Intermittent No Cabin Heat Problem

[HMayes]

Hi Folks,

I have a 2013 Explorer Limited with a little over 150k on it (I’ve owned it since a tad over 100k). The issue I’m having is the car will intermittently not deliver heat. The blower seems to be working just fine. I’m wondering where to start with diagnosing.

Here’s what I know so far:

- Coolant was a little low. Maybe an inch or so in the overflow. I’m honestly not sure the last time I’ve checked it.
- Reproducing it is difficult, but mostly, it seems to deliver no heat at idle. If I’m in park and rev the engine, sometimes it will get warm, sometimes not.
- It will usually deliver heat when driving at highway speeds, but not always.
- The (electronic) gauge cluster shows the heat gauge right in the middle. I haven’t seen it get any higher than this, so I don’t think it’s overheating.
- I have not checked the oil yet (it’s my wife’s car, so I don’t drive it often). But i will check for milky color and report back.

Assuming the oil looks okay, where do i start with diagnosing? I know it could be heater core, thermostat, etc. I’m hoping it’s not the water pump, but I don’t want to be dumb about it either. I know it’s getting up there in miles. Any advice appreciated. Thank you!

 

[peterk9]

You can't really go by the gauge as it likely won't go higher until you have an actual engine failure. Here is another thread that is similar but unfortunately no solution was posted. Possible heating issue? 2013 XLT
I don't know if it could be a blend door issue since you are getting heat at times. Is the issue the same regardless of the HVAC position for airflow?

Peter

 

[HMayes]

You can't really go by the gauge as it likely won't go higher until you have an actual engine failure. Here is another thread that is similar but unfortunately no solution was posted. Possible heating issue? 2013 XLT
I don't know if it could be a blend door issue since you are getting heat at times. Is the issue the same regardless of the HVAC position for airflow?

Peter

Thank you for the reply. I read the thread you linked to (thank you), but I’m still not sure where to start with diagnosing. I’ve done some more testing and it seems the heat comes on pretty consistently if you get the car to 55+ mph. Alternatively if i shift to manual mode and delay the up shift to higher rpm ranges it will delivery heat. Seems to be tied pretty consistently to higher engine RPMs. High RPMs will give you heat, lower RPMs will not.

Thinking through this I’m assuming either heater core or water pump? Thoughts on where to go with diagnosing? I’m going to check hoses to heater core today.

 

[HMayes]

You can't really go by the gauge as it likely won't go higher until you have an actual engine failure. Here is another thread that is similar but unfortunately no solution was posted. Possible heating issue? 2013 XLT
I don't know if it could be a blend door issue since you are getting heat at times. Is the issue the same regardless of the HVAC position for airflow?

Peter

Okay i did some digging and have some new info. I went to check the coolant overflow and it was dry. Drove it up to my shop and parked it and there was a little in the overflow (maybe an inch). So i think i definitely have a coolant leak since i topped it up maybe 2 weeks ago.

With engine running and heat on full blast, I added coolant (50/50 Motorcraft) to the reservoir and squeezed the upper radiator tube to try to burp it. Then I checked the heater core lines. The bottom one was hot, top one was cold. So I’m wondering if i also have a plugged heater core? After that i had a helper rev the engine and per usual the heat got hot. I also noticed some air bubbles coming up into the overflow, so we revved the engine up and down for a few minutes to try to get all the air out. Now i have heat even at idle, though not quite as warm as it “should” be, maybe more air? Now I’m wondering if heater core is fine and it was just air bound due to low coolant level and air getting into the system.

Anyone who knows more than me care to chime in and let me know where to start looking for a coolant leak? I don’t think it’s the water pump. Engine oil looks perfectly fine to me, no milky appearance. Also i watched a YouTube video (FordTechMakuLoco) and he said on the 3.5s the other spot the water pump leaks is out the double seal onto the top of the alternator. While i can’t see that perfectly well on my engine, i did shine a light down there and didn’t see any signs of coolant or previously getting wet.

Thanks in advance.

 

[dudefish]

I'm having a very similar problem, hoping I can get some troubleshooting and advice for my 2013 Limited.

I recently had the Ex at the dealership for some routine maintenance, and they did a coolant replacement. She has about 130,000 miles, so yeah, that was due. Shortly after, I started having problems with no cabin heat. At first, I assumed it was a faulty blend door and didn't connect it to the coolant replacement.

Over time, though, I noticed that if I keep it in a lower gear and run around at higher rpms (like 3000 or more), I get heat. Plenty of it. Blend door clearly works, too, because I can get the air to blow cooler or warmer. Similar phenomenon applies to the rear heat, although it blows cool/warm separately from the front, I'm guessing it has a separate heater core and blend door but I don't know.

So it seems pretty clear now that when they filled my Ex with coolant, the dealership didn't fill or burp it properly and I'm not getting hot coolant to the heater cores consistently.

Is there a quick and easy way to burp the system? I really don't want to go back to the dealership, because it's such a doggone hassle.

 

[Mbrooks420]

You’ve got an air bubble. Either raise the drivers side as high as you can, start the truck and add coolant as it drops. You can also raise the front end, but it has to be a little higher.

 

[dudefish]

Saving this for later

 

[03WIExplorerLtd]

You’ve got an air bubble. Either raise the drivers side as high as you can, start the truck and add coolant as it drops. You can also raise the front end, but it has to be a little higher.

Doesn't leaving cap open for half an hour work? Engine running

 

[Mbrooks420]

No.

 

[dudefish]

So, I checked my coolant reservoir, COLD, this morning. It was empty. Yeah. I think I'm getting warm. Will get a gallon of 50/50 this afternoon and fill it, burp it, and then see where I am.

 

[Barry Trobaugh]

So, I checked my coolant reservoir, COLD, this morning. It was empty. Yeah. I think I'm getting warm. Will get a gallon of 50/50 this afternoon and fill it, burp it, and then see where I am.

Like a baby. it needs to BURP.

 

[03WIExplorerLtd]

So, I checked my coolant reservoir, COLD, this morning. It was empty. Yeah. I think I'm getting warm. Will get a gallon of 50/50 this afternoon and fill it, burp it, and then see where I am.

That's a problem. Check you oil....

 

[peterk9]

So, I checked my coolant reservoir, COLD, this morning. It was empty. Yeah. I think I'm getting warm. Will get a gallon of 50/50 this afternoon and fill it, burp it, and then see where I am.

I agree with 03WIExplorerLtd that it could be a problem, especially if the coolant leaked into the engine which a leaking water pump can do.
Hopefully, that isn't the case.

Peter

 

[dudefish]

I’ll check to make sure I didn’t lose coolant into the lube system, but my heat is fixed! Added about 1/2 gallon of 50/50 to the reservoir and followed the burp procedure outlined in the video. Heat!

 

[03WIExplorerLtd]

I’ll check to make sure I didn’t lose coolant into the lube system, but my heat is fixed! Added about 1/2 gallon of 50/50 to the reservoir and followed the burp procedure outlined in the video. Heat!

Watch like a hawk. Something doesn't seem right. That's alot to add....