Heat not working on '88 Grand Wagoneer

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pjwoody88
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Heat not working on '88 Grand Wagoneer

Post by pjwoody88 »

Haven't been able to diagnose the problem yet but the heat doesn't work in my 1988 Grand Wagoneer. The AC works great, it gets really cold in there, but when I switch to heat, nothing. Anyone have any idea on what could be the issue?
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Tatsadasayago
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Re: Heat not working on '88 Grand Wagoneer

Post by Tatsadasayago »

I would suggest you start by confirming you have hot coolant going into and out of the heater core housing. If both hoses are hot to the touch, your fan may be inoperative or the housing filled with leaves etc. It could be as simple as the temp control valve or cable.
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jpswapmohn
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Re: Heat not working on '88 Grand Wagoneer

Post by jpswapmohn »

Your heat and A/C systems are totally separate. I would start by checking the blower motor resistor. It is mounted in the heater coil housing under the hood. The A/C one is under the dash, mounted in the vent system, if i recall correctly. They are the same. Easy check is to take the one for the A/C (known good since your a/c works well) and put it in place of the heater resistor and see if it works.
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az chip
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Re: Heat not working on '88 Grand Wagoneer

Post by az chip »

Check the hoses are not rotted off under the dash to the vacuum controllers. Also check that there is vacuum at the dash switch. This along with what was said above.
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TeaBag
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Re: Heat not working on '88 Grand Wagoneer

Post by TeaBag »

Check that the Flap in the Heater Box is closed. If its open, it allows cold air to bypass the heater core. Its operated by a cable that attaches to the hot/cold temp adjustment on the climate control panel.

Sometimes the cable gets damaged, jammed or even breaks.

jfliege
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Re: Heat not working on '88 Grand Wagoneer

Post by jfliege »

az chip wrote:Check the hoses are not rotted off under the dash to the vacuum controllers. Also check that there is vacuum at the dash switch. This along with what was said above.
so the heat and air are connected to a vaccum tube. is that true in the 87s too. I did an engine swap to an 88 engine in my 87 that had an egr delete. I didn't know I needed to attach a vacuum hose to that I bet I need to run a new hose for my 4x4 too.
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jfliege
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Re: Heat not working on '88 Grand Wagoneer

Post by jfliege »

jfliege wrote:
az chip wrote:Check the hoses are not rotted off under the dash to the vacuum controllers. Also check that there is vacuum at the dash switch. This along with what was said above.
so the heat and air are connected to a vaccum tube. is that true in the 87s too. I did an engine swap to an 88 engine in my 87 that had an egr delete. I didn't know I needed to attach a vacuum hose to that I bet I need to run a new hose for my 4x4 too.
Ignore me I don't want to hijack this thread.
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candymancan
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Re: Heat not working on '88 Grand Wagoneer

Post by candymancan »

Mmm if i remember i dont think the later models have vacuum hoses on the a.c controls.. its just controled by cables isnt it ?
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