toastyjosh

iTrader: (1)

So my heat has not been working, I gave a look at all of the hoses, figure i would replace my T-stat (which I have not done yet). So the truck runs warm upper part of temp guage up hill( this with it being 20F outside).
Then today I turned on the defrost and I had heat only to defrost. The vents blow ice cold air, WTF.
Anyone have any Ideas?

83

I'm guessing you know how your truck would usually work, and this is different, right? Because these trucks have a weird heat set up.

Could be your heater core is blocked, but if that's the case, you wouldn't be getting heat on defrost. If there is heat making it through to the heater core (there wouldn't be heat anywhere in the cab if it wasn't), then it must be that the little doors in the vents aren't working properly, so the heat isn't being directed to vents other than up by the windshield.

The side vents never blow heat. My lower vents (under the stereo) only blow heat on..."heat", maybe? Don't remember. I don't drive my truck much in the winter anymore. They blow cold on most settings.

Overheating, if you are getting coolant flow through your heater core (and you are, if you're getting heat on defrost), is from something which has nothing to do with no heat on other settings in the cab.

Common culprits are: thermostat, coolant (either old crappy coolant, or if you've been messing around in there lately, maybe there's air in the system), fan clutch, or a clog somewhere. Hopefully not head gasket.

When my truck was starting to overheat, I think it was my fan clutch. But while I was working on the cooling system, I figured I'd replace the thermostat and coolant, too. That solved the issue for me.

toastyjosh

iTrader: (1)

Ok thanks, so the side vents never blow heat, thats good to know. The Lower vents only blow cold.
(then it must be that the little doors in the vents aren't working properly, so the heat isn't being directed to vents other than up by the windshield. )
Ok I will look at these vent doors, not sure where they are. Thanks.

I have the T-stat and new cap ready to go its just damm cold out side. i hope that does it.

83

The lower vents only blow heat on certain settings. Really, your heat is mostly coming from the windshield vents. Just make sure there's actually a problem before you start digging into the heat ducting. I always have the lower vents turned towards the passenger side in the winter, since they're usually blowing cold air at me.

crazytexan

iTrader: (1)

Ha funny somebody mentioned this. I was trying to understand my heat setup today. When I got the truck I pulled all the heater controls out, (the fan never worked anywho), but trying to put those suckers back in...I was gettin pretty frustrated. So I decided to yank my AC duct out from under the dash and the heater vents by the floor board revealed Much insight on why I was having issues with the flaps not working.

The QUEEN!!!



And these are from ONE of the defrost ducts, and then the AC duct.


Now I'm wishing I diddn't pull out the AC ducts. What does the cab look like on the inside on trucks w.o AC? Or s this how everyones looks,



I pulled that whole bottom duct from the center vents, all the way to the driver side air vent. I need my heat working as well, or at LEAST defrost.

toastyjosh

iTrader: (1)

So did you get it back on?

I am still having the same problem, just found a bunch of leaves in the lower vents.
so there could be a bigger block down stream some where.
The other thing is when I use the heat setting on the slector switch I get nothing, just with defrost.

83

That's how the inside of my 78 looks. No AC.

thefatkid

If the vent blow straight back (side vent and below the radio) it only gets cool air. Its airflow direction bypasses the heater core. Well the side vents without a/c only get air from the cowel airflow. Heat will only come out of the defroster vents or the heater vent (foot vent).

toastyjosh

iTrader: (1)

Ok, so the vent below the radio, should let heat right? Or is the foot vent another vent?
Thanks

thefatkid

Below the radio is only cool/outside air, it bypasses the heater core. I don't remember on the roud eye trucks but mine says def and heat (floor vent) in red. Other setting are bylevel (a blend of cool vent air and hot foot vent air) and vent only shown in white.

83

Might well be that your vents are working correctly...

Now work on that overheating issue! Too much of that and bye-bye headgasket. Not something to wait too long to address.

Chickenman

I've got an 82. It only blows heat on the windshield and the feet. The other vents are cool air. I think that's how it's supposed to be

toastyjosh

iTrader: (1)

Well thanks guys, I guess my heat is working fine.
Mine does say heat in red, but just says heat no floor in there.
So good to know, i guess the heating system in the first gens is not that great.
Yes time to address the cooling system. I have a new cap and t-stat just need to man up and brave the cold.
Thanks

83

If those don't do it, think about replacing the coolant and fan clutch. Both easy jobs.

Yes, they didn't put a whole lot of thought into the cab heating system, in my opinion.

toastyjosh

iTrader: (1)

coolent is not that bad still dark green. i did add about a qt of it a few weeks ago.
The clutch fan, I never really thought about it. It does spin, does not make any noise, belts are all good.
Not to sure how to test it.

thefatkid

Just remember that your vent temperature at your feet should be around 150°. I just had to replace my heater core due to restriction. My hot air would loose temperature with higher fan speeds. On a 30° morning the cold inlet air was enough to offset any warm air the heater core would make and drop vent temperatures to 40°.

toastyjosh

iTrader: (1)

Ok, thanks. I will check that on the way home.
I do not really remember feeling any heat on my feet in the heat switch. Will check.
The other thing I have the vent to recurculate, hoping that the cold air would stop but no. The vent under the radio, when I turn the fan up it blows to the speed of the fan.
so i have hot air on the dash and cold ass air blowing at my hand. Wierd

suncomb1

Your Heater valve, vent control, etc. are controlled by color coded cables. Look at your heater valve and make sure the valve / cable moves when you change the position of the temperature lever on the dash. Under your dash at the heater there are cables connected to the various doors. Move the dash levers to various postions and observe whether the doors move. Make sure all of your cables are attached to their retainers otherwise the doors will not move properly.

toastyjosh

iTrader: (1)

Ok thanks I will check that.

On my ride home from work I started playing with the heat. With tab slid to dfrost, heat come out, cold comes out the vents.
With the tab on heat, heat comes out the floor vent thing, and not so cold air comes out the under radio vents.
When I switch back from vent to recurc, the warmer air is on the recirc setting.
I think it is working like it should, just not a great system.
I will crawl up under that thing tommorrow and start playing with levers.

suncomb1

If your system is working right it will roast you out of the cab. I have had my truck since new and it can roast me in the winter or freeze me in the summer. I run a 180 degree thermostat. Toyota first generation trucks have great oversized heating and cooling systems.