No heating

[GR11M]

It's the first time I've used the heating in a long while as I didn't drive it last winter. Since it last worked I have done a fair amount of work on the car which has included refitting of all the coolant hoses and a coolant refill, a front mounted oil cooler fitted and a new thermostat.

There's air flow from the vents but it stays cold and never heats up even when on full. I drove it through the summer, the A/C was cold and it wasn't overheating which should rule out low coolant or air in the system and a thermostat stuck closed. The coolant, oil and cylinder head temps have stayed the same during the summer and winter.

I've got a list of possible causes, some I can already rule out, the others will have to wait until the snow melts.

https://www.wheelsjoint.com/ford-mustang-heater-not-working-causes-and-diagnosis/

Any further advice would be appreciated.

Sponsored

 

[raptor17GT]

Mmm I could be sarky and say you the select the heater option in the Mach-E build sheet but it wouldn't be helpful.

Going by what you've listed above my money would be an airlock in the heater matrix / pipework as on most cars it's the top most coolant circuit and the last to get coolant during a refill and mostly likely to hold air as a result.
Can you reach any of the pipes for the heater matrix and confirm they get hot as the coolant heats up, should be quite noticeable and will indicate if they have coolant flowing through them.
Also the radiator pipes at the front, you can 'burp' the coolant system by squeezing the pipe into the radiator and this'll help force any air out of the system.
Not sure on the Mustang but does the heater matrix have a bleed valve to help get air out? Cars with this valve you can attach a small flexible pipe to this bleed nipple and vent air out as the engine is running.
You could with a cold engine maybe jack the front of the car up and try bleeding the system again with the expansion cap off, air should be forced out through the open cap as it's now the highest point of the circuit but watch the engine temperature gauge closely as it can jump real quick when it's warming up when the cap is off. Also watch for coolant overflow.

Whatever route you go always have the heater temperature set to max so there is maximum coolant flow through the heater matrix.

Good luck !

 

[Slopoke]

It seems as though there can only be two problems. The first, is that the heater core is not getting coolant to it, or it's blocked. The second is that the heat is controlled by a temperature door. It works by modulating the amount of air going through the heater core.

The service manual states to check the inlet hose of the heater and see if it's hot. If it's not bleed the coolant system. If it is hot, measure the temp of the heater core outlet hose. If it's cold, the core is blocked.

If the temperature of the outlet hose from the heater is good, the temperature door is either not getting power, or it's failed.

Good luck and let us know what the fix was.

 

[sk47]

Hello; I am not familiar with the heater hose arrangement on the Mustang so this may not be paractical. On most cars the coolant flows thru the heater core all the time. There is not a valve to shut off the coolant.
What I can do on most vehicles is to locate the heater hoses. As an engine warms up the heater hoses also warm up. If both heater hoses get warm then coolant is flowing through the heater core.
How the heat gets into the interior of most new cars is by doors that open and close. In warm weather you turn the heat off. Doors around the heater core shunt the heat to the outside of the vehicle. (Out the cowling in front of the windshield on some i am familiar with) During cold weather the doors open or close to flow the heat into the interior. May be the doors are not opening/closing properly. I would try running in all the operating positions for a bit including the recirculating part. May be lack of use has stuck the doors a bit.

I figure the engine has a thermostat of some sort. May be that is stuck open. Some thermostats are designed to fail in the open position.

Good luck

 

[GR11M]

Checking the in and outlets was going to be my first job, how easy is it to get to get access to it, I've seen people removing their entire dash to replace it ?

Mmm I could be sarky and say you the select the heater option in the Mach-E build sheet but it wouldn't be helpful.

touché

 

[raptor17GT]

You should be able to check the pipes to the heater from within the engine bay without removing too much but I have no idea where the pipes run / route so I'm gonna tap out here but hope you get it sorted cheaply and quickly.

 

[Slopoke]

Checking the in and outlets was going to be my first job, how easy is it to get to get access to it, I've seen people removing their entire dash to replace it ?

The pic below shows the hoses. Looks simple enough.

 

[sk47]

Hello; For what it is worth there are things can be tried before pulling the dash to get at a heater core. If the core is not leaking ought to be able to get coolant flowing.
One thing is to take the heater hoses loose in the engine bay and blow some compressed air thru. However, it is not clear how the core gets plugged up in a closed system.

If the heater hoses do not get warm then may have air in the system although that you ran it during the summer without a problem should have purged the air out.

 

[dirtwarrior]

Check your coolant level. It is most likely low

 

[GR11M]

OK so first run today, if these are the coolant in and outlets to the heater core, both were hot to touch, so it's not that.

 

[Slopoke]

OK so first run today, if these are the coolant in and outlets to the heater core, both were hot to touch, so it's not that.

If that's the case, it's the temperature door not working.

 

[Slopoke]

The link below is for a 2015 Mustang. It should apply to your car as well. Good luck.

 

[sk47]

If that's the case, it's the temperature door not working.

Hello; This makes sense. The coolant is always flowing thru the heater core with doors and ductwork directing the air flow. Question is how the heat/AC and vent doors are operated. Some use basic cables to operate these doors. Some use vacuum motors to open and close the doors. Had a Ford F-150 which used vacuum motors. The individual motors being controlled by a manifold on the dash.
Good luck.

 

[sk47]

The link below is for a 2015 Mustang. It should apply to your car as well. Good luck.

Hello; Good post. Looks like the doors are controlled with electric motors and gears.

 

[Gregs24]

OK so first run today, if these are the coolant in and outlets to the heater core, both were hot to touch, so it's not that.

Had similar on a Mondeo once and the climate control had got confused - resetting fixed it. maybe worth disconnecting the battery for a bit to see if that fixes it - would be a lot easier if it did!

Sponsored