Tom Cin

Trying for the third time ,I have a 98 that will not put out heat,blows cold air,top rad. hose is hot .In the manual it says that tells me it circulating .Any advise to be given.

99xj1

Are both the heater hoses hot as well?

Tom Cin

No just the top

Tom Cin

Haynes Repair Manual tells me the water is cerculating if the top is hot I don't understand that.

99xj1

I would guess both would be hot if it's circulating. You could pull both heater hoses off and hook a garden hose to one of them to ensure that heater core isn't plugged.

Tom Cin

Had the same thought, just wondering if it has a door not in place,the blower works fine and switches from heat @ floor and front,also defrost.

99xj1

It might have a broken blend door but i would check to see if the heater core isn't plugged first. I had an '87 xj that i put a new water pump in and then had no heat. I did the garden hose test and it worked fine when i hooked them back up. I think it must have had an air bubble in the core or something. Have you recently changed anti freeze, thermostat or water pump, etc?

99xj1

I see your new here also. Funny I'm trying to fix a heater related issue too.

Tom Cin

Yes' new,the thing only has 40k and have not changed anything yet bought it at an auction,I will try the the hose set up and see.

KSXJ

After I changed my heater core the heater was still not hot. When I shut off the engine you could hear coolant running into the heater core. It was a air bubble in the system. I just squeezed the top radiator hose with the radiator cap off and you could see the air bubbles come out. Repeated this several times while adding antifreeze. Now it is nice and toasty.

mcnslayer

Ok what you have is a cloged heater core, If only one heater hose is hot you have a blockage in your core, now there are a few ways you can flush it

The easiest way is to disconect the heater hoses from the thermostat housing put the uper house in aempty bucket and use a garden hose nosel to force water through the heater core.

If that dosn't work get some wheel cleaning acid (napa has it by the gallon) remove heater hoses from the thermostat housing, elevate houses and insert funel into upper hose(wear eye protection this part sucks),poor acid into upper heater hose let sit untill it works its way through heater core and starts to come out lower hose,(again I must say acid in the eye hurts wear eye protection )once fluid is into lower hose put upper hose end into a bucket and insert blow nosel into lower heater hose and blow air through heater core.

If that dosn't work time to change heater core good luck with that book time pays 5 hours it takes me at least 6-7 maybe I just suck but thats what it takes me

98jeepcher

Go to you tube and type in unclogging a heater core click on the one by eric the car guy this will help you.

Tom Cin

Hey'
Heater core was plugged, I removed both hoses and added a female garden hose end on each and flushed through both ends a few times . Water flow got better each time. Heat is now cooking.

Thanks to all !

TTMK5

bout 2 hrs from start to finish

1 disconnected heatercore hoses near tstat.
2 used air hose to clear coolant.
3 dumped in CLR with hoses raised till full
4 let sit for 20 mins
5 air through top hose to puch out clr
6 through same hose ran garden hose to flush (10mins)
7 connected hoses
8 inclined front of car to raise radiator
9 open radiator cap
10 start car with heat on high
11 add fluid to top of cap and to fill line in resevior
12 squeeze top hose to release air through radiator cap
(repeat steps 11 and 12 till no more bubbles, took me 15 mins)

replace cap and drive with heat

***see pic of my setup (white hose is from garden hose to top core hose, red is from lower core hose to bucket)

p.s. i used electrical tape to hold/seal pex pipes to extend hoses to drain and flush properly

please dispose of coolant properly

thanks to TJWALKER (serior member) for the CLR idea