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Old 09-12-2008, 06:11 PM   #1
rscam
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No heat. Help!!

I have completely rebulit my truck and have no Heat. First I had a 160 degree TS and I thought that was to low so I put a 195 in it. Still no heat. I mean not even a little. I have checked the cable through the grommet at the firewall and it is hooked up and functional. That door is AIR/FAN and moves about 20 degrees from one end to the other. The HEAT selector cable is also fucntional. and the DEF works correctly from floor to Defrost. I have the supply side of the (NEW)heater core comes from the water pump and the return goes to the top right corner of the radiator. The return is on top of the HC and the supply is on the bottom of the HC. I have a 4 core radiator. The only thimg I can think of is to put the supply on the intake before the thermostat so I will get heated coolant from the engine not the cooler side of the thermostat. Anyone have any other ideas?
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Old 09-12-2008, 06:17 PM   #2
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Re: No heat. Help!!

Yep your supply comes from intake and return to water pump or radiator. You are using the cooled water from the pump instead of heated from the intake.

Last edited by john; 09-12-2008 at 06:45 PM.
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Old 09-12-2008, 06:18 PM   #3
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Re: No heat. Help!!

if it was a new rad is there a plug in the heaters nipple on the rad?
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Old 09-12-2008, 06:19 PM   #4
68gmsee
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Re: No heat. Help!!

Could be the heater control valve.. May look good and opens and closes but could be broken on the inside...
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Old 09-12-2008, 08:02 PM   #5
passthebuck
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Re: No heat. Help!!

My heater core was plugged SOLID internally & after replacement, I've now got mega heat (& I'm a Canadian so I know about these things...)
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Old 09-12-2008, 09:51 PM   #6
rscam
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Re: No heat. Help!!

Thanks for the replies. I think I will move the HC supply line to the intake. When I bought this truck it didn't have an engine or radiator so I had to find pictures on the internet to put it back together by. I guess I found the wrong pictures to reference.
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Old 09-13-2008, 12:25 PM   #7
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Re: No heat. Help!!

Quote:
Originally Posted by rscam View Post
I have completely rebulit my truck and have no Heat. First I had a 160 degree TS and I thought that was to low so I put a 195 in it. Still no heat. I mean not even a little. I have checked the cable through the grommet at the firewall and it is hooked up and functional. That door is AIR/FAN and moves about 20 degrees from one end to the other. The HEAT selector cable is also fucntional. and the DEF works correctly from floor to Defrost. I have the supply side of the (NEW)heater core comes from the water pump and the return goes to the top right corner of the radiator. The return is on top of the HC and the supply is on the bottom of the HC. I have a 4 core radiator. The only thimg I can think of is to put the supply on the intake before the thermostat so I will get heated coolant from the engine not the cooler side of the thermostat. Anyone have any other ideas?
The supply has to come from the water pump to force water through the heater core and return to either the radiator or the intake manifold. If you have a stock setup with the control valve in the supply side you need to check the operation of this valve. It is controlled by vacuum from the heater controls.
Sorry this is backwards supply comes from manifold and returns to water pump
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Last edited by haysonj; 09-13-2008 at 12:38 PM. Reason: add picture
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Old 09-13-2008, 09:22 PM   #8
knsmodels
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Re: No heat. Help!!

did you check the fluid level of the radiator.....i know if i let my coolant level decline the heat will stop working.......just one more avenue to check......
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