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

webfoot · 12-12-2011, 03:37 PM

It has been getting pretty cold around here lately, the last couple days the high temp has gotten clear into the low 20s. My heater seemed like it worked fine in the fall but as I was driving on the freeway in some thick fog it was freezing to the windshield and the defrost vents felt like they were blowing out 60 degree air. I was still pretty chilly despite having an arctic carhartt jacket on.

I would not think the cold air would keep the coolant THAT cold, does this sound more like a nearly plugged up heater core?

**70cst** · 12-12-2011, 04:07 PM

I would think there is an issue as you should be getting heat...

Ideas fellow board members?

domeier · 12-12-2011, 04:32 PM

Might want to take a look at the firewall, too. Plugging up all the air leaks makes a big difference.

trev1 · 12-12-2011, 04:34 PM

Sounds like the thermostat is stuck open. Engine is not getting up temp. Replace the thermostat and see if it helps.

Bert W · 12-12-2011, 04:49 PM

I was thinking a stuck thermostat also, or nor thermostat, or a low temp. thermostat. I like the plugging the holes idea also.

webfoot · 12-12-2011, 04:51 PM

Hadn't thought about the t-stat, that makes sense though.

PanelDeland · 12-12-2011, 04:58 PM

Could also be a clogged heater core.Take the hoses loose and run the water hose thru it.Flush both ways.Especially if it's a newer replacement.For some reason they have made the lines thru them smaller and they clog easier.

trev1 · 12-12-2011, 05:00 PM

Yep...less than 20 bucks and less than 20 min.. first place I would start....IMO

cdowns · 12-12-2011, 05:35 PM

i'd take the blower motor out and check to seee if the phlenum is clogged with 40 years of crap causing no air circulation

cost is $20 less than that $20// i've found time with no money is better than money alot of times when solving problems

slikside · 12-12-2011, 06:50 PM

Quote:

Originally Posted by cdowns

i'd take the blower motor out and check to seee if the phlenum is clogged with 40 years of crap causing no air circulation

cost is $20 less than that $20// i've found time with no money is better than money alot of times when solving problems

This certainly won't hurt, but it won't help it get hotter. How is the airflow? If you can feel some volume coming through, it's not the blower. I'm inclined to think more of a core blockage or the thermostat.

oldblue1968chevy · 12-12-2011, 05:47 PM

im with cdowns

**VetteVet** · 12-12-2011, 06:54 PM

If it sucks then the motor is running backwards.

sorry J/K

First thing is check the air flow from the vents. Then check the lever on the heat door control for free travel no binding. Then check the top and bottom heater hoses after the engine warms up for equal temperature both warm to hot. If you have AC then the control valve might be stuck on the inlet hose to the heater core.

webfoot · 12-12-2011, 06:57 PM

Air volume is decent, I'd say similar to what my chevelle puts out. Still what I would consider inadequate, but I think thats about as good as these ol things get.

Dark Knight · 12-12-2011, 10:40 PM

If your engine isn't getting up to operating temp, try blocking half of the radiator with a piece of cardboard. Watch your temp gauge though. I've got a 160 t-stat in mine, but didn't change it before winter. Now my truck barely warms up. The cardboard works. (Then I noticed all the big-rigs with the snap on covers over the front of their trucks.)

1972RedNeck · 12-12-2011, 11:06 PM

Quote:

Originally Posted by webfoot

Still what I would consider inadequate, but I think thats about as good as these ol things get.

These trucks have HUGE heater cores. I've got a little laser-pointer-thermometer-thingy-mabobber and it says my output air temp is 145* on a 30* day. I have a 180* thermostat.

z10kl · 12-12-2011, 11:12 PM

Is the air comeing out warm at a low fan speed and then cools when you turn the fan to high? If so the core is clogged and the air is cooling it faster than the water can move though it. Mine was doing this and I removed the hoses form the motor and took a hose and blew through it backwards. At first hardly any water would go through. Then some grit and rust started coming out and I could tell The flow was getting better. Heats better now.

