Heater Emergency!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1972GMCsierra4x4 · 12-06-2013, 01:11 AM

So temps finally dropped off to winter here in Kansas and my heater still may as we'll be an air conditioner. Swapped cores, put in all new heater gaskets and nothing has helped even after I let my truck idle and warm up for 10 minutes. Any advice/help would be greatly appreciated

cdowns · 12-06-2013, 08:26 AM

a 190 radiator thermostat and good antifreeze

**Tom Vogel** · 12-06-2013, 09:27 AM

Have you put your hands on the heater hoses to see that they are warm and that the coolant is circulating in there? Is the heater valve opening and closing? And, of course, youve got the radiator topped off and full, right?
That thing should toast you right out of there.

Longhorn 70 · 12-06-2013, 09:36 AM

I'd check the heater valve. BEWARE there are 2 types that look similar. One that opens on vacuum and one that closes on vacuum. I think we want the close on vacuum type.

As Tom said check the heater hoses. Make sure BOTH of them get hot.

1972GMCsierra4x4 · 12-06-2013, 09:46 AM

How hot are we talking? Both get pretty warm after the truck runs a little

1972GMCsierra4x4 · 12-06-2013, 10:06 AM

Hoses, that is

Andy4639 · 12-06-2013, 10:06 AM

Check the cables on the dash unit. Make sure they operate the door for the hot air. Just because they slide back and forth doesn't mean anything. U have to watch and see them working.

Lee H · 12-06-2013, 10:09 AM

My heater will not blow hot air after just idling. It takes being driven a few miles and then it heats up slowly. After 3-4 miles it's really hot.

Mr Chevorlet · 12-06-2013, 10:44 AM

I would say also check to see if the flapper door inside the heater box is open to let the heat from the heater core to blow out.

463 · 12-06-2013, 10:46 AM

Quote:

Originally Posted by Lee H

My heater will not blow hot air after just idling. It takes being driven a few miles and then it heats up slowly. After 3-4 miles it's really hot.

You will have to have a system pressure test to see if there is a leak. in most cases you rad cap is weak. Systems need 15 - 16 lbs psi to work right when it's cold. Start by replacing the rad cap first.

1972GMCsierra4x4 · 12-06-2013, 11:37 AM

Thanks for all of the help guys, I really appreciate it. As it turns out, my radiator wasn't completely full. I topped it off before I went to class this morning and I'm going to burp my coolant system during shop today to get all of the air out (just in case). I'm not sure if my blend door is working right, but I think it is because when I move the lever, the air flow through my floor vent changes. I'll make sure it is when I replace my in-cab gaskets either tonight or this weekend. As for y'all who said to check my heater valves, I forgot to mention that the one of the POs by-passed them and installed straight hoses.

1972GMCsierra4x4 · 12-06-2013, 02:01 PM

One more question. How do you guys have your heater hoses routed? I've got the one from my water pump going to the inlet of my core at the bottom and the top return line going to the radiator. Is this right or wrong? The PO had them routed this way so that's how I did them.

Lee H · 12-06-2013, 02:09 PM

Quote:

Originally Posted by 1972GMCsierra4x4

One more question. How do you guys have your heater hoses routed? I've got the one from my water pump going to the inlet of my core at the bottom and the top return line going to the radiator. Is this right or wrong? The PO had them routed this way so that's how I did them.

OK, that's why you have little heat. A better routing is intake to bottom of heater core, top of heater core to radiator or water pump.

1972GMCsierra4x4 · 12-07-2013, 01:24 AM

Glad to say that my heater works awesome now! Thanks to all who gave advice!

12-06-2013, 01:11 AM	#1
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Heater Emergency!!! So temps finally dropped off to winter here in Kansas and my heater still may as we'll be an air conditioner. Swapped cores, put in all new heater gaskets and nothing has helped even after I let my truck idle and warm up for 10 minutes. Any advice/help would be greatly appreciated

12-06-2013, 08:26 AM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Heater Emergency!!! a 190 radiator thermostat and good antifreeze __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

12-06-2013, 09:27 AM	#3
Tom Vogel 2WD Jimmy Join Date: Mar 2005 Location: Davis County, Utah Posts: 2,565	Re: Heater Emergency!!! Have you put your hands on the heater hoses to see that they are warm and that the coolant is circulating in there? Is the heater valve opening and closing? And, of course, youve got the radiator topped off and full, right? That thing should toast you right out of there.

12-06-2013, 09:36 AM	#4
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: Heater Emergency!!! I'd check the heater valve. BEWARE there are 2 types that look similar. One that opens on vacuum and one that closes on vacuum. I think we want the close on vacuum type. As Tom said check the heater hoses. Make sure BOTH of them get hot. __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

12-06-2013, 09:46 AM	#5
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Re: Heater Emergency!!! How hot are we talking? Both get pretty warm after the truck runs a little

12-06-2013, 10:06 AM	#6
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Re: Heater Emergency!!! Hoses, that is

12-06-2013, 10:06 AM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: Heater Emergency!!! Check the cables on the dash unit. Make sure they operate the door for the hot air. Just because they slide back and forth doesn't mean anything. U have to watch and see them working. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

12-06-2013, 10:09 AM	#8
Lee H Registered User Join Date: Jun 2010 Location: Upland Ca Posts: 4,147	Re: Heater Emergency!!! My heater will not blow hot air after just idling. It takes being driven a few miles and then it heats up slowly. After 3-4 miles it's really hot. __________________ 1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703

12-06-2013, 10:44 AM	#9
Mr Chevorlet Rusty Nuts Join Date: Sep 2008 Location: Clever Missouri Posts: 1,338	Re: Heater Emergency!!! I would say also check to see if the flapper door inside the heater box is open to let the heat from the heater core to blow out. __________________ (Clever Missouri) Southwest Larry Mr Chevrolet My Build, The Marathon Truck http://67-72chevytrucks.com/vboard/s...d.php?t=604414

12-06-2013, 11:37 AM	#11
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Re: Heater Emergency!!! Thanks for all of the help guys, I really appreciate it. As it turns out, my radiator wasn't completely full. I topped it off before I went to class this morning and I'm going to burp my coolant system during shop today to get all of the air out (just in case). I'm not sure if my blend door is working right, but I think it is because when I move the lever, the air flow through my floor vent changes. I'll make sure it is when I replace my in-cab gaskets either tonight or this weekend. As for y'all who said to check my heater valves, I forgot to mention that the one of the POs by-passed them and installed straight hoses.

12-06-2013, 02:01 PM	#12
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Re: Heater Emergency!!! One more question. How do you guys have your heater hoses routed? I've got the one from my water pump going to the inlet of my core at the bottom and the top return line going to the radiator. Is this right or wrong? The PO had them routed this way so that's how I did them.

12-07-2013, 01:24 AM	#14
1972GMCsierra4x4 Registered User Join Date: Feb 2013 Location: Winchester Kansas Posts: 145	Re: Heater Emergency!!! Glad to say that my heater works awesome now! Thanks to all who gave advice!



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