phorunninduke

I hate admitting defeat but I might have to concede to my truck and get used to the frost and cold....

Since I have purchessed this thing the heater has never put out hot air. Every part of the cooling system as been replaced from the radiator to the heater valve, lines, and core. I have checked and resealed every part of the venting system, ( so at least the air is blowing out of the right vents ). The heater core and its lines will get very hot, too hot to touch actually, but the air that comes out the defroster vents is barely above ambeint. The coolant tempature is normal and the thermostat is fine. I don't feel any leaks in the duct work.



It's cold here today too.... so help me out.

edit: Funny there is about 3 other heater/heater core related post on the first page today. Mine is still unique because it is all new core and radiator all the flaps and ducts work. Some how the heater core is hot but the air comming through isn't/

rugerm44

What year is it?What model is it?

waskillywabbit

iTrader: (-1)

I ride in one w/ an open back and no heater...buy a warmer jacket and some gloves!

Sounds like the air isn't being directed through the heater to get warmed...you are just blowing ambient air so some flap somewhere ain't closing like it should.

Glenn

I had a problem like that once on my previous truck. The slider that operated the heater wasn't sliding the cable that controlled the valves by the heater core. I fixed it by taking the slider assembly out and fixing it. What kind of control do you have--a slider or a rotary dial?

CoedNaked

Sure there isn't a "flapper" or something blocked in the dash somewhere that would open to let heat through? I've heard stories and actually saw one instance (on a Ford though) where a pencil went down the vent and lodged it shut.

phorunninduke

Thanks guys,

I have fixed the cables and checked the flaps, in fact I can litterally stick one hand on each side of the heater core and feel the air moving through.

Good idea wabbit on the jacket, but I like the defrost feature to work none the less.

Wes Gardner

OK, after just building a heater for my boat and running in new rubber lines on my 2nd gen., heaters and me seem to get on OK...so here's the logic - IF the core is HOT, then it's either a fan not blowing THRU the core (at full velocity) or a duct issue allowing air to go where you don't want it...can't really be anything else. Don't know but CAN the water lines be getting hot but in actuality not allowing water flow thru the core thus, when the fan blows, the core really isn't hot thruout? I know my lines up near my firewall were all pretty hot just due to proximity to the motor - I really didn'tr investigate any further as I figured out pretty quickly that my problem was UNDER the vehicle (mine was the aft heater)

What had blocked my aft heater was CRUD in the small metal lines leading back there...I was getting NO heat from the heater...maybe your core is partially blocked? Don't know how much of a PITA getting the forward core out will be but I'm certain there are others here on the forum who've done it?

What made me think of the partially blocked deal is I'm not getting alot of heat from the core in my boat...it's probably where I tapped the block to get the hot water...

Wes

phorunninduke

The heater core is brand new, and deffinatly not bocked. There is air comming through the vents, so it is not a blower probelm. As far as I can tell the ducting and flaps are operational.
For some reason I get the feeling my truck is just in between some weirdo dementions where the laws of physics, specifically dealing with disperation of heat, do not apply.

Wes Gardner

So you said you can actually stick your hand on either side and feel the air...so the air isn't warm...guess not, so does that mean the core isn't warming the air, guess so...so can that mean the water circulating thru the core isn't of adequate temperature? definite maybe. Maybe the water valve isn't fully opening? T-stat allowing too much flow? Hey, I'm guessing too...

I assume you've rules OUT the duct system...maybe some sort of air lock in the core? It seems years ago a similar problem happened to me but I think I sold th truck before resolution...sorry....


