Little to no heat from heater

My wife's 90' Laredo's heater really sucks...It can be running on heat for a good 15-20 minutes and still it doesn't warm up... any ideas what could be wrong with it?

In my 87' chief I can turn the defrost on in the morning and it's nice and toasty within 5 minutes.

Thanks

Sounds like the heater core is plugged up.

i would check the heater valve to make sure its operating properly, and check the blend door on the underside of the dash on the passenger side (it has a cable going to it) and make sure the door is opening and closing when you move the lever from cool to heat. the cable snapped on my 95 and to go from heat to AC i now have to lean over and move the arm on the door by hand.

hope this helps

You don't say if engine temp gage shows hot or not. If it does, feel both the heater hoses. They should both be hot. If not, heater core blockage (flush) or valve not working. (I think yours still has the inline water valve.) If engine not getting warm, probable thermostat issue. If gage hot and heater lines hot, check blend (temp) door operation on housing under dash.

winterbeater said:

You don't say if engine temp gage shows hot or not. If it does, feel both the heater hoses. They should both be hot. If not, heater core blockage (flush) or valve not working. (I think yours still has the inline water valve.) If engine not getting warm, probable thermostat issue. If gage hot and heater lines hot, check blend (temp) door operation on housing under dash.

Click to expand...

good points!

the heat in my 95 sucked for a winter. turned out to be a thermastat stuck open. it kept the engine from reaching operating temps, gas mileage sucked, and the heater was luke-warm at best.

a new t-stat, and cooling system flush had me cooked out of my heep in no time.

the heat on my 86 was sucking eggs this winter. It turns out there's a little vacuum operated valve on the hose leading to the heater core that had ceased operating. I removed it, problem solved. Good luck, a hot jeep makes all the difference in the winter!

same thing happened to mine....did you just take it off alltogether? i just put it in the open position manually


and i think i need a new tsat too i cant get the heep above the first line on the temp gauge, also it hsnt broken 20 here recently so that may be a factor

How would I unplug a plugged heater core if that is indeed the issue? Would that be in my Chilton's as far as where to locate it? I'm still new to doing my own work...

And as far as operating temperature, the engine does heat up, temp gaug gets up where it's supposed to...The heater just sucks. I'm hoping it's an easy fix though.

Disconnect heater hoses at end opposite from heater core. And run water into the hose that comes from the water pump until it get clean coming out of where it was attached to the thermostat housing. Then flush the other way too just for good measure. Recover used antifreeze for reusal or proper disposal. It is very toxic to animals and they are attracted to it like soda pop.

Or cut both lines and put "tees" in to achieve same effect.

yeah i know what your talking about. I was totally clueless only a short time ago, and spent ages searching for the really basic stuff. Much of it didnt help because of my own REALLY LOW level of knowledge, so ive put some pictures in (hopefully) to possibly help




This is the top heater hose that you need to disconnect.




this is the bottom heater hose that you need to disconnect. Both connections are probably really tight. Once the connections are off, spray garden hose water into one towards the engine firewall and watch the water come out the end of the other hose and just keep alternating between the two. Not too much pressure, but you do need to have some pressure in there to get it cleaned out. once the water starts to run clear, just leave it for a while! be patient with it, then swap to the other hose then back again. I flushed mine but didnt have enough pressure in there so still didnt have proper decent heat. Better but not decent, so i done it again using more pressure from the garden hose and also i blew in the hoses. A load more gunk came out. Personally i think that two tpieces is easier on each heater hose like this

(Ignore the hoses coming down. thats for a gas system.)

but as you can see its handy because you just have to undo the t-pieces without any harm of damaging the stupid metal arm that connects to the water pump. Shoot water in both these hoses towards the cab, alternate between the two, blow in each hose to get the stuff out and eventually you will get there if your lucky. But apparently too much garden hose pressure will end up being very expensive as it could burst a hole in the heater matrix which is what your trying to clear out.

A Prestone power flush kit includes the t's, flush, and clamps to do the job for the whole system. But on a '90 - prepare to R&R the core. After 17 years they have too many deposits. If you loosen them well, it may start leaking. Heater cores are just small radiators, they just go bad after a while. A new heater core is a bother to change out - you pull just about the entire dash, but you can seal up air leaks, service the vac hoses and cables, grease pivots on flap doors, etc. It can be a real tuneup that lasts another 17 years.

Thnx about the T-stat, mine won't warm up at all either.

Dunbad -

That is one sanitary engine compartment.
Nice.

Steve

yeah its real nice considering its never been steamed cleaned. Just 30k on the clock helps though! even if its still only a 97!