No Heat

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jrjr

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Well your flow is restricted somehow.... with all that you have already done, I would think the pump may be the culprit. Either that or you have a restriction somewhere that only lets a little coolant trickle by....thus the flush suggestion. Flush again? Change pump? Both? Your call I guess.
 

Big Sarge

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I'll try the pump, gotta get new cats first and o2 sims so I don't throw codes but I'll let you know if the pump was it, thanks
 

SkyJumper

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I would not think it is the pump as it is hot to the touch at low fan speed. I would be looking at my HVAC control box. If you have hot to the touch but switch to hi flo and it gets cold, you may have a bad HVAC controller. In most cases it is in reverse of what you are experiencing. When hi fan flow it is hot but as soon as you lower the fan to low speed the air gets cold which is usually the blend door closing on you from the fan speed not able to hold it open at low. SO I would look at the HVAC controller.
 

SkyJumper

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HVAC is your dash heat and air controller, and the one on the center roof display. It may have a vacuum leak or a bad controller itself. You can pull it out of the dash and inspect the 3 or 4 hoses going into it, and or go to the local JY and get another one for like 5 bucks. Swap them out and see if this fixes your issue.
 

DualExpeditions

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On my 99 XLT, I could not adjust the temperature of the air when using the heater. I moved the temp knob back and forth - no change. I swapped knobs, and that fixed it. Bought some f-150 heater knobs off Ebay, changed the light color insert in the knob, mission accomplished.
 

panda24619

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check this tiny little vacuum line. its right behind the battery. it goes into the firewall. mine was broken. when i got my plugs done the guy fixed it for free. simple to do i guess. just cut it out and insert back into hole.
 

4cfed

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I'm having the same issue in my wife's 98 expy. but the weird thing is the knob turns hard about halfway to 3/4 way to hot.. in my 99 f150 the heat works veeery well and the knob turns free. The heat in the expy at full blast feels like the heat in my truck at half way which is where the knob starts getting hard to turn. I took some needle nose pliers and tried turning it with the knob off and no change. I was hoping maybe the hvac system was bad but then i called ford and about fainted when they told me what the price of a new one is! I have alot of tearing to do to get the issue fixed before winter. Anymore info then I've already read here then let me know thanks guys
 

GAINMOB

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I'm having the same issue in my wife's 98 expy. but the weird thing is the knob turns hard about halfway to 3/4 way to hot.. in my 99 f150 the heat works veeery well and the knob turns free. The heat in the expy at full blast feels like the heat in my truck at half way which is where the knob starts getting hard to turn. I took some needle nose pliers and tried turning it with the knob off and no change. I was hoping maybe the hvac system was bad but then i called ford and about fainted when they told me what the price of a new one is! I have alot of tearing to do to get the issue fixed before winter. Anymore info then I've already read here then let me know thanks guys

try changing radiator fluid...thermostat and whatever other advise they give you on this
 

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