Wes

phorunninduke

Yeah, thanks Wes. At least I know I am not crazy. My current therory is cool air from the cab is getting into the vent system somewhere.

wonderbread

hey phorunninduke. Im up against a similar problem with my 98 2.7 4x4. I have replaced; radiator, heater core, thermostat, controll valve, etc. all new. I even flushed the entire cooling system frontwards and backwards, twice. And im still getting weak heat. Im wondering if this is an inherant prob. with the 4runner. My 94 Toy P/U 2.4 blows hotter that sin. Do you know if the front and rear cores run in series? Or do they have independent lines in and out?

leebee

front and rear heaters are separate.

lee

Flamedx4

Wow, that's a good one.
If the cab air could get into the system it would only do it before the blower (therefore before the core) since after the blower the air system is pressurized.
If the inside/outside damper was open all the time, it wouldn't matter. It should be open anyway on all settings (except max AC,) so that's out.
The heater should be able to manage fine even with the AC on, so that's out.
But I think it's a blend-air type system, the blend damper may not be closing properly. This seems like a likely culprit.
I think you said the air coming right out of the core is hot but when it gets to the defrost vents it's no longer hot? That isn't logical, the air certainly should not have time to cool off in the duct system. We know the duct system 'should' work - it works on hundreds of thousands of others.... I assume you have investigated the duct system and not found anything wierd with it, although unless it has a big refrigerator in it that's not likely the problem. Even if it has holes letting air out in the wrong places, the air that makes it through to the defrost ducts would still be hot. (But a tight system without air leaks works better..)

I would suggest borrowing a point-n-shoot thermometer and a probe type (kitchen thermometer.) See what temperature the coolant at the inlet and outlet sides of the core REALLY are. That may tell you something. See what the temperatures are on the heater valve lines too. See what temperatures the air really is at the inlet and exits - all of them, floor, face, defroster.
Some random thoughts-
Did you do something like repaint the new core?
Is there a filter (cabin air filter) for the system? Is it installed?
Are you sure you waited long enough for the core to get hot? (had to ask) And for the ducts to warm up?
Is it possible that the coolant is flowing through the core so fast that it's not transferring heat?
Is it possible that the air is flowing through the core so fast that's not accepting heat? (hence the question about the filter)
I believe the water valve is a simple flow valve, not an H-valve with a return. So it's simple to adjust the cable and to check with a thermometer to see if it's really passing coolant.

My best guesses would be the heater valve, and the air blend door (the "air mix control damper")

Flamedx4

WAIT! I'VE GOT IT!
You have my GF in there! Her feet are always So &%$#&* Cold, poor heater doesn't stand a chance....

Wes Gardner

Do we need pics of said GF to fully assess the situation?


Wes

Flamedx4

If any of you who know me tell her, she'll kill me...
(photo cropped just in case...) Not bad for a grandmother!

Meet the future Mrs. Flamed:

phorunninduke

I think i would have noticed her and/or her feet in my truck.

My line of thinking was very similar flamed, I have not made any real progress on this situation however. I beleive the air tempature is warm, but if feels cold. Kinda like my fish tank in the winter, the water is at 80degree F but it feals cold when you stick your hand in.

Corbit

I have the same problem , my girl freinds feet are always cold . But really I have flushed my heater core and radiator , changed T-stat and heater switch on the fire wall as well as topped off coollant. I get warm heat for a couple of seconds then just cool air.
The warmer jacket works for me but not my rug rats, and my girlfreind wont even think of getting in.

Flamedx4

I did some checking on mine after I drove home from work (my heater will cook chicken!) I can't get at the core easily, but the hoses going thru the firewall will do. I used a meat thermometer in the vents and a pointandshoot thermometer on the hoses.
Blower on 3 of 4. Heater slide all the way to Hot. Engine idling. Recirc off.
Outside air temp - 39*
Engine coolant temp - 188*
Temp going into firewall - 177*
Temp coming out of firewall - 142*
Ambient air in cab - 65* (72* at end of test)
Air from dash vents (on Vent) - 109*
Air from floor vents - (on Floor) 111*
Air from defrost vents - (on Floor/ Defrost, my normal setting 90% of the time) - 99*
Air from defrost vents - (on Defrost only) - 102*
Air from defrost vents - (on Defrost w/ AC) - 96*

Hey! What coolant mix you running? Straight water or straight antifreeze (for example) don't exchange heat very well, will effect the heater temps as well as the radiator effeciency. Just a thought.