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#1 |
Registered User
Join Date: Sep 2005
Location: KANSAS
Posts: 23
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Heater won't blow hot
i've got a 68 C-10, 350, auto, (non-AC)....
the heater blows luke warm at best and the blower would come on and off (loose prongs on heater switch), so... i replaced the heater core, heater switch and all the gaskets (pulled off interior and exterior boxes). now all the speeds work great, it blows really hard too - but - still won't blow hot. i noticed that the heater blower speed resistor is falling apart (original cardboard type base). would that have anything to do with it. by it's title it doesn't seem like it - but i can't imagine what else the problem could be. (my old 72 would sweat me out of the cab in winters. this 68 won't even defrost the windows) any help is greatly appreciated!!! |
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#2 |
Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: Heater won't blow hot
my 68 dont defrost the windows either..but havent torn into it yet..whats the first thing to look for..mine blows a lil bit not very hard..and its barely luke warm also...what do i look for thanks
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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#3 |
Out of the carpool lane.
Join Date: Jan 2000
Location: Clark Co, WA
Posts: 5,673
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Re: Heater won't blow hot
Is your coolant level low? That would be the first thing to check. There was another thread similar just this week. I'll try to find it.
Here ya go: http://67-72chevytrucks.com/vboard/s...ghlight=heater
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1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten... Last edited by Brad; 11-22-2008 at 09:54 PM. |
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#4 | |
Registered User
Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: Heater won't blow hot
is there a valve in the heater hoses/lines? Is one of the fittings (water pump or manifold) plugged up with rust? With the motor running at temperature, are the heater hoses hot?
The resistor is in the airflow to cool it off while it is changing voltage to heat. Quote:
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Oscar '72 Shortbed Fleetside '95 Jimmy 4X4 '69 GMC Custom Camper |
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#5 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Heater won't blow hot
the resistor is what selects the blower speeds, so that isn't the issue.
Since you replaced the core, there's only a few options left, either your coolant level is low, or the hoses aren't routed properly (one to the intake, and the other to the water pump or to the rad) Or, the flapper in the heater box isn't making a good seal, either from bed seals, or not moving all the way to close the door from cold outside air. |
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#6 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,219
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Re: Heater won't blow hot
With the engine warm & running wrap your hand around a heater hose. You should not be able to hold on for more then 2-3 seconds. Both should be same. If one is hot & the other is not ther is poor circulation. I take it you have a good thermostat in it. If they both are hot its like Longhorn says the flaper is not closing.
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#7 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Heater won't blow hot
what temp is your thermostat?do you have the hoses routed correctly one from the water pump and one from the radiator?
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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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#8 |
PROJECT 7DEUCE
![]() Join Date: Dec 2002
Location: GRANTS PASS OR
Posts: 21,608
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Re: Heater won't blow hot
I just fixed this problem on my blazer the cable had somehow came off the little diverter box door and I would only get luke warm air. I slipped the cable end loop back on and now I have hot air..
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GO BIG GREEN ![]() MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
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