'97+: Does the heater just plain suck in these things?

Up here in Western Pennsylvania, we love our heaters... well, maybe a bit too much . The heater in my '98 XJ just doesn't seem to be as powerful as I think it should be. It makes a lot of noise on high, and it gets plenty hot, but there isn't a lot of airflow on that setting.

I dunno, maybe I'm just being greedy. Does your '97+ seem to lack heater capacity?

I wouldn't be asking this if I wasn't sure that everything was functioning properly. I had the entire dashboard out during my XJ's reconstruction, which gave me the opportunity to remove and flush out the heater core, check all of the vacuum connections, and test the blower motor. The vent flaps open and close like they're supposed to, as well. Nothing seems to be at fault mechanically. I also removed and cleaned the vent ducting (this poor Jeep was owned by a slob before I picked it up; the whole thing needed disinfected).

I'm warmer in my YJ with no doors and no top in the dead of winter. Now that's a heater!

Do you have the setting on "vent" so it blows on your upper body not on "heat" so its blowing onto the floor? Dumb question I know.

Heater in my '93 will run you out, on Heat setting, not Vent.

Thats not normal. The 98 the better half has WILL BAKE you. I was going to suggest that perhaps the heater core was plugged up either from lack of proper flushing the cooling system and or plugged airflow through the fins. Both would be good places to check. The blower motor can also get crudded up and reduce air efficiency. If you had the dash apart as far as you said you did, you should have been able to see any issues with either airflow from the motor or stopped up cooling fins on the core. The only other thing to do is to flush the core when doing a coolant replacement, which you should be doing anyway...if you have ANY water flow when you do the flush, your core should be producing at least some heat. I like to flush the core by itself by disconnecting both heater hoses off of the water pump and thermostat and flushing through them with a garden hose. You should have a full stream of water both in and out of the core.

There is also the cable that works the heater door that you need to check too. The door is just above the left leg of the where the passenger sits. I've never actually seen it in daylight (for whatever reason, I always put it back on at night when we are going somewhere), but I've put it on about 10 times. I do it by feel. Reach up there and you will feel the door mechanism and there will be a little piece of cable sticking out with a ring on the end of it. The cable end is supposed to fit over the protrusion on the door. It takes 5 seconds for me to feel under the dash and put it back where its supposed to be. One day I'll fix it properly.

Some previous owner perhaps installed a lower temperature thermostat in the thermostat housing to try to overcome engine overheating issues. You need the 195 degree thermostat in it. Its easy enough to check as its only a couple of bolts that hold the housing on. Pull them off and have a look at the thermostat. I'd get a factory one as they have a nice air bleed valve in it. Put it in at the 12 o-clock position and you are good. WHen is the last time you flushed and filled the cooling system? This could be a good excuse for you to do a cooling system PM before winter finally sets in like its supposed to (Wx man says we have a couple of more days of mild wx here then the mercury is supposed to drop)

Dave

n5xl said:

Thats not normal. The 98 the better half has WILL BAKE you.
Dave

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i agree. mine will cook you if you're not careful

iroc86 said:

I'm warmer in my YJ with no doors and no top in the dead of winter. Now that's a heater!

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I agree. The YJs will melt your feet if you're not careful.

My 98 XJ pumps out more than enough heat. Sounds like you've got a plug in your core. What temp is your guage reading at normal cruising speed after more than 10 minutes of driving?

Well, at least it seems like there's a problem -- I would have been really disappointed if I came across a Jeep that didn't burn you up on its highest heater setting!

Yep, the heater is on the floor setting. I get a decent amount of airflow whenever it's on the vent/top setting, but still not that much. Front defroster seems to work well.

I replaced the cooling system components whenever I reconstructed this Jeep. New water pump, new hoses, new thermostat, flushed heater core, fresh coolant, etc. I guess it's possible that some junk is still stuck in the heater core that didn't come out, but I can't be completely sure. The Jeep warms up to 210 like any normal OBD-II car does (faster than the YJ, which is nice!). The air coming from the ducts is very hot.

As luck would have it, I have the glove box removed (trying to track down a dashboard noise), giving a clear view of the HVAC system under the dash. n5xl, are you referring to the door that opens when the climate control is set to "off" and closes when it's set to a heater mode? If so, that door is working properly. I can also see the blower motor fan when the door is open; there isn't any debris stuck on the cage.

I'll check under the dash again and see if anything else is goofed up. Might be a good idea to grab some fan voltage readings, too. Thanks for the help so far.

iroc86 said:

Well, at least it seems like there's a problem -- I would have been really disappointed if I came across a Jeep that didn't burn you up on its highest heater setting!

Yep, the heater is on the floor setting. I get a decent amount of airflow whenever it's on the vent/top setting, but still not that much. Front defroster seems to work well.

