1998 Durango with a Cool Heater

[atamians]

I have a 98 Durango with a heater that never quite gets hot

1. Engine Temp is good
2. Heater on with MAX A/C selected is pretty good
3. Hot air is not bad above 30 degrees
4. Below 30 you need to wear a jacket.
5. Coolant level is good.


I'm guessing this may be vacuum related because the temp gets better with the selector on MAX A/C.

On some hills the mechanism that diverts air from the dash vents to the defrost vents changes state until the engine load resumes a normal state.

Any thoughts?

Chris

[Benzman]

Chris, I'm having an identical issue.
I'm hoping that you have solved this problem and can point me in the right direction.
I too am thinking that it is the air diverter, but don't really want to tear into it too badly.

[creslevi]

Both you guys need to check for a vacuum leak, if it changes condition under a load.

[dirtdriver11]

I had the same problem on a 99, I just swapped the heater hoses that go to the heater core and it made a big difference in the heat. It's worth a shot, but becareful not to bend the fittings on the heater core.

[cglenn1045]

Hey,

I have a 2000 durango that had the same issue. I replaced the thermostat and flushed everything. Believe it or not the answer was right in the manual. There is only one heating setting and that is the indicator that has the full body with the arrow pointing to the feet only. All other settings including MAX A/C, the air is directed via the heater control valve thru the A/C path and not across the Heater Core. Hope this makes sense, but now i am sweating in my truck now.

[Benzman]

You are correct that all settings except the feet only run the A/C compressor.
However, my problem does appear to be vacuum related.

Symptoms: Heat is acceptable at 35F or higher outside temperature, below that the air stream from the feet vents are cold unless I am accelerating then it becomes moderately warm. However, the air stream from the defrosters is pretty warm regardless of engine load.

The strange thing is that the air mix door is cable operated, not vacuum, or at least I thought it was.

I bought a mityvac from autozone yesterday, so now I can start troubleshooting. The vacuum diagram shows 3 solenoids, 2 of which are labled. One labled floor/defrost, one labled panel/defrost, and a 3rd which is not labled. Can anyone help me to determine the purpose of the 3rd solenoid, and maybe where it is located?

[Benzman]

OK, so I leak tested the vacuum to everything except the brake booster. The system held steady at 18hg for 10 minutes. Then when I came back 4 hours later, it was still at 15.5. So, it's not a leak.
Question: Does anyone know what the propper vacuum is immediately off the engine? I'm getting 15 at idle, but I have now idea what it should be.

[bwolfden65]

These problems seem very similer to my 98 Durango.

1. little to no heat
2. cannot get engine temperture to rise (stays @130 -140)
3. have already flushed cooling system
4. have had a "blow-back" performed
5. heater core not leaking

note: after a really long distance (30 miles) it might raise up to 170 degrees.

My wife calls it "the blue iceberg".

What is the right degree thermostat, and I did use a 50/50 premix solution.

Any thoughts?????

[Benzman]

Originally Posted by bwolfden65

2. cannot get engine temperture to rise (stays @130 -140)

Your problem actually sounds like a bad thermostat. I'd replace it, temperature isn't critical, 180 to 195, anywhere in there.

[bwolfden65]

Originally Posted by Benzman

Your problem actually sounds like a bad thermostat. I'd replace it, temperature isn't critical, 180 to 195, anywhere in there.

You're thinking that the thermostat is stuck open, therefore cooling too much. Actually, after letting it idle for 20 min, then driving, when I pop the hood, it still has a hard hose, telling me it's closed. Doesn't make sense to me. If it is closed, wouldn't the block overheat? Opening the rad cap shows no flow of coolant.

[Benzman]

Maybe the thermostat is just weak, allowing the thermostat to open at a lower temperature, i.e. 130-140.

I guess it's also possible that your fan clutch is bad, causing the fan to run 100% of the time, keeping things cooler than should be.

One more thing, maybe the temp sensing unit is bad, sending a temp of 130-140 to the gague, when in actuality, its higher. You could verify that with a good thermometer, or infrared if you have access to one.

[bwolfden65]

Originally Posted by Benzman

Maybe the thermostat is just weak, allowing the thermostat to open at a lower temperature, i.e. 130-140.

I guess it's also possible that your fan clutch is bad, causing the fan to run 100% of the time, keeping things cooling than should be.

One more thing, maybe the temp sensing unit is bad, sending a temp of 130-140 to the gague, when in actuality, its higher. You could verify that with a good thermometer, or infrared if you have access to one.

Very good points,...I will investigate them. Meanwhile, I'll buy my wife a scarf for the "Blue Iceberg"!!

[Webslinger_94]

I am having the same problem with my 98 as you guys, but there is one thing in my durango that leads me to believe that its time to replace the heater core. When I turn on the heat I get a sort of maple syrup smell (if you know what I mean)

[dss56]

I had the same problem when I bought my 98 durango 4 yrs ago. I would be on the highway and the heat would do funny things like change the air direction under a load going up a hill and you could hear the fan but no air.
This is what I found. Behind the Tranny check stick near the passenger firewall they have a T vacuum fitting that rubs against the tube and firewall. I found it to have rubbed so much that it wore a hole in it. I went to dealer because there are different sizes for hoses to connect and something funky about that I had to order from dealer. Any ways that was the vacuum leak I had and it cured the problem. Funny thing is you could not hear the leak but enough to screw things up. I also remember that one line was connected to the brake booster.

Good luck

[firehawk_14]

i have a 99 derango and the temp goes over have way i changed the thermastate and flush and it still goes high what would it be ????????