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#1 |
Registered User
Join Date: Oct 2009
Location: Kansas City, MO
Posts: 6
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Heater/Defrost Issues
Ive been trying to get my heat workin. My windsheid isnt defrosting all the way and the other windows keep fogging. I replaced my blower motor in the fall because leaves were getting in the heater box and the motor failed. I had a leak in the core. Cleaned the leaves out and replaced it. I dont think the temperature comming out of the vents is high enough. Also I dont think there is enough air comming out of the vents compared to a newer vehicle. I think my hoses are right. Small hose from the bottom going to the water pump and big hose from the top going to the intake. QUESTION! Does the air going through the core come from the outside? Thats what it looks like. Was wondering if that has anything to do with it. My truck is a heat only cab, no ac.
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#2 |
Registered User
Join Date: Jun 2009
Location: Arlington Texas
Posts: 602
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Re: Heater/Defrost Issues
My heat only cab sucked, I installed a complete ac system and it blows so much harder. But I still have issues with windows and defrosting. If I crack the window just a little to let the fresh air in the windows defrost better.
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1970 GMC truck ![]() 1988 Harley 1200 Sportster ![]() |
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#3 |
Junior Member
![]() Join Date: Mar 2007
Location: DAYTON
Posts: 505
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Re: Heater/Defrost Issues
Is your motor getting hot enough? have the right thermostat in it? is the radiator full?
I have a 6 cly with a heat only cab & it gets plenty hot. takes a min but gets hot. not like a new truck but plenty enough...
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frontstreetcycle on Instagram |
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#4 |
Registered User
Join Date: Oct 2009
Location: Kansas City, MO
Posts: 6
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Re: Heater/Defrost Issues
Ill have to try a hotter tstat. I have a mechanical non/clutch fan. Its been cold and temp guage never passes a quarter of the way.
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#5 |
Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: Heater/Defrost Issues
The heater hoses are hooked up backwards as you described them. Large hose from top goes to the water pump and small hose from bottom goes to manifold. I am not sure if it will make a lot of difference.
Check the blower switch as it might not be functioning for the three speeds. The temp gauge may not be reading correctly. Outside air does go through the heater. If you get everything working, the heater and defroster will work for you. Here is a schematic of the heater hose routing. Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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#6 |
Junior Member
![]() Join Date: Mar 2007
Location: DAYTON
Posts: 505
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Re: Heater/Defrost Issues
the ol pizza box in front of the radiator helps when it gets real cold
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#7 |
Registered User
Join Date: Oct 2009
Location: Kansas City, MO
Posts: 6
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Re: Heater/Defrost Issues
ill have to try switching the hoses around and get a hotter tstat. the blower is getting about 13 volts on hi spd. i dont have an air flow prob because i previously changed the core and cleaned everything. its been cold in MO. i need to start cookin. thanks for the help
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#8 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Heater/Defrost Issues
the air diverter box is important part in defrosting// it is a very common failure fot the flapper valve to brake
you should have a 190degree thermostat
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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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#9 | |
Registered User
Join Date: Jul 2010
Location: Leesburg, VA
Posts: 420
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Re: Heater/Defrost Issues
Quote:
What problem does putting cardboard in front of the radiator help with? What are the symptoms that would indicate this would need to be done? When you do it, how much of the radiator should be blocked off, and for how long? Thanks for the help!
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Curt 1970 C/10, 250 L6 with Rochester BV carb, SM465 4 speed, 3.73 open rear Last edited by camrycurt; 02-09-2011 at 12:02 PM. |
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#10 |
Registered User
Join Date: Jan 2011
Location: Redmond, OR
Posts: 759
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Re: Heater/Defrost Issues
Cardboard or similar in front of the radiator will limit the airflow through the core at speed, retaining more heat. It is used by many trucks in areas where the temp gets below freezing to help keep the internals warmer.
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68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress |
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#11 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: Heater/Defrost Issues
Welcome to 40 year old technology.
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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 |
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#12 |
The Older Generation
![]() ![]() ![]() Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,493
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Re: Heater/Defrost Issues
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My bet is that you have a mouse nest and other junk blocking your heater core. You have to take the outside heater box off to clean it out. There is nothing wrong with this 40 year old technology when regular maintenance is performed on it. LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - Last edited by LockDoc; 02-02-2011 at 03:05 PM. |
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#13 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
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Re: Heater/Defrost Issues
Lockdoc is right.My 68 has better airflow and hotter air than my 2000 Dakota.I replaced the core,the fan and cleaned everything up.I also put in new hoses and air duct tubes.I did plumb it backwards to keep the hoses neater.Not only that but I replaced the radiator with a 4 row,really keeps the 6 cool.The left tank is so hot you can hardly touch it and the right is almost cool enough to drink.
BTW I also have waaaaaaaaayyyyyyyyyyy more cab to heat than most.
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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" Last edited by PanelDeland; 02-02-2011 at 06:22 PM. |
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#14 |
69' Chevy Stepside
![]() Join Date: Mar 2008
Location: Anchorage, Ak
Posts: 526
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Re: Heater/Defrost Issues
Are you getting full power to the blower motor when you select full speed, I know on some of my trucks the switch even though it goes all the way only selects the medium speed, instead of full speed on the fan motor.
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-Matthew -69' Chevy Custom/10 Shortbed Stepside 2WD "Copperhead" - Restored, 6.0L LQ9 Built. L92 Heads and LS3 Intake with Comp Cam 223/231 .610/.617 112 LSA, 4L60E with Shift Kit and Circle-D 3200 Stall Converter ~Build Thread -1957 Chevy BelAir 2 Door Post Sedan, Full Frame off Restoration done myself - 6.0L with T56 six speed -1957 Chevy BelAir 2 Door Post Sedan - Nearly rust free AK car, Project in the waiting -2003' Chevy Silverado SS AWD 6.0L! - Daily Driver |
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#15 |
Firefighter
Join Date: Feb 2001
Location: Yellville, Ar, USA
Posts: 1,943
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The heater in my 72 will run you out, you either have to turn it off or open a window. I went completely through my heater box, new hoses, new heater core, cleaned and painted inside and out and put a new 180 thermostat in the truck. I have no problems at all about it defrosting!!! lol
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'72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA ![]() ![]() |
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