Jump to content

High Blower Setting Kills Engine

8D3

By 8D3
in Ask A GM Technician

Recommended Posts

8D3 Enthusiast

8D3

Posted
Posted

Hey guys,new to the site.I just picked up a project 1995 Z-71 and I have been messing around with getting stuff working.I have a problem with the blower fan.It works great but when switched to high,the engine acts like it loads up and will die.No problem on any other setting,just high.Could the resistor be bad?

bossier62guy Senior Enthusiast

bossier62guy

Posted
Posted
Hey guys,new to the site.I just picked up a project 1995 Z-71 and I have been messing around with getting stuff working.I have a problem with the blower fan.It works great but when switched to high,the engine acts like it loads up and will die.No problem on any other setting,just high.Could the resistor be bad?

 

I don't think a faulty resistor is causing that condition....maybe a bad blower motor.

8D3 Enthusiast

8D3

Posted
  • Author
Posted

Thats just it,blower runs thru all speeds just fine and the voltage gauge inst eradict?I may swap it with another one just to see.

8D3 Enthusiast

8D3

Posted
  • Author
Posted
Ignition switch

 

That is a possibilty since the steering column has seen better days.But why only on high setting?

minibike132 Senior Enthusiast

minibike132

Posted
Posted
Ignition switch

 

That is a possibilty since the steering column has seen better days.But why only on high setting?

 

 

 

I don't have a diagram for a 95 handy, the earliest thing I have is a 98 and it is going to be different. If this rolled into my bay with your complaint I would pull the diagram for the ignition switch. There is usually only 4 or 5 outputs for everything that is controlled by ignition power (except for new vehicles that don't really have any outputs, it's all bcm signals). So if you only have 4 or 5 outputs that means quite a few things are going to be on each output. If the blower output is on the same output as the fuel pump relay, injectors, pcm, ignition module etc. it could cause what you are explaining.

 

I would get a diagram, see which output is feeding the blower and see what else it feeds, if it's something critical then use a sealed beam to load up that circuit and do some voltage drop tests. If there is a bad contact in there it may be good enough to carry some current but the blower on high might just be enough to rob current from another circuit.

 

Same thing for the ground circuit, if it is shared by something critical and there is a poor ground it will cause the same thing.

 

W body cars were good for this, turn on the headlights and the blower stops working, turn on the blower and the wipers stop working. It was a no brainer for those because it was common. On yours I would do some testing before replacing, but ignition switch is where my testing would probably start, unless the ground is common for something critical and easier to get at.

8D3 Enthusiast

8D3

Posted
  • Author
Posted

How hard is it to change the ignition switch?I replaced the blower resistor since I already had it and it was no help.I did notice that the gear indicator would start flashing too with the blower on high.Im really leaning toward the switch.

minibike132 Senior Enthusiast

minibike132

Posted
Posted

I'll bump ya, it's been a while since I've been under the dash of a 95 so I can't remember what it looks like or how difficult it is. Maybe with the bump someone else that knows will help ya out.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,840
    Total Members
    8,960
    Most Online
    appletrav
    Newest Member
    appletrav
    Joined

  • Who's Online   2 Members, 0 Anonymous, 242 Guests (See full list)

  • Latest Articles

  • Posts

    • newdude
      2 speed transfer case optional now?

      By newdude · Posted

      This is a 1/2 ton thing ONLY.  All HDs 2020-2026 have the two speed transfer case, with Autotrac as an option.     1/2 tons 2019-2026, regular 4x4s come with a single speed case (no 4LO!), and trucks with Z71 ordered, or all Trail Boss trucks come with the 2 speed case.  2 speed case is also an option on WT, and is also standard on High Country.  
    • newdude
      Different requirements for oil filters?

      By newdude · Posted

      2013 5.3 still to this day calls for the PF48 filter.  Which as a 15psi bypass pressure.     There is a TSB, 17-NA-157 that talks about the PF-63 and PF-64 filters which have a higher bypass rating of 22psi.    TSB HERE - temp.xml   "Beginning in 2012, the oil pumps began to regulate main gallery feedback instead of pump out pressure. This means that the oil pump now does not begin to regulate until pressure is built up to the main gallery. This change reduces the amount of time it takes to provide oil to the engine bearing and lifters during extreme cold start conditions.  Main gallery feedback oil pump control systems are present on the following engine families which use Spin-on oil filters: Small Gas Engine (SGE), Large Gas Engine (LGE), High Feature (HFV6) Gen2 and Small Block Gen5 gasoline engines. These engines with the main gallery feedback oil pump control systems are factory built with an ACDelco® oil filters"   It also calls out what engines use those filters.  The gen 4 small blocks were not on that list (LMG, LC9, L9H, L92, L94, L20, L96).  Gen 5 small blocks use the higher pressure filter.          That all said...   Your 7045 Napa filter is the PF63 equivalent, with 22psi bypass.  You are already using the higher bypass pressure filter.  You CAN keep using it, you don't technically have to use it though.  
    • Grumpy Bear
      Different requirements for oil filters?

      By Grumpy Bear · Posted

      Do you know WHY the filter relief setting was increased to 22 psig?    When the new system goes into the second stage the pump volume ramps up considerably. It was found that the 15 psi filter bypass setting put the filter in bypass on a warm engine when the second stage was activated. Raising the filter bypass setting forced the filter to do what it designed to do. Filter. Preventing debris from circulating during high load, high rpm operation.    So next question is how did GM find this out? VLOM/lifter failures and a deep dive by Melling Corp.    Last question. Is it required? Look at it like this; a motor may be equipped with a rev limiter. But it only works if the set point in reached. That 22 psig setting only matters if the pressure differential across the filter media exceeds 15 psig during normal warm operation. Second stage kicks in around 3000-3500 rpm.    I can't answer your question because I don't know you and how you use the truck. But I think there is enough information here to let you decide for yourself. 😉
    • Coastie05
      give me some tips to make my truck look better

      By Coastie05 · Posted

      Go back to OEM wheels. 
    • newdude
      2020 Trailboss 6.2 replacement

      By newdude · Posted

      Probably not their first rodeo, so it should go as planned most likely.  Typically the service manager or tech doing the swap will put some seat time to shake it down after they get it all put back together.  We usually put 50-100mi before we hand them back so if something happens, its not after you get it.  A coolant leaks, oil leaks, a ground left off or loose, vibration, etc.     The new engines so far have been good?  There's been a couple that have popped out there again (the replacement engine) but most have been okay.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...