Replaced almost every heater component. Cab is blistering hot now

[Mister-B]

My truck didn't even come with a heater core. Bought a new one and installed it along with all new hoses, radiator hoses, and radiator fluid, only to find that my blower motor bearings were going out, and it was making a huge racket and wasn't blowing at full speed. Then, the face to the heater control snapped off at the rivets, and I couldn't control it very well. Found a nice replacement at the junk yard for $19. Then, it was time to change the blower motor. Found a brand new one at Autozone for $21. Got that installed, and here's where the bazaar thing starts...

Turned on the blower, and it's really blowing hard. Turn it off, shut the hood, and take it for a spin. As I'm ready to back out, the heat stops blowing! I'm like WTF! I park, and look at the fuse panel. Sure enough, the fuse blew. Here's the weird part. It calls for a 25 amp fuse, but the PO installed a 10 amp fuse! No wonder it blew. And, it only lasted this long, because the old motor was almost shot and couldn't blow at full speed. I buy the correct fuse, install it, and all is well. Very hot!
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[ol_skool_chevy]

I'm lead to beleive the Heater cores get blocking in then from time to time. I might have to take mine out and flush it or replace it also....
It does not leak but its not real hot either.....

[Kurt L]

hey ol skool try reversing your heater hoses to use the other side of your heater core. had the same problem a few years ago wasn't getting very hot. and old mechanic told bout changing the flow of the water to the core worked great for me.

[ol_skool_chevy]

Originally Posted by Kurt L

hey ol skool try reversing your heater hoses to use the other side of your heater core. had the same problem a few years ago wasn't getting very hot. and old mechanic told bout changing the flow of the water to the core worked great for me.

Oh great.........I just went out and ripped my Whole heater apart Pulled the core out flushed it in the shop...and rebuilt my whole heater...I wish I had thought about that...
Oh well.....

[Stocker]

ol_skool_chevy -- Dunno about your heater hoses, but mine are different sizes so are not made to be reversed. Reversing the hoses would only reverse-flush the core anyway, and you already flushed out your core so it should be good.

The hot water needs to flow into the core at the lower nipple, and out at the upper nipple. Not only because heat rises, but also to help purge air from the system. If your core is good and the rest of the system is up to snuff, you'll have good heat.

[ol_skool_chevy]

Originally Posted by Stocker

ol_skool_chevy -- Dunno about your heater hoses, but mine are different sizes so are not made to be reversed. Reversing the hoses would only reverse-flush the core anyway, and you already flushed out your core so it should be good.

The hot water needs to flow into the core at the lower nipple, and out at the upper nipple. Not only because heat rises, but also to help purge air from the system. If your core is good and the rest of the system is up to snuff, you'll have good heat.

I took mine out just to turn it up side down,,,it had some crap in it that would not flush out...
its HOT now

[SS Tim]

Originally Posted by Mister-B

...and look at the fuse panel. Sure enough, the fuse blew. Here's the weird part. It calls for a 25 amp fuse, but the PO installed a 10 amp fuse! No wonder it blew. And, it only lasted this long, because the old motor was almost shot and couldn't blow at full speed. I buy the correct fuse, install it, and all is well. Very hot!

Might still have a problem. The heater only trucks use a 10A fuse but A/C trucks use a 25A in the same location. If you look closely you can see HEAT below the corner fuse with 10A sometimes with an arrow at the end. Above the same fuse is AIR COND. with 25A and an arrow as well indication the dual useage. Have you inspected or tested the resistor for the blower motor? Blower Motors tend to short as they die not use less power.

[Mister-B]

Originally Posted by SS Tim

Might still have a problem. The heater only trucks use a 10A fuse but A/C trucks use a 25A in the same location. If you look closely you can see HEAT below the corner fuse with 10A sometimes with an arrow at the end. Above the same fuse is AIR COND. with 25A and an arrow as well indication the dual useage. Have you inspected or tested the resistor for the blower motor? Blower Motors tend to short as they die not use less power.

The fuse that blew, was actually the AC 25 amp fuse. I was a bit confused, seeing as I don't have AC, but when I replaced it, everything worked again, and stayed working at full power for a long drive. I wonder if maybe both the AC and heater fuses have a role in the heater.

Also, this new blower blows out MUCH harder then the old one. When I first turned it on, I actually got leaves and debris blow out that the other blower didn't blow through
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[SS Tim]

Originally Posted by Mister-B

The fuse that blew, was actually the AC 25 amp fuse. I was a bit confused, seeing as I don't have AC, but when I replaced it, everything worked again, and stayed working at full power for a long drive. I wonder if maybe both the AC and heater fuses have a role in the heater.

