heat blowing cold - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jamon8 · 03-25-2008, 01:56 PM

boy am I glad the temps are up here in S IL

all of a sudden my heat is blowing cold

any ideas

69rut · 03-25-2008, 02:37 PM

Here are some ideas:
Heater core blocked, this could be internal or external

Fan motor not working, fan broken

Thermostat stuck open

Heater control valve closed

Cab duct work not in proper position

**special-K** · 03-25-2008, 02:39 PM

Low on coolant?

**lks dcvn** · 03-25-2008, 03:50 PM

Just a guess, but there could be leaves, pine needles, rodents, etc. living in your heater box...

Mine works well enough in my beater, but I will be taking the cowl off - cleaning that stuff out (putting a fiberglass screen under the cowl opening) and putting it back on...

Then I will be removing the box under the hood and making sure that everything is clear (no junk in there) and then giving it another run...

I have been told that the heaters in these trucks sometimes work too well...

When I turn on my blower in the cab - I get an assortment of leaves, etc. that comes out of the ductwork (top of the dash and below) so I know that there is stuff in there...just hasn't been warm (and dry enough) to do it yet.

The other options are also valid.

Good luck.

jamon8 · 03-26-2008, 03:10 PM

thanks guys for the quick replies

all of a sudden the heat started to work yesterday

I am going to check the coolant level today and the cowl

03-25-2008, 01:56 PM	#1
jamon8 Registered User Join Date: Apr 2006 Location: southern Il Posts: 335	heat blowing cold boy am I glad the temps are up here in S IL all of a sudden my heat is blowing cold any ideas

03-25-2008, 02:37 PM	#2
69rut Registered User Join Date: Sep 2006 Location: SE Virginia Posts: 158	Re: heat blowing cold Here are some ideas: Heater core blocked, this could be internal or external Fan motor not working, fan broken Thermostat stuck open Heater control valve closed Cab duct work not in proper position __________________ trailers are for boats

03-25-2008, 02:39 PM	#3
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,858	Re: heat blowing cold Low on coolant? __________________ "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 ~

03-25-2008, 03:50 PM	#4
lks dcvn Registered User Join Date: Jan 2007 Location: Columbus, Ohio Posts: 4,339	Re: heat blowing cold Just a guess, but there could be leaves, pine needles, rodents, etc. living in your heater box... Mine works well enough in my beater, but I will be taking the cowl off - cleaning that stuff out (putting a fiberglass screen under the cowl opening) and putting it back on... Then I will be removing the box under the hood and making sure that everything is clear (no junk in there) and then giving it another run... I have been told that the heaters in these trucks sometimes work too well... When I turn on my blower in the cab - I get an assortment of leaves, etc. that comes out of the ductwork (top of the dash and below) so I know that there is stuff in there...just hasn't been warm (and dry enough) to do it yet. The other options are also valid. Good luck.

03-26-2008, 03:10 PM	#5
jamon8 Registered User Join Date: Apr 2006 Location: southern Il Posts: 335	Re: heat blowing cold thanks guys for the quick replies all of a sudden the heat started to work yesterday I am going to check the coolant level today and the cowl



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