**special-K** · 12-13-2011, 09:06 AM

It must be in the thermostat. You're not "making" heat. These trucks have heaters that are second to none. They put out more heat than you will ever need. If the heater core was clogged you'd feel a hot heater hose going in and a cooler one going out. If the plenum was clogged you'd still have the heat,just less air bowing through. In fact,you'd have a very hot heater. I never wear a jacket while in my truck and it's rare the fan is ever blowing more than low. It only goes on high to deice when I first start it up or to defog when I get in the truck wet. Then,the temp is either set down or if it's on hot to dry the air I need to open the wing vent or crack a window. A proper working heater will make you sweat like a pig with fan on high and temperature set on hot.

franks72 · 12-13-2011, 11:07 AM

This is what I found in mine.
http://67-72chevytrucks.com/vboard/s...d.php?t=396843

trev1 · 12-14-2011, 07:35 AM

Webfoot,what did you find? Would sure like to know.

webfoot · 12-14-2011, 02:15 PM

Haven't played with it yet. We haven't been above freezing for about 2 weeks now so my motivation to go out and work on it is low. I will update the thread when I find out.

Mudder · 12-14-2011, 08:02 PM

Low water/anti freeze mixture. Make sure it has plenty of water in it. After I redid my heater with new door rubber it would actually run you out.

12-12-2011, 03:37 PM	#1
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Heater sucks!!! It has been getting pretty cold around here lately, the last couple days the high temp has gotten clear into the low 20s. My heater seemed like it worked fine in the fall but as I was driving on the freeway in some thick fog it was freezing to the windshield and the defrost vents felt like they were blowing out 60 degree air. I was still pretty chilly despite having an arctic carhartt jacket on. I would not think the cold air would keep the coolant THAT cold, does this sound more like a nearly plugged up heater core? __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC.

12-12-2011, 04:07 PM	#2
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,373	Re: Heater sucks!!! I would think there is an issue as you should be getting heat... Ideas fellow board members? __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

12-12-2011, 04:32 PM	#3
domeier Registered User Join Date: Sep 2011 Location: San Jose, California Posts: 784	Re: Heater sucks!!! Might want to take a look at the firewall, too. Plugging up all the air leaks makes a big difference.

12-12-2011, 04:34 PM	#4
trev1 Registered User Join Date: Nov 2010 Location: Goodman,Mo Posts: 155	Re: Heater sucks!!! Sounds like the thermostat is stuck open. Engine is not getting up temp. Replace the thermostat and see if it helps.

12-12-2011, 04:49 PM	#5
Bert W Registered User Join Date: Dec 2008 Location: Jackson, MS Posts: 373	Re: Heater sucks!!! I was thinking a stuck thermostat also, or nor thermostat, or a low temp. thermostat. I like the plugging the holes idea also. __________________ 1968 Chevy C/10 LWB V8 1983 K5 Blazer 1989 C1500 Stepside Reg. Cab V8

12-12-2011, 04:51 PM	#6
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Re: Heater sucks!!! Hadn't thought about the t-stat, that makes sense though. __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC.

12-12-2011, 04:58 PM	#7
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Heater sucks!!! Could also be a clogged heater core.Take the hoses loose and run the water hose thru it.Flush both ways.Especially if it's a newer replacement.For some reason they have made the lines thru them smaller and they clog easier. __________________ 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"

12-12-2011, 05:00 PM	#8
trev1 Registered User Join Date: Nov 2010 Location: Goodman,Mo Posts: 155	Re: Heater sucks!!! Yep...less than 20 bucks and less than 20 min.. first place I would start....IMO

12-12-2011, 05:35 PM	#9
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Heater sucks!!! i'd take the blower motor out and check to seee if the phlenum is clogged with 40 years of crap causing no air circulation cost is $20 less than that $20// i've found time with no money is better than money alot of times when solving problems __________________ 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

12-12-2011, 05:47 PM	#11
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Heater sucks!!! im with cdowns __________________ 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

12-12-2011, 06:54 PM	#12
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,718	Re: Heater sucks!!! If it sucks then the motor is running backwards. sorry J/K First thing is check the air flow from the vents. Then check the lever on the heat door control for free travel no binding. Then check the top and bottom heater hoses after the engine warms up for equal temperature both warm to hot. If you have AC then the control valve might be stuck on the inlet hose to the heater core. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

12-12-2011, 06:57 PM	#13
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Re: Heater sucks!!! Air volume is decent, I'd say similar to what my chevelle puts out. Still what I would consider inadequate, but I think thats about as good as these ol things get. __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC.

