Hey Guys,

I have an '02 Durango with 115k miles on it. It has two problems I know of and I'm not sure if they are related or not.

1. The car quickly starts to overheats when we get stuck in traffic or sit in idle, like in a drive-through or at a long light, but once we get going it cools right back down.

- The car overheated around 80k and we had the radiator replaced, and then around 10k miles later overheated again but just ended up being a bad cap on the radiator.

2. The A/C (heat, defrosters or any option) only works on high. Nothing comes out on any of the other settings. This is only for the front the rear a/c works on all four power settings.

- The A/C is fairly cold when the car is going, but once we get stuck in traffic or have to idle it starts to come out fairly warm. I noticed this happening for a little while before it started to overheat too.

Let me know what you guys think is going on, and please ask any questions because I'm sure I left stuff out. By the way we pretty much always drive it with the air on (high only), but have to turn it off at lights and such to slow down the overheating.

Thanks,
Chris

 

First of all....Welcome aboard to the forum... Chris!!

1. Was your radiator TRULY replaced or the old one removed and repaired?

2. Did the repair facility back flush the system, as in drain the coolant and flush the system ending with new fresh coolant.

3. You didnt specify which engine you have. If you have 4.7 make sure the repair place did the burping procedure? Yes thats what is called....there is a allen screw by where the upper hose meets the block this set screw is to help remove air during the coolant servicing and future air pockets. Removing the air pockets is important for any coolant servicing procedures, but for some reason it is especially important on he 4.7

If those two steps were done, then move on.... other possibilities may include but not limited to thermostat, cooling fan clutch or possibly the electric fan relay. It is supposed to come on automatically with the air conditioning regardless of engine temp. It may supplement the engine driven fan during other times. Easy test is turn on the A/C with hood open and listen for the e-fan.

Thermostat: With 115K it is a good possibility of it failing. It should have been replaced with the radiator especially since it may have been on the lift and probably the easiest time to remove and replace it.


The fan only blowing high: Pretty easy, classic signs of the Blower motor resistor failing. About a $15 dollar part and about 5 minutes to remove/replace. Should be dealer stock, most of the newer ones are built with more ceramic coating on them so they last longer. While you have the resistor out check the wiring harness connections and check for melted wires, shorts, frays,etc..... You can r/r the resistor but it will probably fail again if you dont r/ the harness or possibly even the blower motor. Trust me I have replaced the harness twice.

FYI: When the resistor fails it usually fails to HIGH that way if it fails you have some sort of power to run defrost and air conditioning.

As for it warming up I am not sure but going to take a stab in the dark and go with blend door. When you are driving the A/C Compressor may have enough power to give it cool air but when stopped the warm air mixes and you get more warm.


All of thses items need to be attended too. You may not think about the fan but that fan not only controls the fan for A/C but the defrost speed and allows you to have the fan speed for windshield ice/rain/defrost for better visibility. You can see where the potential safety issue may come into play.

Thay may be related and depend on each other. IF the resistor fails AND you overheat the resistor may not work if it totally fails and you wont be able to turn the heat on to reduce the pressure off the cooling system and potentally overheat further and have more damage.

Welcome aboard again, someone else will post shortly.

 

ok the first thing i see wrong based on this information is that your electric fan is most likely not coming on, this would explain the warm a/c at idle/stop and at least part of the overheating, to check it you can turn the A/C on and look at it with a flashlight, its against the radiator in front of the clutch fan, be careful not to get in the way of the clutch fan. if the fan is spinning you have your problem, and the next step is to replace the fan relay in the PDC, and if that doesnt fix it you can check the fan by j umping it directly to the battery and if it still doesnt spin its time for a new fan.

the second thing is the blower motor resistor for the front fan needs to be replaced, as above, $15 part 5 min job to replace, will take you longer to walk into the dealer and buy it than it will to replace it.

and i would just like to point out to magic that the A/C system will shut off when internal pressure builds up to a certain point making your concern about the blower motor not running and causing more overheating b/c of more pressure is not an issue. also on the 01+ systems, if the fan stops spinning the a/c compressor goes off(or at least mine does)

 

I've been having the same issue for some time now. My electric fan was bad and I changed it. It helped quit a bit but my Durango still gets warm with the A/C on but not moving. Since then I've changed the water pump, thermostat, and cap and flushed and burped the system. The only thing left to do is change the fan clutch which seems to be fine. I have no reason to believe the radiator is clogged as I've owned my Durango since nearly new and have never used anything but properly mixed extended life coolant, no water or sealers of any kind.

 

Sharps, I meant the simultaneous failure of the Fan resistor causing no fan action and overheating. I know you can turn the temp select to full hot and that would send more heat through the heater core reducing pressure on the block and reducing temp but the fan speed on high should help it flow a lot better. I have had several vehicles in the past with heating problems, Im my younger days I got pretty proficient at this sort of "EMERGENCY PROCEDURE" to help bring the temp down. I just want to make sure I explained my theory correctly.

 

ok, i gotcha, i thought you meant the a/c condensor, lol my bad........

 

Sorry about that it is the 5.9.

The electric fan doesn't come on so I need to diagnose that further

Also the car overheated the other day when I was driving at good speeds which is a very new thing.

So bear with me now I don't really know what I am doing . The overflow is full, but the top pipe is empty. I added what I have left of my 50/50 to the top hose when it was running to see if I could see some flow but it wasn't enough to fill it up. Also at the point it was a little hot and steaming.

Also I honestly don't know about the radiator it was supposed to be new.

 

it kind of sounds to me like the hose that runs from the radiator cap to the overflow is clogged and only allowing fluid to flow one way (out of the system) then when it cools down air ends up in the system, my advice is to replace that small hose, and the radiator cap and you should be good to go (at least on the loosing coolant part)

 

Well I think your radiator is bad.

If you are sure the T-stat is OEM replacement part and working fine, the pump was replaced, and electric fan is good, washed out condenser and radiator fins with high pressure (hint), burped system, new cap, blah blah blah.

I would think the opposite way and go straight to the radiator or clutch fan. You can test the radiator using a laser thermometer and check for cold spots of check the clutch fan.

 

T-stat is bad and you need to fix your electric fan