Hi All-

This may be a double problem, but I don't know. Electrical issues are hard to track and figure out what is wrong. Here it goes. So, I replaced my fuse for my 4WD the other day (long story). When I was replacing it, I noticed that the 20amp fuse for HVAC was empty, so I through a spare in it. Few days later, my battery is dead. While I was looking through the manual, I noticed that there are two HVAC fuses, HVAC and HVAC1. My HVAC1 slot had a fuse and was fine. The manual also said that the HVAC fuse was for "manual". I am assuming this refers to manual heating/cooling control. Mine has the automatic climate control. Do I need a fuse in the HVAC slot (sorry, I forget the fuse #)? Would putting a fuse in there some how drain my battery?

Also, is it possible that the blue high beam indicator light being on when the truck is off drain the battery? I don't know why this indicator light comes on when the truck is off, but then disappear when I start the truck. All lights work fine. Somebody mentioned maybe the DRL relay/module. I find it hard to believe that this small LED light would cause a battery to die, but maybe. I wish I new why it came on. It started out sporadic (sometimes it would come on when the truck was shut off but eventually would disappear, lately, it stays on all of the time).

Thanks everybody. This forum is great and when it was down for these last few days, I was lost.

Greg

 

Please put your vehicle information in your signature (via the 'My Profile' link at the top of the page) and attach it to all of your posts when requesting help. It makes it a lot easier on those attempting to help if they don't have to go digging to find out what it is you drive!

From your other posts, I see that you have a '98 Blazer. I'll dig up some schematics and have a look at what you need.

*EDIT* - Here's the schematic for the Blower Motor Control Module which is powered from the HVAC fuse:

The blower motor control module is located near the blower motor under the hood.

 

Oops, sorry about the vehicle description. I changed it now, so we will see if the sign. shows up.


Given that I have the automatic climate control, is this HVAC fuse not necessary given I have a fuse for HVAC1, which appears to be for the automatic control? I will take a look at this wiring schematic, thanks a bunch!

Also, what are your thoughts on the high beam indicator light always being on when the truck is off? Goes away when I start the truck or at the very least, put the key in and turn it past off.

Looking at the wiring diagram, I notice that the HVAC fuse shown (30 A) is for the underhood fuse block. I was referring to the HVAC fuse in the IP fuse block. According to this diagram, the HVAC1 and RDO BATT fuse are the only ones of interest. Does this mean that the HVAC fuse in the IP block really wasn't needed and I probably shouldn't have stuck a fuse in it?

 

The HVAC fuse powers the blower motor control module, so it is necessary for the auto climate control. Was your blower motor working normally with the fuse out???

On the high beam indicator... No clue. I'd have to dig into some schematics to figure that one out. Do these two problems have anything to do with each other (ie. does having the HVAC fuse in cause the high beam indicator to be illuminated with the key off?)?

 

I just edited my previous post regarding teh HVAC fuse, I am referring to the one in the IP block, not the underhood block.

In terms of the blower motor and HVAC controls, everything was working before hand. I just, for no real reason, saw the fuse slot empty so I through one in it. By doing this, did I perhaps complete a circuit that is now drawing battery power at all times?

In terms of the High Beam Indicator, I don't believe it is related to the HVAC fuse at all (does not matter if the HVAC fuse is in or not). It was just a weird problem and I believe one of these two things lead to my dead battery. By the way, I found a schematic for DRL system which shows the high beam indicator as part of this whole schematic. DRL's work, low/high beams work, just this damn blue indicator light being on when the truck is off that is the problem. Thanks

EDIT: So, I jumped the dead battery, it starts running and I keep it running for a while. Also, I have since removed the HVAC fuse that is in the IP block. Suprisingly, all the heating and cooling controls still work (I think my AC is gone), blower works, everything seems fine. This leads me to believe that the HVAC control is not necessary and that the HVAC1 fuse is the real deal. Is it possible that when I had this fuse in this defunct slot, it was drawing current and caused my battery to die?

Also, the High Beam Indicator light is still coming on after I shut the truck off. Takes few seconds, and bingo, it clicks on. Goes away as soon as I turn the key past OFF. I tried removing the DRL relay. High Beam Indicator light is still on, DRL's are disabled, but my driver side high beam doesn't work. Low beams are fine. Put the DRL fuse/relay back in and the driver side high beam works again. Is this common if you disable the DRL by removing the fuse?