Jeep Heat wasn't working, now is?

In My Humble Opinion
1

Earlier in the summer we were out late at night and the temperature was unseasonably cool. I turned on my 2016 Jeep Wrangler’s heat, but got only cold air. I tried again every so often, but only got cold air.

I actually picked up a thermostat but kept forgetting to do anything. I did check my radiator coolant level and it was full. I squeezed hoses, seeing if I could work air out, but nothing happened.

Last night we were out and it was cold (48 degrees). My gf reached for the heat and turned it on. Just as I was preparing to explain why there was no heat, there was heat!!
I have heat again today.

Any thoughts/ideas on why I could have no heat for ~2-3 months and now suddenly I have heat back?

2

Maybe the stat froze up in a position to allow engine cooling but not compartment heating. Then with the cool weather, the metal contracted and unfroze the stat and now you have heat.

3

Doubtful.
All modern engines that I have seen have the heater loop independent of the engine cooling loop.The water for the heater comes off of a bypass hose from the water pump, and is “behind” the thermostat, so the water will be as hot as the engine is at any time.

My guess is - broken blend door, or blend door control.

4

Jeep? My guess is rust in the heater core. Depending on how it breaks apart/floats around sometimes it is clogged and sometimes it is not.

5

Could be something as simple as there was some air somewhere in your coolant system when you tried the heat and none came out, and in the time since then air got burped out by parking on a hill, cornering, something else, and now the air issue has fixed itself.

6

Yes, but if the thermostat is stuck open, the engine may never get up to temperature, so it doesn’t matter where the line for the heater is. If the engine is cold, then there won’t be any heat.

7

Even with the thermostat stuck open, the water temperature will be at least “warm.” And, it’s an obvious failure, if the vehicle has a temperature gauge.

8

If the vehicle has been properly maintained I doubt it’s a plugged heater core but certainly not impossible. My guess is the same as another poster, a blend door not working in the heater case. Perhaps binding up or a vacuum control may have a pinhole in it.

When it was malfunctioning did the hoses feel hot to the touch?

9

It’s a Jeep, Man! C’mon, you’ve had many as I recall. Mystery Shit is a Feature!

I don’t even diagnose stuff anymore. I just give it a day or two. Caroline forgives me for whatever I did wrong, and goes back to normal.

10

OP, I’m on the Jeep Garage Forum and you’ll get good answers there. After joining JG I joined a couple of Jeep groups on Facebook. Quick and accurate answers are there too.

Good luck.

ETA — your model is the JK (mine is a diesel WK2). Those are the subforums and FB groups you want, if you’re on FB.

11

:laughing:

I mis-read this as “Jeep Garbage Forum”

Seems legit.

12

I wish I’d noted that, but I never raised the hood unless the engine was cold. I’ll try to poke around this weekend.

13

Every time this sort of thing has happened to me it was the thermostat. It’s the cheapest, fastest, and easiest place to start.

14

Are you quite certain that the A/C was turned off? All the suggested problems with the engine’s cooling system are very unlikely.

15

Definitely. This went on for months. I felt upper and lower hoses yesterday, both were hot to the touch.

I still have heat, but the air blowing is warm, maybe even very warm, but not hot.

Getting access to the actuator/blend door area is difficult. I’ll either need to remove the driver’s seat or train a capuchin.

16

Do you have a cabin air filter that needs to be replaced? Usually located behind the glove box.

Made a big difference in air flow for my daughter’s 2002 Toyota Avalon that by the appearance of the filter it had not been changed in awhile.

17

Some things not even a monkey will do.