Heater blows air, sometimes warm, but not hot..

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Posts: 31

Date: Nov 24, 2008

Heater blows air, sometimes warm, but not hot..	Permalink

The heater in my 1999 Cherokee Sport does not blow what I would even come close to considering hot air, sometimes it is warm, other times it is cool. I have flushed the cooling system, it has what I believe to be a 190-195 degree thermostat in it. The heater hoses under the hood get hot to the touch, but it just doesn't transfer over to the heater. The heaters in both the 1989's I own/owned also leave something to be desired in this category as well. I thought the 160 thermostat may have had something to do with it, but even after changing it out, it still was not hot. Any ideas? Thanks in advance. __________________ 1999 Jeep Cherokee Sport 4X4 4.0L Auto 1989 Jeep Cherokee 4X4 4.0L 5-spd (Using more oil than gas...)

dstaub

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Posts: 523

Date: Nov 24, 2008

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LeadNotFollow (Adam) had pretty much the same situation on his rig a couple years ago i believe. and i think it was his heater core. find the two lines that are attached to the heater core and see if they are hot or not. that will tell you the most likely answer fairly quick. good luck.

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SCORE!: 1996 Cherokee Sport, bone stock, excellent condition, one owner, with currently 47,000 ORIGINAL miles!!

CURRENTLY: 2001 Cherokee Limited 4-dr, 33" Uniroyal Liberator A/Ts, 6-8" well built custom lift (sorry, i haven't measured yet).

SOLD: Project Rig: 87 Cherokee Pioneer 4dr. bone stock now. coming soon: 3" budget lift, go completely doorless and chop the rear cargo area out.

SOLD: '98 Cherokee Sport 2dr, 3" SkyJacker w/ 2" budget boost, 31" Truxxus meats, Protofab off-road bumpers & rock rails, KC Highlights

LEAD_NOT_FOLLOW

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Date: Nov 24, 2008

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I still don't have heat in my 1989 XJ....

It's come down to I know my heater core is clogged. I've tired the heater core flush several times, changed out the valve that controls it, bypassed the valve, and every other "fix" and it's not done anything to help. So I need to swap out my heater core. Problem is that it requires you to remove the entire dash and the FSM says it's a 11 hour job (thats with the right tools and the know how). I just havn't decided to tackle the huge job yet to swap it out.

With all that being said....

If your is a 1999, than you don't have a heater control valve under the engine bay. So that won't be the problem. If your fan blows, than we know it's not the blower motor resistor. Only other thing I can think of is their is a "door" under the dash that opens and closes the air going by the heater coor I belive. Make sure that is opening/closing correctly. I guess the point of it is to allow you to have the vent function, but not have it "hot" all the time.

If none of that works, I'd try to continue to flush your heater core. Simply take the upper and lower hose off of it under the engine bay, and run a garden hose to one side, turn it on and see all the brown gunk come out. I'd than hook it to the other side and flush it "backwards". Do that several times and see if it helps. I know your local auto supply store should sell an addative that you can buy to help flush it (it's a chemical) and will help get the "gunk" out. I tired it and it seemed to help. I wouldn't do it just to do it, I'd only use it as a last resort as it may cause the alum. in the heater core to oxidize faster and clog it faster in the future.

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'93 XJ Cherokee Sport - build thread
'89 XJ Cherokee Laredo - build thread
'88 MJ Comanche Pioneer SWB - build thread
'87 MJ Comanche LWB
'94 YJ Wrangler - build thread

Topic: Heater blows air, sometimes warm, but not hot..