Cooling & Heating Issue

[Adi Barry]

2008 EDGE 2WD Limited with tow package (V6)

 

I have already: had coolant flushed (changed thermostat at the same time), replaced entire fan assembly including fan module control, checked fuses (no relay).

 

Symptoms: heater blows cold. Thought thermostat was sticking Off/on at first because it overheated just for a moment then went back to normal. After changing thermostat, heater worked for about a day, then the car overheated again, and heater started blowing cold.

 

Figured Out fans weren't turning on (tested by hot wiring). Just put new assembly in today (was very easy, btw!) and fans aren't staying on consistently. It's worth noting before completely going out, previous fans were intermittently going out also. Had to put the car in neutral (or pull over if possible) and turn the ignition off/on a few times to get them to turn on.

 

Other things that can affect the fans turning on: CHT Sensor which goes to the PCM, and another cord goes from PCM to Fan Control Module. However, I don't think either of these would impact the heater right?

As far as I can tell, since changing the fans the only time they don't turn on as they're supposed to is on initial cold start. Once the engine starts to get hot & I turn it off (usually leave the heater blowing without the engine on for a few), I can turn it back on and fans kick on right away. Because I had to work today, this has only happened twice. Every other time I've started it, the engine was already somewhat warm and there was no problem.

 

Maybe there are 2 separate issues happening by coincidence? A friend of mine thinks there may be an air bubble from when the coolant was flushed. Tomorrow morning I also plan to watch it as it warms up on the first start (so I'm ready if it over heats) to test the plug going to the fan control module. Once it's warm, gonna try to check the hoses to/from the heater core to be sure it's not clogged. Same friend Also said he had similar problems a while back on a different vehicle & ended up having to replace the radiator. Any easy way to test that?

[WWWPerfA_ZN0W]

Did you check for codes to see if any are set? Codes do not necessarily trip the CEL. Do you have the electronic or the manual climate control?

 

I don't think there's anything the matter with the fans/module from what you have described. The fans are not supposed to kick on until after the thermostat has opened up and the temperature has increased a few degrees past that point. This allows the radiator to passively cool, and saves energy. If you want to be sure, inspect the pins on both sides of the connection, make sure they are not damaged or loose or corroded. Then apply some dielectric grease to the connectors and secure the connection with electrical tape. BTW, did you install an OEM, TYC, Dorman (or other brand) fan? There are sometimes issues with the wiring being incorrect, or the connectors not holding securely together with aftermarket units.

 

So, currently I am leaning towards either:

 

A] an air bubble or a clog somewhere in the system as you have already mentioned. The easiest test for flow is simply to check the temperature of the hoses (radiator and heater core) as the engine warms up with MAX HEAT on.

B] a defective temperature blend door and/or actuator. Does the heat not come on in any position (PANEL, FLOOR, DEFROST, etc.) or just one of the positions?

C] a defective climate control module (EMTC/EATC).

D] plugged cabin air filter. May not be the case, but worth a check and change if not done recently. Also visually inspect the intake duct underneath the windshield cowling to make sure it's not clogged or blocked (leaves & bugs usually being the culprit here).

 

Coolant Flow Diagram, 3.5L

NOTE: Black arrows indicate hot, white arrows indicate cold.

Item Part Number Description
1 8C633 Lower degas bottle hose
2 8005 Radiator
3 8B273 Lower radiator hose
4 8B274 Upper radiator hose
5 6050 Cylinder head
6 6083 Cylinder head gasket
7 8A586 Thermostat housing
8 9N271 Heater inlet tube
9 9K461 Lower intake manifold
10 8501 Coolant pump
11 6010 Engine block
12 8W005 Upper degas bottle hose
13 18C553 Heater hose assembly
14 18B539 Heater core
15 8A080 Degas bottle

[Adi Barry]

Just to clarify, when I say the fans aren't working only when it cold starts, I mean the car will over heat because of this. No matter how hot the engine gets, they don't kick on until I've turned it off once (and usually I'll let it cool a bit before turning back on). Once I've turned it back on (after engines warmed), they kick on normally (either when hot or when I turn the AC On). I've double checked connections to be sure there's not a miss anywhere. But I do have 187k miles on the car, so it's very possible some parts are going out. I think it was Dorman. Everything looked alike from the unit I took out, including fan control module where fans plug into.

 

Thanks for the help. I'll try to test some of this stuff before I go to work today.

 

Also, heater blows air, just not hot unless the engines over heating (even then it doesn't always get hot). Doesn't matter where it's blowing (floor, panels, defrost, etc). It's the automatic climate control ( think?). No leaves or anything clogging the intake by the windshield.

[WWWPerfA_ZN0W]

Ah, I was hoping there was no overheating!!! Dorman is a good brand, so that should not be the issue. Sounds like there is a short somewhere, but, definitely, checking for presence of signal and voltage levels at the fan connection is in order. Check for frayed wiring, you may have open the harness to locate it. Check nearby grounds. Check battery with digital load tester if it comes to that. The fan is a variable speed unit, so it should come on at a "LOW" setting and a "HIGH" setting depending on load. When the fan comes on after the restart, does it come on at a high speed, i.e., is the fan essentially behaving as a one-speed unit?

 

Now that I look at the 2008 Edge brochure, automatic climate control was standard on the Limited.

[macbwt]

Just to clarify. Having been through this with another vehicle. Is there fluid flow? In other words is the water pump functioning? When you loose heat intermittently or all the time then this can be a very important symptom of a failed water pump and if it is intermittent then the pump blades are slipping on the shaft and once in a while catching and spinning. I would say verify the pump has not failed. If the pump is not pumping fluid as far as pressure then the fans may not activate and cool the radiator.

 

If this is the case then the fix is rather painful. The pump is internal to the engine and requires as they say some dis assembly.