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Heater Not Working. Where to start? 1994 B3000 v6


Research Rat

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So now that temps in the northeast are getting cold, I've tried using the heat in my 94 b3000 and it appears there isn't any (or at least much) warm air making it's way into the cabin. The controls on air/heat all appear to be working-ie air does make it's way out of the vents, but it's all cold/cooler air.

I can use some guidance on where to start troubleshooting.

Themostat switch in radiator
Heater core plugged?
Other?

Any tips on how to diagnose?

Thanks in advance.
-Scott
 


adsm08

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Start with coolant level. If that's ok, run it until it gets warm, then grab the heater hoses. If one is warmer than the other get a new core. If both are cool, then you have a bigger problem.
 

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Coolant level is good. I'll have to try the hoses next.

I was under the impression that having to replace the heater core was the worst case scenario??

-Scott

Start with coolant level. If that's ok, run it until it gets warm, then grab the heater hoses. If one is warmer than the other get a new core. If both are cool, then you have a bigger problem.
 

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Heatertreater.net

Its your blend door. The shaft has snapped, not allowing the air box to mix air prior to exiting into the vent system.

Your blend door is stuck in the cold position. Mine broke in the hot position which was lucky.

I used their product on my 97 ranger and it worked like a charm.

Great product
 

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I will 'second' the blend door suggestion. I had the exact same thing happen to my '97, and Heatertreater fixed it for me too. I'm not very mechanically inclined but didn't have too much trouble fixing this myself; took about 45 minutes. Garage was going to replace my heater box and charge me $500+. Mostly in labor since entire dash has to come off. Looks like this blend door issue plagues '93 - '97 Rangers, so yours would fall into this also. Go ahead and do an internet search on "ranger blend door problems" and you will see a ton of resutls. Good luck!
 

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Finnspin, VWRanger,
Thanks.

It sounds like the order of checking heater related elements.

Start truck: after reaching running temp check coolant lines in/out of heater core area. If return line is not warm, then no flow, and likely damaged core and thus replacement.

If the return line is warm, then there's an issue with the blend door or other.

On the Heatertreater site it recommended checking the temp control knob?

"The usual symptom is an inability to effectively control the temperature in your car. Note that this symptom can also be caused by a bad temp control knob, and this is a common failure on Ford trucks. Please check carefully before considering the blend door fix."

Any idea what this means?

Thanks.
-Scott
 

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You need to pull the motor off the top of the heater box. This is what actually turns your blend door when you turn the knob on the dash (temp control knob) between hot and cold. Once you pull it, you can reconnect the wires/power to it. Then turn the knob on the dash (with key turned on so there is power) and make sure the motor is working - it should turn as you move the knob. If it doesn't turn, could be a bad motor or wiring. Otherwise, it's the blend door.
 

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vwRanger

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It looks like your bottom slider is doing the same thing as the "temp control knob" on my '97. I didn't notice any noises when I moved the knob between hot and cold either. So i don't know that you can use that as an indication. Not sure where it is located on a '94, but on my '97 I fully dropped the glove box and could see the heater box with the motor on top. As noted in the HeaterTreater specs, the motor could be mounted to the top of the box with either screws or plastic snaps. Mine had the snaps and was fairly easy to remove and determine whether the knob/motor was actually working. Yours may be attached via screws which according to the specs is a little more difficult to remove (due to the limited space).
 

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Coolant level is good. I'll have to try the hoses next.

I was under the impression that having to replace the heater core was the worst case scenario??

-Scott
Not really. A plugged core can be unplugged. Just takes a garden hose.
 

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I'm not a daily driver, so just got around to checking the coolant temp lines.

I popped the hood, started the truck, and let it idle for a few minutes. Coolant lines into the firewall remained cold after a few minutes. Does this indicate the thermostat is working?

I drove for a few miles (probably 10 minutes in stop and go traffic.) Popped the hood, and both coolant lines to the firewall were warm to the touch and surging. So coolant is flowing in and out of heater core?

Outside temps were in high 20s,and when I turned the heater on, nothing but cold air! Argh.

Is there any other troubleshooting that I should do or is my next step ordering the heater treater kit?

-Scott


Finnspin, VWRanger,
Thanks.

It sounds like the order of checking heater related elements.

Start truck: after reaching running temp check coolant lines in/out of heater core area. If return line is not warm, then no flow, and likely damaged core and thus replacement.

If the return line is warm, then there's an issue with the blend door or other.

On the Heatertreater site it recommended checking the temp control knob?

"The usual symptom is an inability to effectively control the temperature in your car. Note that this symptom can also be caused by a bad temp control knob, and this is a common failure on Ford trucks. Please check carefully before considering the blend door fix."

Any idea what this means?

Thanks.
-Scott
 

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