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02-28-2012, 07:01 PM
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#1 |
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Registered User
Join Date: Sep 2008
Location: magalia,ca
Posts: 366
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A not so warm heater
hay guys my truck's heater is not very warm (blows luke warm) and the defrost works some what ok.
i figured on these old trucks it cant be to hard to get the heater working good again. i dont know if it matters but my truck has the factory harrison ac unit (non working right now). what should i look at or check to get the heater working good again? at 28 degrees last night and a frozen windshild (i thought) thank god im not driving my truck tonight.
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1970 2wd  3/4 ton- 2004 crate 350 thorley tri-y headers-edelbrock performer eps manifold 600cfm performer carb, crane cams energizer cam,lifters, dual 2.5 magnaflows, mallory HEI, powermaster 140 amp altenator, griffen aluminum radiator.(8 MPG )
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02-28-2012, 07:23 PM
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#2 |
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Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: A not so warm heater
one of the most common causes is the air phlenum by the blower motor and heater core is jam full of 40years of crap and does not allow any air to circulate properly over the heater core
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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 |
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02-28-2012, 08:15 PM
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#3 |
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20' Daredevil (Ret)
 
Join Date: May 2003
Location: Jefferson State
Posts: 13,594
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Re: A not so warm heater
A good thermostat (190 - 195) helps a lot. And the radiator should be full of coolant (big air pockets can't transfer heat very well).
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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02-28-2012, 08:21 PM
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#4 |
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Registered User
Join Date: Aug 2009
Location: Alden NY
Posts: 2,705
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Re: A not so warm heater
+1 on what cdowns said. Every one I have taken apart has had leaves, mouse nests, junk, etc. Since it is an AC equipped truck, make sure that the water valve on the inner fender is letting coolant through to the heater core. Make sure you have a 180 or 195 stat, and insure that you don't have any holes in the firewall (missing grommets etc.). If you end up taking it apart, replace the heater core. It is only $30 or so and it is not a job you want to do twice.
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1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 |
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02-28-2012, 10:34 PM
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#5 |
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Registered User
Join Date: Sep 2008
Location: magalia,ca
Posts: 366
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Re: A not so warm heater
is takeing the heater core out/cleaning a big project? or is it fairly simple?
how do i make sure the valve mounted on the fender well is allowing flow? are there any (HOW TO) theads dealing with the heater components? thanks for all ther replys.
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1970 2wd 3/4 ton- 2004 crate 350 thorley tri-y headers-edelbrock performer eps manifold 600cfm performer carb, crane cams energizer cam,lifters, dual 2.5 magnaflows, mallory HEI, powermaster 140 amp altenator, griffen aluminum radiator.(8 MPG)
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02-28-2012, 10:42 PM
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#6 |
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I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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Re: A not so warm heater
There are threads on it.Use the search bar at the top of the page or look thru the "FAQ's" truck related.
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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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02-28-2012, 11:54 PM
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#7 |
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Junior Member
Join Date: Dec 2006
Location: Southeast Missouri
Posts: 2,436
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Re: A not so warm heater
I think to get the heater core out the inner fender will have to be removed. If it has the valve in the line to the heater core you can tell if it is open if the hose is the same temperature on both sides of the valve.
None a/c trucks do not have a valve in the heater water hoses.
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'67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E. |
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02-29-2012, 09:01 AM
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#8 | |
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Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,253
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Re: A not so warm heater
Quote:
I retro'ed a stock AC system on to my truck where it previously had the non-AC heater. When I had the AC parts on the shop floor I cleaned them out real good so I know my system is free of debris. When I'm plowing my driveway it is WAY too hot in there. I always start plowing with the windows rolled up but usually have them rolled down by the time I'm done. 1. Verify that shut-off valve isn't stuck off. 2. Verify that you have a heater core box free of debris. If you pull the box out to clean it, make sure you get all the crud out of the vanes in/on the heater core itself. 3. Verify that you don't have air in your radiator/coolant system. Engine off, engine cold, take off radiator cap. Start the truck. Let it warm up. When the truck is warm and thermostat open (verify by looking into open radiator and seeing constant coolant flow) fill the radiator until no more air comes out. This process is referred to as "burping" your radiator. NOTE that if you didn't install a catch can on the overflow tube you'll get some overflow for a few days when you park the truck hot. I would do 1 and 3 first as they are way easier. If you still don't have heat do #2. After that you should have a situation where it is too hot in there with the heat on all the way.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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02-29-2012, 05:50 PM
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#9 |
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Registered User
Join Date: Apr 2010
Location: Russiaville
Posts: 203
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Re: A not so warm heater
You may also need to check and see if the passages inside the heater core are plugged. Rust scale from inside the engine block can accumulate in the passages. If both the upper and lower heater hose are the same temp, Its probably fine, but if one is cooler, its probably plugged.
I had this problem on my Stealth, I poured rust and iron remover thru it mixed with water. After letting it sit for about a half hour I flushed it with a garden hose. |
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03-03-2012, 12:29 PM
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#10 |
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Registered User
Join Date: Jan 2007
Location: Central Coast California
Posts: 1,026
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Re: A not so warm heater
Feed the core from the bottom and drain from the top...to keep air from accumulating in it.
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1972 K20 Suburban 5.7/700r4/NP205 Dana 44/H052 Sold  1972 C10 5.3L/4L60E 12bolt 5Lug - Sold 1971 K5 Blazer 6.0L LQ9 4L60E NP205 Dana 44/H052!!!  1970 K3500 1ton CrewCab 8.1L/Allison1000/NP205 Dana 60/14B!!!! - Sold 1984 K10 SWB 7.4L/4L80e/NP208 Corp 10/12 bolt Sold 1988 V30 CCLB 7.4L/TH400/NP205/Dana 60/Dana 70/3.73!!! (Sold) 2003 K2500HD 8.1/Allison1000/NP263
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