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Discussion Starter #1
Hey guys!

I've got a '90 V2500 Suburban wich is the ultimate tow rig and is used as such daily...
But...
As with any older Chevy truck I've owned over the years I can't seem to find a way to get any kind of heat out of the heater system! This sucks when it's 15 degrees outside like it was last night.
The engine warms up the way it should, I replaced the heater core and the hoses going into the heater core get nice and hot, yet, when I turn the blower on all I get is icecold air *brrr*
It does have A/C wich doesn't work anyway so it can't be that...

Any help is appreciated!
Mary Ann.
 

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hi Mary Ann!! welcome to the site!!
maybe the thermostat is weak, and might need replaced? my 89 is the same, the heater is slow to warm up
 

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hi Mary Ann!! welcome to the site!!
maybe the thermostat is weak, and might need replaced? my 89 is the same, the heater is slow to warm up
The engine warms up fast actually and melts the snow off the hood quickly. If only the cabin would get that warm :lol:
When I put my hand on the heater box where the heater core is located that feels nice and warm also. This makes me think there is outside air blowing in somehow?
 

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After the engine has warmed up, are the heater core hoses hot?
 

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you might also want to check to make sure that the heater box is sealed up. if nto it sould be sucking the cold air out of the cab. Also check the a/c evaporator to see if it is clogged up with dirt.
 

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Obviously from what you're saying the heat is getting to the heater core just fine. It really sounds like some of the flaps may be stuck in such a way that the fan is sucking fresh air in only, and bypassing the heater core. Kinda sounds like one of the doors is stuck in the A/C position, and bypassing the heater core.
You may have to take the dash apart to make sure there is nothing preventing the diffuser doors from opening/closing.

Does your burb have a pushbutton interface for controlling the heat, and A/C?
If so, it likely uses a vac line to control those doors. You may have a break in a vac line.
If it uses sliders to control heat and A/C then it more than likely uses cables. In which case if something is binding you'll feel extra resistance in the slider control.

Sucks that this is happening while it's cold out. Hope you have a garage to work in.
 

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My vote is for a vac line leak. My 91 R1500 has a slider-style control, and uses vacuum for the vent door and the fresh/recirc door. Whenever I have a vac leak, my blend doors stop working. Good luck!
 

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Discussion Starter #8
Obviously from what you're saying the heat is getting to the heater core just fine. It really sounds like some of the flaps may be stuck in such a way that the fan is sucking fresh air in only, and bypassing the heater core. Kinda sounds like one of the doors is stuck in the A/C position, and bypassing the heater core.
You may have to take the dash apart to make sure there is nothing preventing the diffuser doors from opening/closing.

Does your burb have a pushbutton interface for controlling the heat, and A/C?
If so, it likely uses a vac line to control those doors. You may have a break in a vac line.
If it uses sliders to control heat and A/C then it more than likely uses cables. In which case if something is binding you'll feel extra resistance in the slider control.

Sucks that this is happening while it's cold out. Hope you have a garage to work in.
No garage to work in I'm afraid but that's ok. I found the passenger side vent door to be stuck wide open, closed that, even ductaped it shut and it helped a bit but it's still not quite there. I'm afraid I'll have to yank the whole heater box out one of these days and I might as well install a new heater core at the same time, even if that still feels nice and hot inside the box, it's just not blowing it thru... tried to manually operate the flap with the glove box removed and that didn't make any difference.
 

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it is possible that u have a cloged heater core or a/c evaporater.
 
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