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post #1 of (permalink) Old 02-08-2002, 01:44 AM
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Heater blows.....but not heat??

89 Chevy 1/2 ton. My heater blows...(pun intended) it will blow, change from defrost to panel, but it blows lukewarm at most???? Heater core was replaced about 2 years ago. Running a 185 thermostat? Radiator full. WHat can it be? It didnt work too well last year either come to think of it. I put in a CD player about 3 years ago, could I have knocked something lose?????

It is warm in TX, but gets kinda cold at night these days.
Thanks
SC

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post #2 of (permalink) Old 02-08-2002, 01:47 AM
 
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Re: Heater blows.....but not heat??

Heres a thought, did you use a test light or multimeter when you installed the cd player? Cause, theres these neat little vacuum lines running off the back of the blend door controls, the knob that selects heat/cool. They are colored, red, black, yellow, orange, etc. And they are same size as a 14-16 awg wire. I have seen alot of people probe these thinking there wires, and they punch a little hole and lose vacuum so that motor doesn't work anymore. So you may have done this and the vacuum motor that operates the blend door has stopped working.

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post #3 of (permalink) Old 02-08-2002, 02:05 AM
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Re: Heater blows.....but not heat??

No I didnt use a probe, havent ever used one. Could I have pulled one of the Vac. lines by accident?

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post #4 of (permalink) Old 02-08-2002, 02:09 AM
 
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Re: Heater blows.....but not heat??

Could have, most just push onto a nipple on the back of the knob. You can check and see if there hooked up. Also, you can get a hand vacuum pump and hook it to the line going to the blend door and see if the heat works better after pumping the handle a bit. That could mean that maybe you have a hole in the line or it's rotting or something. Did it ever work right after getting the new heater core?

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post #5 of (permalink) Old 02-08-2002, 02:41 AM
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Re: Heater blows.....but not heat??

Cant remember if it worked after I put in the core. it was summer time. My ac control dont have knobs, just buttons (with the little display screen). Are there vac. lines on this type of control?? I will check the lines in the AM.

post #6 of (permalink) Old 02-08-2002, 02:57 AM
 
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Re: Heater blows.....but not heat??

Oh, I was thinking 89 blazer. Umm, honestly I've never pulled the controls on a 88-94 style and I don't know for sure if there vacuum or mechanical or electronic. Anyway, if there not vacuum, a linkage may not have been set properly after putting everything back together. Maybe the door doesn't open completely or something. Only letting a litte bit of the air go through the heater part.

EDIT: Ok, just checked my wiring schematics and the 88-94's have servos. So, only electrical links between head and motors. Now, it's more than likely a problem of the motor has gone out, the heater core is bad, or a blockage in the lines somewhere.

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post #7 of (permalink) Old 02-08-2002, 03:46 AM
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Re: Heater blows.....but not heat??

Must be blocked then because it blows HARD, it just isnt warm. Unless you are talking about the blend motor.
Thanks for your replies

post #8 of (permalink) Old 02-08-2002, 02:17 PM
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Re: Heater blows.....but not heat??

Do you have a temp guage. If your thermostat is stuck open then your engine will never really get warm enough for the heater to work. If it is stuck closed then you over heat. Changing the thermostat is easy. You might want to just do that to make sure.

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post #9 of (permalink) Old 02-08-2002, 09:24 PM
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Re: Heater blows.....but not heat??

I changed my thermostat about 2 months ago. THe heat didnt work with the old one, and it dont work with the new one? My gauge works, runs about 160 usually.

post #10 of (permalink) Old 02-08-2002, 09:44 PM
 
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Re: Heater blows.....but not heat??

I'm still thinking you may have a blockage somewhere in the line. But, still check to make sure the blend door is operating correctly.

Jason
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