3 Heater system questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Hair · 05-28-2009, 07:45 AM

1.0 The heater core has one big tube and one small tube sticking out of the firewall to hook to the hoses. Which way does the heater core go in, is the big tube supposed to be on top or bottom? Does it matter?

2.0 Defrost duct hoses: In LMC they have "OE type" hoses for around $30 and then they have hoses for around $15... I guess they're not "OE style". My question is; what is the difference in these ducting hoses? Are the $15 ones better? rubber? don't fit well? come in one piece and I'll have to cut them to length? what is different about them? Why are they $15 cheaper? Anyone know anything about the cheaper ones?

3.0 [B]Heater resistor[B]: What does this thing do? Does it go bad often? How can I tell if it is bad? I cleaned mine up and blew it off and it looks great. I'm putting the heater box back in and was wondering if I should bother with replacing it or not.

garryk · 05-28-2009, 08:28 AM

02. Don't get the cheap duct hoses, you will regret it. They are aweful, been there, done that.

Hair · 05-28-2009, 09:11 AM

Thanks garryk

Now guys, what about number 1 and 2?

BLACK AND BLUE 67-72 · 05-28-2009, 09:42 AM

No.1 It does not matter, I put the small on top and large one on bottom.

No.2 Get the OE style hoses, the other kind are like a plastic that will not fit very well.

No.3 Resistor controls blower speeds, low med and high, if it goes bad you may only have 1 or 2 speeds, usually low and high or sometimes low and med.

**425HP409** · 05-28-2009, 10:18 AM

It does matter which way you put the heater core in the case. The coolant needs to flow from the bottom to the top to push the air out and enable complete filling of the core for maximum heat and no air locking in the core. The small hose is the inlet bringing coolant from the top of the engine and the large hose is the return. Therefore, the small hose is always on the bottom and the large hose is always on the top. All cars and trucks are like this. The only time it does not matter is if the hoses are side by side.
If the resistor looks OK, that is no burnt coils or connections, it is probably OK.
Charles

Hair · 05-28-2009, 01:11 PM

Quote:

Originally Posted by 425HP409

Therefore, the small hose is always on the bottom and the large hose is always on the top.

Darn it!! How come everytime there's a 50/50 chance that I could get something right, I get it wrong 100% of the time?

Now I'm going to take the core back out of the box and flip it over to where the small tube is on bottom to make sure that everything works correctly.

Its aggravating to get those little brackets to align with the holes in the side of the box and get the screws in.

Thanks for the help.

BLACK AND BLUE 67-72 · 05-28-2009, 01:21 PM

I'm telling ya it WILL work just fine!!!!!! Mine has been like this for 6 yrs. now and it has not had a single problem, the heater will run you out of the cab on even the coldest days!!!!!

also these old systems didn't have the air problems like the newer ones do, like the chryslers that have to have a special air bleeder!!!!

Hair · 05-28-2009, 01:48 PM

Black and Blue I agree with you and I think that it probably WILL work just fine, also, it looks better because your hoses are not crossed.
However, since I have it all out and on the bench I'm going to do it properly. I've looked at some pictures of others and they have the small hose running to the bottom as it should be too, so I'm pretty sure that the small hose to the bottom is the correct way to do it.

Longhorn Man · 05-29-2009, 12:06 AM

Quote:

Originally Posted by BLACK AND BLUE 67-72

No.1 It does not matter, I put the small on top and large one on bottom.

No.2 Get the OE style hoses, the other kind are like a plastic that will not fit very well.

No.3 Resistor controls blower speeds, low med and high, if it goes bad you may only have 1 or 2 speeds, usually low and high or sometimes low and med.

I agree 100000%

jim zag · 05-29-2009, 05:51 AM

Mine works good too even with the hole in the floor next to my rusty rocker panel!!!!

UltraBlue71 · 05-29-2009, 09:46 AM

Quote:

Originally Posted by Hair

Darn it!! How come everytime there's a 50/50 chance that I could get something right, I get it wrong 100% of the time?

Now I'm going to take the core back out of the box and flip it over to where the small tube is on bottom to make sure that everything works correctly.

Its aggravating to get those little brackets to align with the holes in the side of the box and get the screws in.

Thanks for the help.

That is Murphy rearing his ugly head!

