No heat again!!! Grrrrr
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No heat again!!! Grrrrr
hey guys i have not been on here in a long time but im having all kinds of heat issues with my truck again. i just started to use heat again about a month ago since its been getting cold here in NY. well it didnt work lol. so i flushed heater core topped off coolant and it worked again for about a week or two. then the truck started overheating and no heat again. so i replaced the tstat first. still overheating and no heat. then replaced clutch fan. still overheating and no heat. bought a new radiator, rad cap and water pump and serp belt. replaced all fluids, flushed heater core again and flushed system. truck ran perfect again and heat was back FOR 1 DAY!!! this was on black friday 2 days ago. now the truck has no heat again but is running like it should and not overheating. so now im convinced it must be the heater core is shot. when i first turn the heat on it blows hot for about 5 seconds then goes cold again. i know to do the heater core or the blend door in theses trucks is a 10hour job or so since you have to remove the entire dash. also i know these trucks need chrysler specific coolant but i was told over and over again i can use the Peak 50\50 because it has the same additives as the chryseler coolant reccomends so thats what i used. i have done so much research on this topic and ive tried everything except the heater core, i know its not the blend door. has anyone replaced this, and does it really take that long. searching this topic is such a headache, never any straight answers. please help!!
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Not sure what to say, but my understanding is if both hoses to heater core are hot, the coolant is circulating through the heater core. So my next thought is something wrong with the blend door. May explain why it is hot for a few secs then gets cold again. The only time I think it would be the core stopped up etc is when only one hose gets hot. So doesn't sound like heater core to me.
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Joined: Dec 2011
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From: Chicago suburbs
First check the recirc/fresh air door, which is up behind the glove box. You will be able to visually see that damper open to recirc., with the glove box removed. (it clips in)
On a single temp control truck, (which I have, an 02 sport 4.7) the blend door(s) are a pair of dampers linked together, driven by 1 motor. This damper is roughly behind the cup holder, towards the passenger side. You should be kinda able to see the actuator operate, with the cup holder out, (about 4 or 5 screws) with the dash intact. If that actuator moves, AND both your heater core hoses are hot, issue is most likely the doors themselves.
That will involve removing the HVAC box. This is a long process, documented here in the Ram section, in the Durango / Dakota section, & you tube.
There are after market doors / kits available that may exceed OEM quality.
And, now that you are in the box, might as well change out the heater and a/c cores.
It's supposed to warm up this weekend. I think I'll have to do my heater core.
On a single temp control truck, (which I have, an 02 sport 4.7) the blend door(s) are a pair of dampers linked together, driven by 1 motor. This damper is roughly behind the cup holder, towards the passenger side. You should be kinda able to see the actuator operate, with the cup holder out, (about 4 or 5 screws) with the dash intact. If that actuator moves, AND both your heater core hoses are hot, issue is most likely the doors themselves.
That will involve removing the HVAC box. This is a long process, documented here in the Ram section, in the Durango / Dakota section, & you tube.
There are after market doors / kits available that may exceed OEM quality.
And, now that you are in the box, might as well change out the heater and a/c cores.
It's supposed to warm up this weekend. I think I'll have to do my heater core.
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Not sure what to say, but my understanding is if both hoses to heater core are hot, the coolant is circulating through the heater core. So my next thought is something wrong with the blend door. May explain why it is hot for a few secs then gets cold again. The only time I think it would be the core stopped up etc is when only one hose gets hot. So doesn't sound like heater core to me.
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Thread Starter
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Rookie
Joined: May 2010
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First check the recirc/fresh air door, which is up behind the glove box. You will be able to visually see that damper open to recirc., with the glove box removed. (it clips in)
On a single temp control truck, (which I have, an 02 sport 4.7) the blend door(s) are a pair of dampers linked together, driven by 1 motor. This damper is roughly behind the cup holder, towards the passenger side. You should be kinda able to see the actuator operate, with the cup holder out, (about 4 or 5 screws) with the dash intact. If that actuator moves, AND both your heater core hoses are hot, issue is most likely the doors themselves.