12-12-2011, 10:40 PM	#14
Dark Knight Registered User Join Date: Dec 2008 Location: Pleak, Texas Posts: 420	Re: Heater sucks!!! If your engine isn't getting up to operating temp, try blocking half of the radiator with a piece of cardboard. Watch your temp gauge though. I've got a 160 t-stat in mine, but didn't change it before winter. Now my truck barely warms up. The cardboard works. (Then I noticed all the big-rigs with the snap on covers over the front of their trucks.) __________________ -1967 Chevrolet Fleetside LWB- 350 V8 w/thumpr cam, NV3500, 3.08 gears, A/C, PS -1983 Chevy Silverado C1500- 383 stroker, TH400 -1989 Chevy Silverado K1500 SWB- 5.3L swap, 700R4, 3.42 gears -And a '66 Ford Mustang- 200 I6, C4 trans, rust bucket "The only thing we have to fear is fear itself." -FDR (and maybe rust too) You've gotta be able to stop and steer before you can go fast!

12-12-2011, 11:12 PM	#16
z10kl Registered User Join Date: Oct 2006 Location: denver nc Posts: 97	Re: Heater sucks!!! Is the air comeing out warm at a low fan speed and then cools when you turn the fan to high? If so the core is clogged and the air is cooling it faster than the water can move though it. Mine was doing this and I removed the hoses form the motor and took a hose and blew through it backwards. At first hardly any water would go through. Then some grit and rust started coming out and I could tell The flow was getting better. Heats better now. __________________ 70 CST Bunch of old Camaros

12-13-2011, 09:06 AM	#17
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: Heater sucks!!! It must be in the thermostat. You're not "making" heat. These trucks have heaters that are second to none. They put out more heat than you will ever need. If the heater core was clogged you'd feel a hot heater hose going in and a cooler one going out. If the plenum was clogged you'd still have the heat,just less air bowing through. In fact,you'd have a very hot heater. I never wear a jacket while in my truck and it's rare the fan is ever blowing more than low. It only goes on high to deice when I first start it up or to defog when I get in the truck wet. Then,the temp is either set down or if it's on hot to dry the air I need to open the wing vent or crack a window. A proper working heater will make you sweat like a pig with fan on high and temperature set on hot. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~



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12-13-2011, 11:07 AM	#18
franks72 Junior Member Join Date: Mar 2005 Location: Wilmington DE Posts: 218	Re: Heater sucks!!! This is what I found in mine. http://67-72chevytrucks.com/vboard/s...d.php?t=396843 __________________ 72 cheyenne super BB402 TH400 Air Tack Tilt Posi P/S P/B AM/FM 12.96 @ 101.82 mph 60ft 1.82 12.39 @111.33 With a 180 shot nos 69 Camaro RS http://s94.photobucket.com/albums/l117/fdelcoglin/ email fdelcoglin@hotmail.com

12-14-2011, 07:35 AM	#19
trev1 Registered User Join Date: Nov 2010 Location: Goodman,Mo Posts: 155	Re: Heater sucks!!! Webfoot,what did you find? Would sure like to know.

12-14-2011, 02:15 PM	#20
webfoot Registered User Join Date: Nov 2007 Location: Hermiston, OR Posts: 947	Re: Heater sucks!!! Haven't played with it yet. We haven't been above freezing for about 2 weeks now so my motivation to go out and work on it is low. I will update the thread when I find out. __________________ *Running in place gets you nowhere fast.* -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC.

12-14-2011, 08:02 PM	#21
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Re: Heater sucks!!! Low water/anti freeze mixture. Make sure it has plenty of water in it. After I redid my heater with new door rubber it would actually run you out.

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