem was a resistor (was described as the little "springs") so what I'm thinking is either all of mine are shot or something that I don't know of isn't working. Are those housed in the metal box that I am unpluging in picture three?

So after all that my question to ya'll is what should I try to replace first?

Ok thanks for the help on this long winded post but I know it's easier to help when I tell you everything that I've done.

Oh, and if someone can fill in the blanks on the last picture I'd appreciate it, I don't know what they do or are called.

-Avery

picture 002.jpg

picture 003.jpg

picture 004.jpg

picture 003.5.JPG
 
yep...

The resistor is located in the airbox,held in by two sheet metal screws,and the wires plug onto it.(I see it in one of the pictures)...probably that or the relay at fault,if the fuses are good,and the heater switch works..:crazy:
 
Ok, so the silver box in picture 3 is the resistor box and could very well be the problem. But you mentioned the relay too, where is it located?

My dad has been saying that it was that box from the get go not because he or I know A/C stuff but because when I would flip the switch in the cab he could hear that box clickin' and making some wierd noises.

Ok, I guess I'll just try to find a "resistor box" for an '85 K10 at the parts store and put it on, if it works then great, if not then I'll go from there.

-Avery
 
I can't see your pictures but the "silver box" is most likely the relay. The "blower motor resistor" is mounted directly to the air flow chamber of the HVAC system. It will just look like a flat piece of metal or fiber board, screwed to the HVAC box with three or four wires coming out of it.

If you take out the screws and remove the unit, it will look like springs mounted to the back side of the board. These are the actual resistors that control your fan speed and they are mounted in the air chamber to keep them cool.
 
Yeah, that is exactly what my stuff looks like...

Here, I know your not a member so use this, I just hosted the picture that I was asking people to lablel on my site so you can see it. So the upper bubble is the "blower motor resistors" and the lowest bubble is the relay?

http://avery4jc.googlepages.com/picture003.5.JPG

-Avery
 
Yep. And the middle bubble is your a/c pressure cycling switch.
 
pictures= 1000 words!

The resistor is in picture # 2!..the black thing with 2 screws holding it in,and wires plugged onto it..the "silver box" is the high speed blower relay--if its clicking ,its getting juice..most likely the resistors are burnt..they might be a dealer or junkyard item only--not sure if parts stores sell them..:crazy:
 
Ok, but at least I know what everything is now. I'll try Kragen and Auto Zone and if they don't have it then I guess I'll try going to the local Chevy dealership. <--sounds very very expensive!

So the resistors set the voltage which sets the fan speed but what does the relay box do?

Oh, and yeah diesel your title on post #8 is dead on, Pictures do = 1,000 words which is why almost all of my question threads have pictures and a huge description so that we don't spend days trying to figure out what stuff is. Shoot I even did a video thread to answer some questions a while ago.

-Avery
 
The relay supplies full voltage to the blower, it only comes on when the fan switch is set to high. My switch in the dash was burned up, you may want to check/ replace that also...
 
Bad Karma said:
The relay supplies full voltage to the blower, it only comes on when the fan switch is set to high. My switch in the dash was burned up, you may want to check/ replace that also...
Click to expand...

Ok, I know that I would be able to physically see the resistors when their blown out so I'll check them first. If they look fine then I'll look into the switch.

-Avery
 
I just came inside and long story short it's the relay.

I used a testing light and grounded it on the body. I tested it straight to the battery and it worked. Then I stuck it into the prong coming from the switch in the cab and it had power. Next I stuck the harness partially back on where the resistors are (I took it out first and cleaned the little springs which all look to be in good condition) and then stuck the tip to the output prongs and it light so I know that power is getting to the resistors and out of them.
Next I stuck it in the harness that runs to the relay box and I got a nice bright light so I know that the power is getting to the relay box so I tested the output on the box and got nothing. Just for kicks I stuck the harness that goes to the relay box straight to the post on the blower motor and the first 3 fan settings work which makes sense because you all said that the relay is what puts full power for high.
I'm going to run to the parts store and see if they have a relay box before I go to work. I only work a couple hours tonight so when I get home I'll let you all know how it goes.

Thanks a ton for the help.

-Avery
 
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Ok here's the scoop. I got home from work, scarfed down some Taco Bell and then wen't at it. I replaced that relay (that Auto Zone surprisingly had and knew exactly what it was) and to my great surprise it worked. I've been working to get that stupid blower motor working for about a month now and I finally got it to push some air!

Now the only problem that I can see (at least for the blower motor issue, one step at a time folks) is that it has 1,2,3 but when I put it onto 4 (full blast) it doesn't do anything. The threads that I've searched on regarding blower motors are mostly for this issue and I believe even though my visual inspection said that the coils were fine that is the leading solution for this problem right?

When I'm back at Auto Zone I'll pick up a new resistor pack and replace it for safe keeping, then hopefully it'll work full blast. From here on out I decided to take it to a shop and let them finish making it cold. I figure I got this far and I better let them do their job and pressure test the system then charge her up. Oh, and in 1985 were they using 134a or was it still R12?

OH, I almost forgot while I was at Auto Zone (which seems to be my new favorite place, they are fast and know what I'm talking about with some pretty random parts none the less) I broke down and added a Haynes Repair Manual to my collection and man am I glad I did. This thing is great!

-Avery
 
I don't think high goes through the resistor, that should be straight battery/system voltage. On an AC setup I'm not sure how it's powered though, with the relay in the setup.
 
Yeah I just did some research after I posted that and realzied that hi doesn't go through the resistors (I think somebody mentioned that in the first page too) so I'm sure that it's the head unit in the cab. That is the only thing I haven't replaced and since 1,2 and 3 are working then that must be it.

I love love love this Haynes Repair Manual I just got last night. I'm going to head out today and see if I can get the A/C clutch to start engaging since I have some wiring schematics now.

Hopefully this will bump it for the morning crowd and somebody can have some insight.

-Avery
 
When I had 1,2,3, but not 4 in a different truck ('95 Yukon) the problem was a bad connection (Melted connector) in the "hot" wire coming from the alternator (Different feed than the resistor block). My head unit and relay were fine. I replaced the connector and all was better.

Might be worth checking to make sure the right wires are hot before you put up the $$ for a new head unit.
 
I had forgot about the melted connector issue.

This is SO common on 80's GM cars. I don't know if the trucks use a connector for the heater blower wires between the head unit and the resistor/blower, but if it does, check that out.
 
So between the head unit and where the wire harness plugs into the resistor pack there is another connection? Probably in the dash somewhere.

Big ben, you are saying that since 4 doesn't use a resistor and pulls power straight to the relay and then sends it over the the blower motor the connection from from the battery (or probably fuse box) to the relay could be bad?

I am going to take my wiring schematics out in a little while and see what wire goes where and then try to trace where the highest setting pulls power from, probably just yank out the dash while I'm at it and check those connections.

-Avery
 
dyeager535 said:
I had forgot about the melted connector issue.

This is SO common on 80's GM cars. I don't know if the trucks use a connector for the heater blower wires between the head unit and the resistor/blower, but if it does, check that out.
Click to expand...

My brother's '93 S-10 just fell prey to the melted connector, so I'd say it's still a possible issue here.
 
Where is this notorious connector you guys are talking about? Does it go straight from the unit in the dash to the blower motor?

-Avery
 
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