PanelDeland · 05-29-2009, 04:57 PM

I turned mine so the hoses didn't have to cross.Small things like that just seem to clean up the engine compartment(not that mine is that clean and neat yet).

05-28-2009, 07:45 AM	#1
Hair Registered User Join Date: Mar 2008 Location: Tullahoma, TN Posts: 406	3 Heater system questions 1.0 The heater core has one big tube and one small tube sticking out of the firewall to hook to the hoses. Which way does the heater core go in, is the big tube supposed to be on top or bottom? Does it matter? 2.0 Defrost duct hoses: In LMC they have "OE type" hoses for around $30 and then they have hoses for around $15... I guess they're not "OE style". My question is; what is the difference in these ducting hoses? Are the $15 ones better? rubber? don't fit well? come in one piece and I'll have to cut them to length? what is different about them? Why are they $15 cheaper? Anyone know anything about the cheaper ones? 3.0 [B]Heater resistor[B]: What does this thing do? Does it go bad often? How can I tell if it is bad? I cleaned mine up and blew it off and it looks great. I'm putting the heater box back in and was wondering if I should bother with replacing it or not.

05-28-2009, 08:28 AM	#2
garryk Registered User Join Date: Feb 2009 Location: Harrisonville, MO Posts: 73	Re: 3 Heater system questions 02. Don't get the cheap duct hoses, you will regret it. They are aweful, been there, done that. __________________ Garry 1968 LWB C20 1969 Blazer 1972 Suburban 1989 Suburban (Beast)

05-28-2009, 09:11 AM	#3
Hair Registered User Join Date: Mar 2008 Location: Tullahoma, TN Posts: 406	Re: 3 Heater system questions Thanks garryk Now guys, what about number 1 and 2?

05-28-2009, 09:42 AM	#4
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: 3 Heater system questions No.1 It does not matter, I put the small on top and large one on bottom. No.2 Get the OE style hoses, the other kind are like a plastic that will not fit very well. No.3 Resistor controls blower speeds, low med and high, if it goes bad you may only have 1 or 2 speeds, usually low and high or sometimes low and med. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

05-28-2009, 10:18 AM	#5
425HP409 425hp409 Join Date: Oct 2008 Location: Prosper Texas Posts: 841	Re: 3 Heater system questions It does matter which way you put the heater core in the case. The coolant needs to flow from the bottom to the top to push the air out and enable complete filling of the core for maximum heat and no air locking in the core. The small hose is the inlet bringing coolant from the top of the engine and the large hose is the return. Therefore, the small hose is always on the bottom and the large hose is always on the top. All cars and trucks are like this. The only time it does not matter is if the hoses are side by side. If the resistor looks OK, that is no burnt coils or connections, it is probably OK. Charles Last edited by 425HP409; 05-28-2009 at 10:19 AM.

05-28-2009, 01:21 PM	#7
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: 3 Heater system questions I'm telling ya it WILL work just fine!!!!!! Mine has been like this for 6 yrs. now and it has not had a single problem, the heater will run you out of the cab on even the coldest days!!!!! also these old systems didn't have the air problems like the newer ones do, like the chryslers that have to have a special air bleeder!!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA Last edited by BLACK AND BLUE 67-72; 05-28-2009 at 01:23 PM.

05-28-2009, 01:48 PM	#8
Hair Registered User Join Date: Mar 2008 Location: Tullahoma, TN Posts: 406	Re: 3 Heater system questions Black and Blue I agree with you and I think that it probably WILL work just fine, also, it looks better because your hoses are not crossed. However, since I have it all out and on the bench I'm going to do it properly. I've looked at some pictures of others and they have the small hose running to the bottom as it should be too, so I'm pretty sure that the small hose to the bottom is the correct way to do it.

05-29-2009, 05:51 AM	#10
jim zag ENGINE BUILDER Join Date: Apr 2006 Location: Shortsville n.y. Posts: 344	Re: 3 Heater system questions Mine works good too even with the hole in the floor next to my rusty rocker panel!!!! __________________ JIM ZAG

05-29-2009, 04:57 PM	#12
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: 3 Heater system questions I turned mine so the hoses didn't have to cross.Small things like that just seem to clean up the engine compartment(not that mine is that clean and neat yet). __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"



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