2014 mirage DE heater failure

[Eggman]

From the Coolant flush thread

A few weeks ago I picked up forum member pawpaw's original heater core. Today I ran an experiment to see what might clean it out. Have a look:

It's an old bottle I had sitting around waiting to be used:


Notice the warning about aluminum:


First flush on the right, half Parsons' Sudsy Ammonia (wish it wasn't sudsy...) and half water on the left. The right hand jar was dumped after two hours of soaking in the half & half solution:


Left bottle is the second flush:


First flush sediment:


Second flush sediment:


Third bottle of clean solution prepared for another soak & flush:




Third flush using a bottle brush to remove more contamination (disregard the blue material found in the brush bristles):


Third flush sediment:


I'm currently soaking a fourth batch of half sudsy ammonia and water. Thanks foama for the suggestion.

[foama]

When my heater core was failing, I tried out all sorts of chemicals, mainly lye, all with a high PH value. Lye is what dissolves aluminium, grease, silicone residue. Anyway, nothing really helped, so I replaced the heater core without having to remove the dash.

See the dedicated thread:

https://mirageforum.com/forum/showth...-core-with-pix

I took the bad heater core apart and noticed:

1.) The numerous inlet slits for the hot water channels are extremely small, thin and roughly rectangular shaped. The clearance for water entering a slit opening is only about as wide as a piece of letter paper is thick! Thus a tiny amount of blockage material is enough to cause a full blockage of any particular slit.

2.) The core has numerous of these slits, and the the slits on the passenger side (right side) were most affected.

3.) Contrary to what was initially thought, the slits were blocked by lime scale. Lime scale can only be introduced to the cooling system by tap water. Since I was the first owner and had never used tap water, it must have been in manufacturing.

4.) To remove lime scale (calcium) you need an acid, a lye is useless. Thankfully a mild acid will not eat up the aluminium.
A weak solution of lime scale remover disolved the blockages in almost no time. It would have revived the old heater core, but it was cut up for finding the causes.

[scottmarsc]

Thanks, guys for all the input and responses. We are currently using this car for a toad (towed) vehicle behind our motorhome, and have travelled almost 2000 miles this past week- heater worked just fine before we left, but now blows only cold air with the temp set all the way up to 86 degrees. A/C compressor engages and blows cooler air when the temp is set low enough for it to kick on. I'm not sure if there is something in the climate control switch/module that may have failed causing the heater to not blow air through the heater coils. Everything else seems to be functioning just fine.

[Fummins]

In your first post you said the blend door works fine. Maybe start over from there.
-Can you actually see/hear the hot/cold blend door moving?
-Can you feel any difference in air temps between cold and hot?(it can take a few seconds for blend door to move).
-Does revving up the engine slightly(1200+rpm) and holding it there increase air temps? If so then your heater core is probably plugged.

[scottmarsc]

Thanks guys! May have found the issue- drove the car 60-70 mph for over half an hour today and have some warm air coming from the vents at the end of the trip. Maybe the thermostat has failed (open) and I just haven't run the car long/far enough to get the engine up to temp. Will replace the thermostat (cheap/easy) and write back with the results.

[Fummins]

I have no idea at this point if there's even a problem. There are lots of unanswered questions.

If the engine isn't warming up then the green thermometer light on the cluster would likely stay lit the entire time. It goes out once the engine is up to temp. Usually...Sometimes it may not even turn on if it's warm out?

[Top_Fuel]

I think that green temperature light on the instrument panel goes out when the coolant reaches 137 degrees F. If that's wrong, I'm sure I'll get pummeled for posting fake news.

Spend $30 on a bluetooth OBDII reader that you can pair with a phone app like Torque Pro. Then you can see your actual coolant temperature. I would do that first. If your coolant temp is 160+ and you don't have heat, something else is going on.

Oh...make sure your coolant level isn't low. These cars don't have low coolant level warning lights...and low coolant levels will mess with your heat output.

If you decide to toss a thermostat in it anyway, be careful. THIS guy broke a bolt when swapping a thermostat in his 2014. He was also chasing a low heat problem. Too bad he never posted if the new thermostat fixed his problem.

[mohammad]

There is also a DTC code that throws the check engine light if it thinks the thermostat is stuck open.