heater/cooling problems, need some help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

texasfunk · 11-20-2009, 10:39 PM

ok, well, its abt 30 degrees here in the mornings now, and something weird has been happening, the heater works great and the temp gauge stays in the middle while moving, but when i stop at a light, and its at idle, the truck starts to get warm (never overheats) but the needle goes up quite a bit, and the heater stops working and it just blows cold air? even in the summer in 100 degree weather the truck never went past the middle, why is it now?

Fastest32 · 11-21-2009, 12:22 AM

Could be that your fan clutch is not working so the fan isn't pulling enough air and that's why it's getting hot while stopped. I don't know about it blowing cold air though. That's wierd

menace121978 · 11-21-2009, 01:38 AM

sounds like the heater core is clogged up or something along those lines.

TDS-MN · 11-23-2009, 10:09 AM

Have you checked your coolant level? Both symptoms could be indicating that you are down below full.

**old Rusty C10** · 11-23-2009, 04:55 PM

im betting coolant level and or thermostat

cableguy0 · 11-23-2009, 05:56 PM

definately sounds like low coolant level. a plugged heater core wouldnt work at all. what happens is when the water pump stops pumping hard like when your driving the air bubble rises up and and the sensor no longer is submerged in coolant to get a proper reading. they dont read air very well at all. top off the radiator and fill the coolant bottle to proper level run the truck let it burp and fill refill if needed

11-20-2009, 10:39 PM	#1
texasfunk Registered User Join Date: Jun 2009 Location: Lubbock, TX Posts: 1,671	heater/cooling problems, need some help! ok, well, its abt 30 degrees here in the mornings now, and something weird has been happening, the heater works great and the temp gauge stays in the middle while moving, but when i stop at a light, and its at idle, the truck starts to get warm (never overheats) but the needle goes up quite a bit, and the heater stops working and it just blows cold air? even in the summer in 100 degree weather the truck never went past the middle, why is it now? __________________ 2006 GMC Sierra CCSB, 6.0 swap 2000 Chevy C3500 Crew Cab shortbed dually 1999 Chevy c2500 Crew Cab shortbed 1982 El Camino 350/350 1979 K5 2wd blazer bagged/bodied 1986 Monte Carlo SS 1991 Chevy CK SWB-67 clip and tailgate, bagged 350/700r4 1955 Chevy Bel Air 2014 Chevy Silverado ccsb

11-21-2009, 12:22 AM	#2
Fastest32 Registered User Join Date: Nov 2009 Location: Austin Texas Posts: 370	Re: heater/cooling problems, need some help! Could be that your fan clutch is not working so the fan isn't pulling enough air and that's why it's getting hot while stopped. I don't know about it blowing cold air though. That's wierd

11-21-2009, 01:38 AM	#3
menace121978 Registered User Join Date: Jan 2009 Location: orangevale, ca Posts: 3,626	Re: heater/cooling problems, need some help! sounds like the heater core is clogged up or something along those lines. __________________ "Dennis the Menace" 1978 Silverado (2wd, 1/2 ton, short bed)complete nut & bolt frame off restomod LQ9/4L80E MY LS SWAP/FRAME OFF BUILD BOOK 2006 TBSS way too much to list

11-23-2009, 10:09 AM	#4
TDS-MN Registered User Join Date: Sep 2009 Location: Mpls, MN USA Posts: 151	Re: heater/cooling problems, need some help! Have you checked your coolant level? Both symptoms could be indicating that you are down below full. __________________ TomS. '98 S-10 Blazer 4dr 4wd - 4.3, AT, stock & '85 K-10 w/ 305, 700r4, np208, and RUST! SOLD Dec 2014

11-23-2009, 04:55 PM	#5
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,277	Re: heater/cooling problems, need some help! im betting coolant level and or thermostat __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-23-2009, 05:56 PM	#6
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: heater/cooling problems, need some help! definately sounds like low coolant level. a plugged heater core wouldnt work at all. what happens is when the water pump stops pumping hard like when your driving the air bubble rises up and and the sensor no longer is submerged in coolant to get a proper reading. they dont read air very well at all. top off the radiator and fill the coolant bottle to proper level run the truck let it burp and fill refill if needed __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.



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