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heater doesn't work


Steelblade's Avatar
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10-05-03, 03:28 PM   #1  
Steelblade
heater doesn't work

I have a 1995 chevy caprice police model (V-8 engine, suspension, oil cooler, etc) but the heater doesn't seem to work. I backflushed the system, also blocked a section to make sure that I flushed through the heater coil in case there was a blockage of some kind, also accessed the heater core from the inside while the heater was running (Or turned on, anyway) and it never really got that hot. not too hot to touch with my bare hand, certainly. I also checked the hot/cold adjustment. Thought maybe the air wasn't switching over, but I was able to feel a change in air pressure as I switched from hot to cold and back again. Also felt it with the heater core cover off from under the dash, no air blockages that I could see or feel.

I'm thinking that the core should have been hot to the touch at least. The coolant is flowing through it, no blockages as I said, the engine doesnt have an overheating problem, though I wonder if it's not the water pump losing 'strength' over time anyway.

Does anyone have any suggestions?

Thanks,

Bruce

 
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10-05-03, 03:41 PM   #2  
Joe_F
Simple question:

Have you changed the thermostat? First place to start with a no heat complaint.

 
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10-05-03, 03:45 PM   #3  
Steelblade
Thermostat check. NOt more than 3 months old. New radiator cap, too.

 
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10-05-03, 03:48 PM   #4  
Joe_F
If you feel both heater hoses and they are not hot, that's an engine cooling system issue. If both hoses are hot, then it's a blend door issue inside the car.

 
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10-05-03, 07:50 PM   #5  
Steelblade
The heater hoses are both hot on the engine side of the firewall. Couldn't get to them on the passenger side of the firewall. I DID get to the heater core and that never got particularly hot, as I said. Not sure which of the two issues that points to, or if I need to dismantle the car a bit more.

Never heard of a blender door. Can you post a link describing one and maybe a hint on where to look for it?

Thanks

Bruce

 
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10-06-03, 05:21 AM   #6  
Sounds like a bad heater control valve, located in the 3/4" heater hose between the firewall and water pump.

 
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10-06-03, 06:54 AM   #7  
Joe_F
I just took a fast look at the GM parts catalog. There's a specific valve for the "SEO" police car, so make sure you hit a GM dealer to be sure you get the right thing.

According to GM it includes the hoses. Check the hose feel at the heater core area outside the car. If they are not hot there, the problem is with flow TO the core.

If they are hot there, the problem is inside with the blend door.

 
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10-06-03, 06:58 AM   #8  
on at least two occasions that i can think of, i have taken the hot water valve off to find a piece of rtv sealanat lodged in the valve.
the hoses should be too hot to hang on to on both sides(inlet and outlet). also, rapidly move the hot/cold knob from side to side and u should be able to hear the flapper inside the heater box close on both sides. at least u want to hear it when u slide it to the hot side, since it is a lack of heat issue.

 
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