I replaced the cooling system components whenever I reconstructed this Jeep. New water pump, new hoses, new thermostat, flushed heater core, fresh coolant, etc. I guess it's possible that some junk is still stuck in the heater core that didn't come out, but I can't be completely sure. The Jeep warms up to 210 like any normal OBD-II car does (faster than the YJ, which is nice!). The air coming from the ducts is very hot.

As luck would have it, I have the glove box removed (trying to track down a dashboard noise), giving a clear view of the HVAC system under the dash. n5xl, are you referring to the door that opens when the climate control is set to "off" and closes when it's set to a heater mode? If so, that door is working properly. I can also see the blower motor fan when the door is open; there isn't any debris stuck on the cage.

I'll check under the dash again and see if anything else is goofed up. Might be a good idea to grab some fan voltage readings, too. Thanks for the help so far.

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How about the Air intake for the blower?

Just because you flushed the heater core doesn't mean it got all of the corrosion out. New heater cores are usually not that expensive, it's just the hassle of changing it. Used to work in a auto parts store and sold alot of cores after guys tried to flush them out.

Dumb question, I know, but have you considered a dead/dying blower fan? Mine died last winter and, OMG, the replacement will roast you alive--significantly more air flow.

My wife's 98 was very cold in the cabin and started to overheat. Flush and fill did nothing. New hoses did nothing. Turned out to be the water pump. It has toothless. The blades were gone. I replaced the pump and the heater will make cookies now.

I've never been impressed by the HVAC in my 97.

My 1990's gets almost hot enough to melt the ductwork I think. My bro's 2001 XJs heater works almost as good as mine also.

something is not right , my 97 will melt you down

I had a 98 and it is much better than my current 95. People always remarked how fast the 98 would throw a lot heat in winter (Canadian winter btw,so -20C) and how well the A/C cooled in summer (30C/90F).

I figured it was because the 4.0 makes a lot of heat and they did a good job at harnessing it for the HVAC...

My 90 was mediocre, at best until I replaced the heater core. Then it always got roasty inside. My "new" 99 heat feels so hot @ 215 engine temp that I might be able to make grilled cheese sandwiches on the dash. Something is definitely awry with yours. If the coolant wasn't flushed regularly, you may have lost the lube-goodness of the coolant and are now running a worn pump. Or it might be the core. Both items are relatively cheap insurance against all kinds of troubles. If it were me, I'd swap them both. If it ain't broke, take it apart and figure out why!!!

-Rich

Ugh, I've been sooo busy; there hasn't been any time to fix this silly heater. We're supposed to get snow tomorrow (high of 32º!) so I had better get started...

Anyway, I was thinking about the issue and I'm convinced that the heater core isn't the problem. I've always gotten really hot air; it's the airflow that's disappointing. Having a clogged heater core isn't going to restrict airflow. And, as I mentioned a few posts up, the water pump has already been replaced (though unrelated to the airflow theory).

Based upon everyone's responses, it seems that the problem lies either in the blower motor, the ducting, or the vacuum motors. I fussed around with the climate control on my way home from school today and it seems like the air just isn't getting routed properly -- a lot of "blowby" noise coming from behind the center of the dashboard. Maybe a flap is stuck open.

I guess ripping everything apart (if it came to that) wouldn't be such a bad idea. I'm trying to track down two squeaks and a rattle from inside the dashboard... man, these plastic mating surfaces are terrible.

We'll see what happens tomorrow. It's my day off .

iroc86 said:

Anyway, I was thinking about the issue and I'm convinced that the heater core isn't the problem. I've always gotten really hot air; it's the airflow that's disappointing.

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That definitely sounds like it could be the blower motor. however, make sure you have good vacuum all the way from the vacuum bottle (right behind the passenger side of the front bumper) to the HVAC controls. With the engine off, do you hear the doors 'whoosh' and move when changing the positions? That indicates whether the vacuum is holding or not. It's pretty common for the vacuum line to get holes in it as it passes under the battery though.

The other possibility is that the blower motor is toast...again it's a pretty simple fix.

ok guys and gals i am going to hop in here..hope you dont mind....

this morning was a chilly 32' so i went out 10 minutes before i had to leave for fire acadamy and started the heep up....when i left for the acad. the engine temp read a firm warm 210'..so i turned on the heater...from the point i turned it on in my driveway it blew cold air for another ten minutes, then finally it started to slowly come around...by the time i got to FA (25 minutes away) it was putting out air warm enough to cause me to turn down the heat...

thats the long end of it...does everybodies heater take that long to heat or what ,,my girls zj blows hot straight away from a cold start..which makes me think somethings wrong with mine?



thanks..

Maier

i know it's not nearly as cold here as it is where you are at, but it was in the upper 20's/low 30's here this morning. i let the xj warm up for under 5 minutes. by the time i drove probably 1/2 a mile, it was already pumping out warm air.