That will involve removing the HVAC box. This is a long process, documented here in the Ram section, in the Durango / Dakota section, & you tube.
There are after market doors / kits available that may exceed OEM quality.
And, now that you are in the box, might as well change out the heater and a/c cores.
It's supposed to warm up this weekend. I think I'll have to do my heater core.
On a single temp control truck, (which I have, an 02 sport 4.7) the blend door(s) are a pair of dampers linked together, driven by 1 motor. This damper is roughly behind the cup holder, towards the passenger side. You should be kinda able to see the actuator operate, with the cup holder out, (about 4 or 5 screws) with the dash intact. If that actuator moves, AND both your heater core hoses are hot, issue is most likely the doors themselves.
That will involve removing the HVAC box. This is a long process, documented here in the Ram section, in the Durango / Dakota section, & you tube.
There are after market doors / kits available that may exceed OEM quality.
And, now that you are in the box, might as well change out the heater and a/c cores.
It's supposed to warm up this weekend. I think I'll have to do my heater core.
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Joined: Nov 2012
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I'm not saying the other suggestions are wrong because the blend door is most definitely a possibility with our trucks. I too have an '02 with the 4.7 and I too was having the same heat issues described here. Little to no heat with the fan on position 1 and even less the the fan running at higher speeds.
I did the coolant system flush and I also disconnected the hoses to do the radiator, motor and heater core individually. Installed a new 180 thermostat after verifying it worked properly and had heat for a short period of time but it faded out again.
Long story short, I read up on all the possibilities and one by one eliminated them. Turns out that even though I had used the vent screw on the motor to vent the air out it still left some in the heater core.
I had grabbed the heater hoses after driving home from work and they were both hot, it wasn't until I checked them with an infra red thermometer that I found that the inlet hose was at 180 degrees and the outlet was at 120/130 degrees. This was checked with the fan off. That's too much of a difference and told me I wasn't getting the flow I needed.
I temporarily installed a flushing tee from a kit into the outlet hose and used a small low volume transfer pump to force anti-freeze into the core. There was air trapped in the core because the level in the reservoir dropped almost 1/4". I've had great heat now for about two weeks. The inlet side is still at 180 degrees and the outlet side with the fan on the highest setting is at 150 degrees.
You may be tempted to leave the tee in for future use but it is plastic and didn't look like it was made all that well, take it back out. I didn't want to drain the cooling system so I used quick clamps to pinch off the hoses.
I have a write up with pictures if anyone's interested, if I can post it with so few posts here.
Take care.
Don
I did the coolant system flush and I also disconnected the hoses to do the radiator, motor and heater core individually. Installed a new 180 thermostat after verifying it worked properly and had heat for a short period of time but it faded out again.
Long story short, I read up on all the possibilities and one by one eliminated them. Turns out that even though I had used the vent screw on the motor to vent the air out it still left some in the heater core.
I had grabbed the heater hoses after driving home from work and they were both hot, it wasn't until I checked them with an infra red thermometer that I found that the inlet hose was at 180 degrees and the outlet was at 120/130 degrees. This was checked with the fan off. That's too much of a difference and told me I wasn't getting the flow I needed.
I temporarily installed a flushing tee from a kit into the outlet hose and used a small low volume transfer pump to force anti-freeze into the core. There was air trapped in the core because the level in the reservoir dropped almost 1/4". I've had great heat now for about two weeks. The inlet side is still at 180 degrees and the outlet side with the fan on the highest setting is at 150 degrees.
You may be tempted to leave the tee in for future use but it is plastic and didn't look like it was made all that well, take it back out. I didn't want to drain the cooling system so I used quick clamps to pinch off the hoses.
I have a write up with pictures if anyone's interested, if I can post it with so few posts here.
Take care.
Don