Jimmy won't heat up?

Tiny
BGURALUICK
  • MEMBER
  • 1991 GMC JIMMY
  • 250,000 MILES
My jimmy only blows warm air. I replaced heater core, thermostat, climate control, changed and flushed coolant. I have run out of options. PLEASE HELP AS WINTER IS HERE!
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Monday, November 14th, 2011 AT 4:50 AM

16 Replies

Tiny
FIXITMR
  • MEMBER
Is the blend door working properly?
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Monday, November 14th, 2011 AT 6:00 AM
Tiny
JJIMENEZ8891
  • MEMBER
Yea likly also on that old of a vehicle it is also actuated by vacume I belive make sure you check all vacume connections at firewall also
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Monday, November 14th, 2011 AT 7:31 AM
Tiny
FIXITMR
  • MEMBER
Check hoses at firewall in and out of core are both hot?
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Monday, November 14th, 2011 AT 8:02 AM
Tiny
WRENCHTECH
  • EXPERT
That one actually uses a cable to control temp. If both heater hoses are hot, then check the cable. If both hoses are not hot, then you could have a plugged core or engine temp problem.
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Monday, November 14th, 2011 AT 11:04 AM
Tiny
BGURALUICK
  • MEMBER
Is that located behind the glove box?
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Monday, November 14th, 2011 AT 2:37 PM
Tiny
WRENCHTECH
  • EXPERT
It's attached to the control head itself. Follow it to the blend door.
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Monday, November 14th, 2011 AT 10:25 PM
Tiny
BGURALUICK
  • MEMBER
I'm confused. Where is it?
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Monday, November 14th, 2011 AT 10:50 PM
Tiny
WRENCHTECH
  • EXPERT
It's attached to the back of the control that you are trying to control the heat with.
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Monday, November 14th, 2011 AT 11:00 PM
Tiny
BGURALUICK
  • MEMBER
So how do I check if it works properly?
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Tuesday, November 15th, 2011 AT 1:31 AM
Tiny
FIXITMR
  • MEMBER
Yah behind glove box. If you put it to cold does heat stop coming out? And what did you mean when you said you replaced "climate control"?
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Tuesday, November 15th, 2011 AT 6:25 AM
Tiny
BGURALUICK
  • MEMBER
I replaced the controls for the heat/air conditioning. The one that controls the temp and fan speed etc.
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Tuesday, November 15th, 2011 AT 1:46 PM
Tiny
FIXITMR
  • MEMBER
Do you have S10 or full size?
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Wednesday, November 16th, 2011 AT 5:26 AM
Tiny
BGURALUICK
  • MEMBER
I have a 4 door 4.3l sle
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Wednesday, November 16th, 2011 AT 5:32 AM
Tiny
FIXITMR
  • MEMBER
So have you checked blend door travel to see if it's hitting both stops? Opening and closing completely?
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Wednesday, November 16th, 2011 AT 3:50 PM
Tiny
BGURALUICK
  • MEMBER
I'm gonna try it when I get home from work
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Wednesday, November 16th, 2011 AT 11:13 PM
Tiny
PROAUTOTECH
  • EXPERT
There could be an obstruction in the exit of the water pump which "powers" the heater core. You said it is a new core. Try flushing the core anyway, in hopes to flush out the pump in the process. I've seen it in a suburban before, different vehicle I know, but same concept. Flush the waterpump by itself if you can.
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Tuesday, December 6th, 2011 AT 4:50 AM

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