Also, this new blower blows out MUCH harder then the old one. When I first turned it on, I actually got leaves and debris blow out that the other blower didn't blow through
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Not sure how to be much clearer there is only one fuse and it goes in the corner position. It is to be either a 10A or a 25A fuse. As to the motor from what I understand the A/C and non-A/C motors interchange and may have the same aftermarket service part number. Might actually be the A/C intended blower that you have and from what I read it works very well used this way.
If you have an ammeter it would be interesting to see how much that motor is drawing. Your old dying motor could have weakend the fuse through repeated thermal events to a point that the new motor overloaded it.

[Mister-B]

Originally Posted by SS Tim

Not sure how to be much clearer there is only one fuse and it goes in the corner position. It is to be either a 10A or a 25A fuse. As to the motor from what I understand the A/C and non-A/C motors interchange and may have the same aftermarket service part number. Might actually be the A/C intended blower that you have and from what I read it works very well used this way.
If you have an ammeter it would be interesting to see how much that motor is drawing. Your old dying motor could have weakend the fuse through repeated thermal events to a point that the new motor overloaded it.

The 25 amp AC slot is the one that blew. The PO had a 10 amp fuse in it by mistake. The 10 amp heater slot has a 10 amp fuse, which never blew and is still there. Once I removed the blown 10 amp fuse from the AC slot, and replaced it with a 25 amp fuse, everything worked like a charm and still does

This new motor IS a bit longer. I only noticed, because getting the hood bracket back on was more difficult, and I had to use a different wrench because the other wrench I used to get the hinge off didn't fit anymore
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[Katrina/10]

Originally Posted by SS Tim

Might still have a problem. The heater only trucks use a 10A fuse but A/C trucks use a 25A in the same location. If you look closely you can see HEAT below the corner fuse with 10A sometimes with an arrow at the end. Above the same fuse is AIR COND. with 25A and an arrow as well indication the dual useage. Have you inspected or tested the resistor for the blower motor? Blower Motors tend to short as they die not use less power.

I learn something new here every day, always wondered why that fuse had two amp values!

[clemsonteg]

Good info. I noticed my heater sucks in my truck, it gets lukewarm if I sit at idle, but it cools off as I drive. Both hoses going into the heater core get hot, must be plugged up on the inside or just need to be replaced. Gotta love the internet!

[Tinsmith9]

Mr B, I have a heater only set up and my blower is very weak too. Did you already have a part # for the blower motor when you went into Autozone or did you tell them your set-up and they fixed you up? I may just take out my heater core and see what comes out of it with a flush job. Congrats on the fix and thanks all of you who have contributed.

Dan

[Mister-B]

Originally Posted by Tinsmith9

Mr B, I have a heater only set up and my blower is very weak too. Did you already have a part # for the blower motor when you went into Autozone or did you tell them your set-up and they fixed you up? I may just take out my heater core and see what comes out of it with a flush job. Congrats on the fix and thanks all of you who have contributed.

Dan

I don't have a part number. I just called them, gave them the usual make, model, year, engine size. They ordered it. Took about 2 days to come in. No charge to shipping. Total cost, about $21
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[special-K]

Heck,I have driven these trucks forever and it's rare that I ever use the fan or put the controls past 1/2 way. I never wear a jacket in the truck,either. These things have killer heat and the only time I use the fan is to defrost/de-ice or drive with my window open when it's cold. I'd run a 10 fuse if you don't have A/C.

[Mister-B]

Originally Posted by special-K

Heck,I have driven these trucks forever and it's rare that I ever use the fan or put the controls past 1/2 way. I never wear a jacket in the truck,either. These things have killer heat and the only time I use the fan is to defrost/de-ice or drive with my window open when it's cold. I'd run a 10 fuse if you don't have A/C.

Well, if you have a 118 lb gal riding shotgun in the middle bench right next to you, that blower motor becomes VERY important lol
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[Mister-B]

Originally Posted by special-K

Heck,I have driven these trucks forever and it's rare that I ever use the fan or put the controls past 1/2 way. I never wear a jacket in the truck,either. These things have killer heat and the only time I use the fan is to defrost/de-ice or drive with my window open when it's cold. I'd run a 10 fuse if you don't have A/C.

Oh, and I am running a 10 fuse in the "heater" spot on the panel. It never blew. It's the AC one that had a 10 amp fuse in it, and should have been a 25. That's the one that blew, and when I replaced it everything worked perfectly and stayed working
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[SS Tim]

Originally Posted by Mister-B

Oh, and I am running a 10 fuse in the "heater" spot on the panel. It never blew. It's the AC one that had a 10 amp fuse in it, and should have been a 25. That's the one that blew, and when I replaced it everything worked perfectly and stayed working
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What you are calling a heater fuse is likely the radio fuse and should be 3A. Hope this picture helps clarify the fuse IDs.

