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Burning Main Fuses

Marty, those two 30 amp fuses in the rear of the box are for the two studs with all the wires attached. all of that is aftermarket additions on those studs. the blower should only draw about 25 amps at full speed. anything over that and it will burn out the resistor pack for the lower speeds and possibly the blower switch. sadly GM only used a single relay for the high speed on the newer rigs. my 93 has a relay for each speed saving all the wiring and switches from factory. IDK why they stopped doing that other than to pinch pennies.

I learned that even with a new blower, if there is too much resistance with it sucking or pushing air in the box that will increase the amperage drawn. I would vote for a new motor, but also check the evap coils and the recirc door while you have to blower out of the hole. you can actuate the recirc door with the motor out and disconnected with just the key on and pushing the max button. it's hard to see in there on the evap but can weasel your hand in there and feel around for debris. use the blow gun on the compressor in there to blow out the evap coil. it's common for the blower to suck in leaves and debris with the heat or defrost running. all that air comes from under the wiper cowl.
 
dbrannon79 said:
Marty, those two 30 amp fuses in the rear of the box are for the two studs with all the wires attached. all of that is aftermarket additions on those studs. the blower should only draw about 25 amps at full speed. anything over that and it will burn out the resistor pack for the lower speeds and possibly the blower switch. sadly GM only used a single relay for the high speed on the newer rigs. my 93 has a relay for each speed saving all the wiring and switches from factory. IDK why they stopped doing that other than to pinch pennies.

I learned that even with a new blower, if there is too much resistance with it sucking or pushing air in the box that will increase the amperage drawn. I would vote for a new motor, but also check the evap coils and the recirc door while you have to blower out of the hole. you can actuate the recirc door with the motor out and disconnected with just the key on and pushing the max button. it's hard to see in there on the evap but can weasel your hand in there and feel around for debris. use the blow gun on the compressor in there to blow out the evap coil. it's common for the blower to suck in leaves and debris with the heat or defrost running. all that air comes from under the wiper cowl.
Click to expand...
That I shall do.
Seeing that the blower high speed is on that 50 amp fused relay circuit, I’m thinking that maybe the plug/harness on the back of the speed control switch may have some burned insulation and possibly some cross wiring happening.
But I also think that even the high blower speed 50 amp circuit is still possibly fed through the lower speed circuits.
The wiring diagram in my book just shows thise wires, and many others, all going into one block, rectangle image, on the page.
 
Anyhow, NAPA got the wrong blower so proper one will be here today, Wednesday, in the morning shipment from Billings.
When I called NAPA a week or so ago, counter man told me it was not listed in their catalogue, okay so I hung up.
Monday I calked the Chevy dealer, he had two possible part numbers, NAPA man looked them up, one was the okd single terminal, other newer one didnt look right but still had the dual spade terminal except on the end of wires instead of out of the motor prompt. Figured okay, change in design. WRONG 🫣😹😹😹
 
And so, the SAGA continues.
Can not find an exact replacement blower motor for this truck.
The motors that fits the flange is a single male spade connector.
I have scrounged the internet with the GM original parts numbers and the single male spade motor comes the closest.
I do not enjoy hacking into original wire harnesses. But here goes.
Clip the two wires back from the terminal, staggered, then splice into the power feed line and install one of the OE female spade type terminals.
Use that spare ground wire for the ground on the new motor.
See how that goes.
 
MrMarty51 said:
And so, the SAGA continues.
Can not find an exact replacement blower motor for this truck.
The motors that fits the flange is a single male spade connector.
I have scrounged the internet with the GM original parts numbers and the single male spade motor comes the closest.
I do not enjoy hacking into original wire harnesses. But here goes.
Clip the two wires back from the terminal, staggered, then splice into the power feed line and install one of the OE female spade type terminals.
Use that spare ground wire for the ground on the new motor.
See how that goes.
Click to expand...
I thought they all were very close to the same as far as the mounting flange and the fan
And the only difference being one ohet pin or a hot and ground

I guess I was way wrong on that
 
dbrannon79 said:
Wonder if someone modified it with an aftermarket "High output" blower motor.
Click to expand...
The two pin harness connector appears to be bone stock.
I did see one blower motor that was the same, on ebay. They calked it an obsolete complete part or some such, way over priced.
I have not yet done anything to my harness, today after I get up and rolling I will do that, modify to the one connector but I’ll not reattach the ground wire from the plug. I’ll use that newly installed grounding wire thats hooked direct to the grounding lug.
Okay, time to trundle oft to bed. 😹👍
 
This is the only other thing that i have for corrosion and oxidation.
IMG_8037.jpeg
I used this on the aluminum wire coming from the main pole into the breaker box of my house.
It stated that it improves conductivity. For wire connections and aluminum conduit joints.
Anyone think this is good in vehicle wiring ?
 
Motor vent hose was not right, thought if it was shortened a little it might fit but nope, elbow to motor was too short.
Left it off.
The motor insulated cover sort of blows that direction so guess thats what it has to be.
Could pull that cover again and try fitting something to make it right, if its really a necessary item. 🤷🏼
 
Next time your out near a pick n pull yard, look for most any 95-99 gmt400 it will have that rubber 90 deg hose. that is for air from the blower to go back into the motor and keep it cool. without it there will be a hole where air leaks out. can't say if the motor would over heat, but if anything plug the hole with something to force all air into the evap.
 
dbrannon79 said:
Next time your out near a pick n pull yard, look for most any 95-99 gmt400 it will have that rubber 90 deg hose. that is for air from the blower to go back into the motor and keep it cool. without it there will be a hole where air leaks out. can't say if the motor would over heat, but if anything plug the hole with something to force all air into the evap.
Click to expand...
The hose that currently was on the heater would in no way make connection with the heater motor. Tried in two different positions then finally settled on the position that puts the spade terminal at the proper top location.
I forgot, totally spaced out about taking motor temperature readings.
Assembled the entire unit. I’ll pull it back down, see about getting that motor vent hose connected then reinstall the ECM and run the motor and get the temp readings.
 
MrMarty51 said:
This is the only other thing that i have for corrosion and oxidation.
View attachment 100083
I used this on the aluminum wire coming from the main pole into the breaker box of my house.
It stated that it improves conductivity. For wire connections and aluminum conduit joints.
Anyone think this is good in vehicle wiring ?
Click to expand...
I've used that and similar products. Anything to keep the air from getting to things. If you don't have a super tight fit on connectors, it could interfere with connectivity.
But with a good connection, I see no problem. Especially on instances where you make the connection and then slather the outside to keep the air out.
I've also used Kopper Koat and Copper Neverseize
 
After I got home from my sisters, truck had been running for over an hour, ambient temp about 100*F. The blower motor had been on high the entire time, and, the AC button engaged.
The main 30 amp fuse was on about 180*F.
The fuse box, where the fuse plugs into was running about 195*F.
I dont think that the main fuse would burn out at that 180* but I am wondering if there is a problem with wiring under that box/panel ?
Am I just over thinking all of this ? ? ? ?
Could someone that has a similar truck with the same under hood fuse box, that also has an IR thermometer, also run similar test and see what their fuse, and where the fuse plugs into, temps is running at ?
That would be a big help.
 
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