why does my heater not heat?

[zturnidge]

hello my name is zack i just got a sweet van! 85 le. we love it but i have a few questions. first off where is all the cold air coming from under the dash and why wont the heat get very hot? if i have the heater on low the air is pretty warm but the higher i turn the fan the cooler it gets. any help would be great!
also how do i get the rear heater to even turn on?


so i pulled out the heater controls sure enough the temp control part is broken. i got the cables adjusted to where they should be. much better but now it will be really warm at first the it cools down i messed with the controler under the vanseems to be working but noticed that of the 2 hoses coming from the heatercore one is hot and seems to have pressure but the other is just the opposite.
please help. it gets pretty cold in utah!

[llamavan]

Welcome, Zack!

Checking the control cables is a good first step, although finding one heater hose warm and the other not suggests to me that the heat control (blue) cable isn't really fully "on"; this is a common result as the vans age and acquire some corrosion on the cables. You can find instructions on lubing the van cables in this thread.

What does the engine temp gauge on the dash read after the van has settled into a "normal" running temp? MOST vans run about 40-45% on the gauge. There are notable exceptions (I own one of 'em — reading 25% is actually the normal operating temp for him), but if the needle doesn't rise very much, the thermostat is sticking/stuck open and needs to be replaced (which, in turn, will increase the available heat for the cabin). Thermostat replacement is covered here.

The rear heater is controlled entirely from the control panel to the left of the rear middle seat (above the battery access).

Gwen

[zturnidge]

that is very helpful thank you!
i was even moving the temp controller underneath manually. the hose that goes into the control valve is hot on both sides of the valve it seems. but the other hose is cold.
the temp gauge hardly moves up at all id say like 15% maybe 20 max. i guess i should check the thermostat then?

[llamavan]

I would DEFINITELY replace the t-stat. You have nothing to lose!

IME, when the cabin heat is weeny to begin with, using the fan sucks the heat right out (the higher the setting, the faster the heater core cools off). Makes sense — that's the point of having a fan for the radiator (additional air flow cools the coolant). And, of course, heat dissipates from the coolant in the heater core, just like in the rad, because it's designed to do just that.

Not having another van to compare to means having "warm" hoses on both sides of the valve only says the valve is now open.

Hopefully the t-stat solves the problem and you find out the true meaning of "hot" hoses. If not, backflushing the heater core comes next. However, a plugged up heater core is a relatively uncommon problem in the vans, which is why I'm not suggesting that first ... unless the van has a history of plugging up multiple radiators (which are far more prone to collecting deposits, thanks to year-round use, a larger inlet hose and the law of gravity).

Gwen

[zturnidge]

awesome thanks!

i notice your from eugeneish. we just pick this van up in cottage grove, just south of eugene. random i guess.
anyway ill prob do the tstat as soon as i can get one.

[fuquan]

Hi Gwen and All -

I also have this problem of weak heat, particularly in the front. It's now very cold in the Northern US and I really have to bundle up when I drive. When my blower is on level 1 or 2 an acceptable temperature heat comes out of the vents. When I turn the blower up, the air cools way down. My rear heat, on the other hand, is not too bad even when I turn the blower to the highest setting. However, I feel that even that should also be hotter.

When I bought the van it had poor heat and the engine was running really hot (needle approaching the red). I had the entire cooling system replaced. Toyota t-stat, recored radiator, water pump, fan clutch, hoses, cap. Now my heat gauge maxes out at ~50% In the process of getting the new cooling system, and a lot of other work, my mechanic removed the front heater core and flushed it. It was reported to be OK.

I have removed both heater dash cables in order to manually [fully] open the air box valve/flap (where black cable ends under dash) and the coolant damper valve (where the blue cable ends under the front of the van).

I can feel heat in both hoses going into the front heater core. So I know heat is getting through the core. How hot should those hoses be? Is there a way to measure the temperature of my coolant when the engine is running? When I reach under the dash to touch the bottom of the heater core it feels pretty hot.

Could there be something wrong with the air mixer box (end of black cable)? Sorry, I don't know the right word for that, but I imagine it to be a plastic box with flaps that routes and/or mixes outside and inside air.

If coolant is flowing through the heater core, what could be the cause of weak heat?

Thanks for any thoughts.

I would DEFINITELY replace the t-stat. You have nothing to lose!

IME, when the cabin heat is weeny to begin with, using the fan sucks the heat right out (the higher the setting, the faster the heater core cools off). Makes sense — that's the point of having a fan for the radiator (additional air flow cools the coolant). And, of course, heat dissipates from the coolant in the heater core, just like in the rad, because it's designed to do just that.

Gwen