Like Special-K said you should keep the fuse down to a 10A unless the motor draws about that then it might need to be stepped up some. The 25A fuse that replaces the 10A is also powering the compressor clutch circuit as well in a A/C (C60) equipped truck.

[Mister-B]

Originally Posted by SS Tim

What you are calling a heater fuse is likely the radio fuse and should be 3A. Hope this picture helps clarify the fuse IDs.

Like Special-K said you should keep the fuse down to a 10A unless the motor draws about that then it might need to be stepped up some. The 25A fuse that replaces the 10A is also powering the compressor clutch circuit as well in a A/C (C60) equipped truck.

Ok. The one you have the arrow pointing to, is the one that blew when I turned on the new blower. There was a 10 amp in it. I changed it to 25, and all is well.

The one right below it was never touched or blown. I assume it was a 10 amp, but I guess I don't know 100%, since I didn't have to change it
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[WadmalawJoe]

Originally Posted by SS Tim

What you are calling a heater fuse is likely the radio fuse and should be 3A. Hope this picture helps clarify the fuse IDs.

Like Special-K said you should keep the fuse down to a 10A unless the motor draws about that then it might need to be stepped up some. The 25A fuse that replaces the 10A is also powering the compressor clutch circuit as well in a A/C (C60) equipped truck.

I don't think Mister B is picking up what you are putting down
He should try a 10 amp again since he only has a heater system and not an A/C system. If it blows another 10 amp fuse then is his new blower fan pulling to much juice?

[special-K]

Originally Posted by WadmalawJoe

I don't think Mister B is picking up what you are putting down
He should try a 10 amp again since he only has a heater system and not an A/C system. If it blows another 10 amp fuse then is his new blower fan pulling to much juice?

Yes,or some other issue,like a short. It's like this: There is one fuse location for heat. If you have the A/C system you run a 25A and if you have a non-A/C system you run a 10A. If you run a higher amp fuse than called for you are unprotected at the amperage the unit is designed to operate within. Putting a higher amp fuse in can prevent blowing the fuse but negates the purpose of the fuse as a safeguard against burning something up

[PanelDeland]

Just aheads up.Some of the newer heater cores use a smaller diameter tube,I have to unhook the one in my Dakota about every 2-3 years and flush it both ways with the hose.Otherwise it tends to clog and not heat well.These have a larger tube but probably still would slow over time.

[Tinsmith9]

I remeber the heaters being real strong back on the farm in the 60's and 70's also, so it's something I need to look into. I think I've gotten enough info from this discussion to take it on when I get a chance. Thanks everyone.

Dan

[special-K]

Just trying to help,not pick this thread apart. If you know your new longer motor requires 25a you are fine. If you are assuming based on the larger size,you could be asking for trouble. I'm pretty sure (disclaimer) you never stated you know in fact that the replacement motor is 25a. The OEM system for A/C is 25a (2.5x larger than non-A/C) because you are running more components on that circuit,like a compressor,when the A/C is running. I'm doubtful any blower motor in this realm would draw that much alone. I could be wrong. Just hoping we don't see an electrical meltdown thread in the future

[Mister-B]

Originally Posted by special-K

Just trying to help,not pick this thread apart. If you know your new longer motor requires 25a you are fine. If you are assuming based on the larger size,you could be asking for trouble. I'm pretty sure (disclaimer) you never stated you know in fact that the replacement motor is 25a. The OEM system for A/C is 25a (2.5x larger than non-A/C) because you are running more components on that circuit,like a compressor,when the A/C is running. I'm doubtful any blower motor in this realm would draw that much alone. I could be wrong. Just hoping we don't see an electrical meltdown thread in the future

Thanks. I appreciate that. No, I don't know for sure that the new motor specifically asks for a 25 amp fuse. What I do know, is that it is a bigger motor, and that it blows quite a bit harder than the old one. I know that it had a 10 amp fuse in the heater/AC slot, and that it blew a couple minutes after I installed the new motor. When I switched it to a 25 amp fuse, everything has worked fine.

So, that being said, how would I go about verifying that there isn't some other type of issue? I don't want a meltdown, and would like to avoid it, but at the same time, this fuse box does allow for both 10 and 25 amp... The difference being whether the truck has AC or not, so maybe this is within an acceptable range still. Also, I checked Brothers just now, and they show the blower motor is the same, whether the truck has AC or not. http://www.brotherstrucks.com/prodin...number=HTRM072 it seems like if the blower motor is the same, regardless, that using a 25 amp fuse (which that spot is rated for) would be fine, but I'm open to opinion here, and would appreciate any direction
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