Why dont I have heat?

[ab_70chevy]

I'm not real good with AC and heat. My blower works fine, low, medium, and high, but the air blowing is not warm. It's on the cooler side but not cold. AC works kind of. I need a new compressor. But no warm air. Any suggestions on where to start looking?
Thanks fellas
-Andrew
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[TBONE1964]

A couple of things come time mind:

Is the coolant level OK?

How long do you let it run to check the heat? If the t-stat is stuck open it will take the engine a lot longer to get to operating temp. Also how is the engine temp? Is it at least 180 degrees?

You should have a vacuum operated heater control valve if your truck has AC. Is there a vacuum source hooked to it and does it work? Have you felt the heater hoses, in and out? Are they both the same temp or is one hot and one cool? If you are unsure about the heater control valve, remove it and run a straight hose from the heater core to the engine and see what happens. If you have one hot and one cool in this case, the heater core may be plugged

Is the cable for the heat door moving the heat door in it's complete motion? Sometimes the cables can get stretched and not move the heat door properly.


Make sure the above mentioned items are good and then we can see what needs to happen.

[Tom Vogel]

Try the simple things first. Coolant level, also check the heater valve to see that its opening and not plugged.

[68350]

If you turn ur controls to defrost do you get any kind of antifreeze smell or an antifreeze residue on the inside of your windshield? That's what happened in my 78 ford and the heater core was shot.
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[ab_70chevy]

Thanks for the info fellas. I'll look into it, and see what I can find out.
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[Drewski23]

Originally Posted by 68350

If you turn ur controls to defrost do you get any kind of antifreeze smell or an antifreeze residue on the inside of your windshield? That's what happened in my 78 ford and the heater core was shot.
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ive heard this mentioned before but why would a clogged heater core cause that? I havent experienced an anti freeze smell but i am re doing the heating system (it has never worked since i bought the truck) so i was just wondering

[SS Tim]

If you don't have a factory manual, download a copy here. There are lots of pages on the HVAC syatem.
http://67-72chevytrucks.com/vboard/s...d.php?t=558016

[68350]

My heater core was leaking it wasn't plugged.
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[PanelDeland]

Also check to see that the vac hose is good to the vac operated valve.

[ab_70chevy]

Ok, so both or my hoses are hot, both valves are opened as far as they will go, still no heat. Coolant level is to the top, and no kinks in the vacuum tube. Cables seem fine. Am I down to the heater core? Is there anything I can do to test it before I start ripping the dash apart to get to it?
Thanks again fellas-Andrew

[cdowns]

lots of times the housing that the heater core is in is clogged with 40years of crap and no air can flow accross the heater core causing no heat// remove blower moter and stick hand in hole and start by pulling out quite a few handfulls of really really disgusting stuff tjen with air or garden hose start flushing the rest

[Stocker]

It's starting to sound like a plugged heater core BUT if it's plugged, coolant wouldn't flow. Since both heater hoses are hot, coolant must be flowing through them. The hoses should get too hot to comfortably touch for the heater to work well. If they're not hot enough you may have a bad (or wrong, or missing) thermostat, or restricted flow (possibly caused by a partially plugged heater core).

[LockDoc]

-
Don't forget to clean the mouse nests out of your heater box...... That will probably cure your problem.

You have to tear it apart to do that, or at least pull the blower motor like Cliff said. I use a vacuum to clean the "Stuff" out of it instead of my hands though...

LockDoc

[mrein3]

Originally Posted by cdowns

lots of times the housing that the heater core is in is clogged with 40years of crap and no air can flow accross the heater core causing no heat// remove blower moter and stick hand in hole and start by pulling out quite a few handfulls of really really disgusting stuff tjen with air or garden hose start flushing the rest

Originally Posted by LockDoc

-
Don't forget to clean the mouse nests out of your heater box...... That will probably cure your problem.

You have to tear it apart to do that.

LockDoc

Either 40 years of leaves or a few days with a mouse will give you both heater hoses hot and no heat.

Plan a day to pull the box your heater core is in. Have Lysol and/or bleach handy in case its a mouse. If its leaves, get some screen material to put between your cowl panel and the opening under there.

[slikside]

Originally Posted by Drewski23

ive heard this mentioned before but why would a clogged heater core cause that? I havent experienced an anti freeze smell but i am re doing the heating system (it has never worked since i bought the truck) so i was just wondering

Just a plugged core prolly wouldn't cause this, but a leaking one certainly would. That's what I had. The fluid leaks into the plenum carrying the odors right into the cab.

[cdowns]

a heater core clogged with crap allows no flow of hot air as in no heat inside the cab of the truck/// and it is far more common cause of no heat than a ruptured leaking heater core

[ab_70chevy]

I have been driving around for a couple weeks with out a cowl panel, while I'm gettijg it ready for paint. Think that could be an issue?

[Avitech]

I just cleaned a mouse nest out of mine. That blocked almost all the heat and most of the airflow too.

[ab_70chevy]

Ok, so is replacing the heater core on and A/C truck the same as a non A/C truck? Iv never done one, so I really have no idea.

[ab_70chevy]

Also, do I need to take off the inner fender to do it? It looks as if I can't get to all the bolts.

[LockDoc]

Originally Posted by ab_70chevy

Ok, so is replacing the heater core on and A/C truck the same as a non A/C truck? Iv never done one, so I really have no idea.

I don't think so. The heater core on an AC truck is in the inside heater box and the non AC is in the outside heater box.

LockDoc

[LockDoc]

Originally Posted by ab_70chevy

Also, do I need to take off the inner fender to do it? It looks as if I can't get to all the bolts.

Read this old thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=223703

Read all the way through because some of it is for non AC units....

LockDoc

[cdowns]

how did you jump right to replacing the heater core???

from your initial post it sounds as if you have an air flow only problem and your heat solution is an easy no cost time only fix and you seem to b determined to try and throw money away by takin bad leaky advise????



is coolant level droping ?? smell of antifreeze?? a noticable leak at the core?? i did not see any of them symptoms listed????