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UPDATE: Overheats When Climate Control Blowing Warm Air


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Gswan
Novice

Jan 22, 2017, 2:43 PM

Post #1 of 6 (439 views)
UPDATE: Overheats When Climate Control Blowing Warm Air Sign In

2006 Mercury Mountaineer Premier
4.6 V-8
153,000 miles


2006 Mercury Mountaineer overheating when heater or AC blowing hot air. When the heat is on it starts to overheat. Once I turn the heat completely off, it cools back down. I turned on the AC and it was fine. Then, with the AC on I turned the temperature up to 90. It blowed the hot air but then started to overheat. When the AC is on and set to blow cold air, it's fine. So, it's only happening when the temp is turned up to get heat whether it's in heat mode or AC mode. Any ideas?
Autozone pulled these codes... P0446 P0196 P0506 P2004 P2005


(This post was edited by Gswan on Feb 11, 2017, 5:24 PM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jan 22, 2017, 3:32 PM

Post #2 of 6 (427 views)
Re: Overheats When Climate Control Blowing Warm Air Sign In

Really doesn't make too much sense because hot water is constantly flowing through the heater core even when the HVAC is turned off.

How is the coolant level and condition? Does it start to over heat at idle, cruising, or both?

If it is low, have you checked for leaks?


None of those code relate to your issue.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jan 22, 2017, 3:38 PM)


Gswan
Novice

Jan 22, 2017, 4:52 PM

Post #3 of 6 (415 views)
Re: Overheats When Climate Control Blowing Warm Air Sign In

I know it makes absolutely no sense! We just bought it a couple of weeks ago and haven't had it checked yet.
Coolant is full and looks good. We have been watching for any sign of leaks and there are none.
It can idle with the heat on forever and the temp gauge holds steady at normal. It only happens when cruising. When it happens, I turn the heat completely off and within a minute the temp gauge is back down to normal.

The temp gauge went all the way up and caused the red warning light to come on but there was no steam or anything coming from the engine.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jan 22, 2017, 5:43 PM

Post #4 of 6 (404 views)
Re: Overheats When Climate Control Blowing Warm Air Sign In

The engine computer monitors the cylinder head temperature and sends that information to the instrument cluster. If the engine was actually overheating, the engine computer would enter a fail mode strategy and start cutting out cylinders which makes it run bad to cool the engine down. Also when it overheats, it will set trouble code P1285 cylinder head over temp.

You did state it seemed like it was sputtering under load around 45mph? Depending on the type of misfire it might not set a trouble code. Those kinds of misfires are usually a problem with ignition coils or plugs. I've heard of ignition coil issues causing the wacky things to happen to the electronics. Maybe the misfire/ignition issue is causing the PCM to get wacky with the temperature gauge.

It would be interesting to see if the coolant is actually overheating. We'd use a inferred thermometer and measure the cylinder head temp at the base of the sensor to see if it corresponds with the actual cylinder head temp reading using a scan tool.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Gswan
Novice

Jan 31, 2017, 4:39 AM

Post #5 of 6 (358 views)
Re: Overheats When Climate Control Blowing Warm Air Sign In

It's in the shop now. Will let you know what they find the cause to be.


Gswan
Novice

Feb 11, 2017, 5:23 PM

Post #6 of 6 (334 views)
Re: Overheats When Climate Control Blowing Warm Air Sign In

Wanted to get back to you to let you know what they did to fix the issues.

The sputtering was spark plugs. They did a complete tune-up and it's now running great.
The overheating issue when the climate control/heat was on ended up being a bad thermostat plus it was missing the fan shroud.






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