What did you do with your GMT400 today...or yesterday....

[Big T]

I've been following. I'm one of the members here that rode in his truck.

I rode in it too, but sightings of late are rarer than a Sasquatch.

 

[Paveltolz]

Yes, K1500 S code but that's not an EGR'd Lower. Got rid of that unit (cracked ears too) in 2010.


I found this one in a shop's junk pile in Wendover. Saw bumper holes and pulled in. Owner was swapping in a 454....
Had it cleaned up and coated.

 

[Husker6.5]

Wendover, now that's the middle of nowhere! Only things going for it is the Enola Gay hanger/museum at the old AAF base and when they're running over on the Flats. At least West Wendover has the casinos!

 

[93detroit]

I installed a Bean Diesel fuel sump to feed the AirDog. 1/2" line from tank to IP. Also calibrated tach.

 

[dbrannon79]

My blower fan switch burnt out the other day. only have high fan now. I've been thinking about installing some relays for each speed similar to how the burb's are. I was looking at the schematic comparing the pickup to the burb's. it seems some of the burb's came standard with a relay for each fan speed which would eliminate the load on the fan switch.

BTW: anyone have any clue why GM vehicles always have the blower spin on extreme low as soon as the key is turned on? something I hav always noticed on most older model GM vehicles is as soon as the key is on you can hear the slight movement of the blower spinning very slow, not enough to move any air but still it spins.

 

[ak diesel driver]

I'd be checking the blower motor resistor out first before condemning the switch. Classic symptom is high speed only

 

[dbrannon79]

I'd be checking the blower motor resistor out first before condemning the switch. Classic symptom is high speed only

I will have to check that. I just remembered I have a spare air box in the garage which has a resistor in it. some day I will get to install the box as mine is cracked and sealed with silicone at the moment.

 

[Husker6.5]

Yes, they are notorious for burning out resistors to the fan motor, both on the p/u and burb. And the symptoms are exactly as you described, either losing the lower speeds one at a time, or all at once, so there's High only. I've never encountered the barely turning fan motor phenomenon, sounds like you may have a voltage leakage through a switch or through a fried resistor.

 

[dbrannon79]

out of curiosity, what is the normal current draw for the blower? once I get it up and working on all speeds again I can test the motor to see what kind of amperage its drawing and possibly determine if it's beginning to fail.

The blower fan was replaced about 1-1/2 years ago (auto parts chineesium). When I replaced it, the old one wouldn't spin up randomly where I would keep a long handle screw driver under the seat just to reach over and smack it for it to start working LOL it worked for a while like that until I replaced it and the blower switch that had a crispy pin in the connector.

 

[Husker6.5]

I have no clue on current draw, I've never put an amp clamp around the leads while running. Oh, the other thing the fan motor/wiring is known for is poor grounding connection through the multipin connector that will overheat and melt them. Common fix is a separate, heavier gauge ground wire direct from the motor to the under dash chassis ground stud the dash harnesses all use.

 

[jrsavoie]

I have no clue on current draw, I've never put an amp clamp around the leads while running. Oh, the other thing the fan motor/wiring is known for is poor grounding connection through the multipin connector that will overheat and melt them. Common fix is a separate, heavier gauge ground wire direct from the motor to the under dash chassis ground stud the dash harnesses all use.

I use the dash mount bolt just a few inches to the right of the blower motor

 

[dbrannon79]

yes indeed, I installed a ground wire when I had replaced the fan. the power lead "had" an inline connector further up behind the glove box that had melted too. I had to cut it out and hard wire it

 

[Husker6.5]

I use the dash mount bolt just a few inches to the right of the blower motor

That works too. But by using the same grounding lug up under the dash that the rest of the harnesses use, you eliminate the possibility of creating a "ground loop" that can interfere with sensitive electronics or introduce "noise" into them.

 

[dbrannon79]

well, I pulled out the resistor from the truck last night, that was a chore for my hands! it didn't look burnt at all. I compared it to the one I had in the new / used air box in the garage and was planning to swap it anyway, but the connectors were different. mine has a sealed style connector and the one in the garage (from a 94) has spade terminals. that wasn't going to happen. so I guess I need to order some parts. I suppose I will order both the resistor and the switch so when I attempt to pull it apart again, I will have all the suspect parts handy to replace.

 

[Husker6.5]

It will "look" just fine. You need to check the resistance across each of the lower speed resistors to find the open (burned out) one(s).

And yes, reaching up there to get to the resistor pack out/in is a bugger!

 

[ak diesel driver]

There's also a diode in there that can pop leaving only high speed

 

[dbrannon79]

The diode I didn't check. but if it's bad I will need to replace the complete resistor anyway. ordered both and should arrive tomorrow. I can return the one I don't use. none of the auto parts show a Delco option. only their "house brand" RA shows Standard Motor brand and so does Amazon so for the cheaper price including free one day shipping I choose Amazon for the order.

Ra does show the Delco resistor but I wasn't going to pay more in freight than the cost of the part!

 

[Will L.]

I never understood why GM didn’t just put in a rheostat and be dine with it.

 

[dbrannon79]

that actually wouldn't be hard to do LOL. back in the day I built a "solid state" one making my own high amp DC motor controller out of a couple of mosfets, a transistor and a 555 timer IC connected to a simple volume control knob. it would handle about 200 amps at 12v and hardly build any heat from the electronics.

I might could use this concept to run dual blowers and not even need a blower resistor if I ever decide to attempt a rear AC/Heat adaptation behind the rear seat!

 

[jrsavoie]

The diode I didn't check. but if it's bad I will need to replace the complete resistor anyway. ordered both and should arrive tomorrow. I can return the one I don't use. none of the auto parts show a Delco option. only their "house brand" RA shows Standard Motor brand and so does Amazon so for the cheaper price including free one day shipping I choose Amazon for the order.

Ra does show the Delco resistor but I wasn't going to pay more in freight than the cost of the part!

Did you check Amazon or search the AC Delco part number?