Convert Digital to Standard Analog HVAC Contols

[Mountaineer302]

We have a 2001 Mercury Mountaineer with the electronic digital HVAC controls. It has been problematic since we got this truck a few months ago. Other than this it is in great condition. It replaced a 1998 that was totalled. The 98 has the standard HVAC controls. What all is involved with switching from digital to analog?

 

[1998Exp]

We have a 2001 Mercury Mountaineer with the electronic digital HVAC controls. It has been problematic since we got this truck a few months ago. Other than this it is in great condition. It replaced a 1998 that was totalled. The 98 has the standard HVAC controls. What all is envolved with switching from digital to analog?

Probably more than fixing the existing EATC system. What exactly is wrong with it?

 

[Mountaineer302]

It will not turn the blower fan on most of the time and is all around flakey. I would much rather have traditional control like in my F150 and like our older 98 Mounty had.

 

[1998Exp]

Remove the blower and try turning it by hand. If you feel resistance or wobbling, it's time for a replacement. If OK, apply 12V directly from the battery and see what happens. If all is fine, it's probably the speed controller (aka "resistor"). Sorry, I don't know how to diagnose "all around flakey".

 

[koda2000]

The blower module may be your problem (assuming the blower motor is okay). This is a common problem with the automatic HVAC control models. The blower module is the digital equivalent to a blower ballast resistor (controlling fan speed) and is located just below and to the right of the blower motor on the passenger side of the firewall in the engine compartment.

I believe someone here converted to the manual HVAC controls, but as I recall it's quite involved to do so.

 

[Mountaineer302]

Is there some sort of minimum engine temp before it will run heat?

Also, we have had issues on wamer days when it will not run the fan for the AC to work.

 

[1998Exp]

Is there some sort of minimum engine temp before it will run heat?

Also, we have had issues on wamer days when it will not run the fan for the AC to work.

In AUTO mode, to prevent blowing cold air when heating is needed, it won't engage the blower until the engine warms up. However (assuming everything is working properly), you can turn it on manually with the little wheel on the right. If manual doesn't work either, check the blower and the controller, as I suggested earlier.

 

[Mountaineer302]

The blower motor is operating smoothly and quietly when it works. It is not bound up and spins freely. I was thinking it was the resistor, but didn't realize that it went by a different name for a digitally controlled system.

 

[koda2000]

Is there some sort of minimum engine temp before it will run heat?

Also, we have had issues on wamer days when it will not run the fan for the AC to work.

There is no min engine temp required for the fan to run, but the fan is supposed to automatically select an appropriate blower fan speed based on the temp selected, the cabin temp and the temp of the water in the cooling system. if you select 90 degrees of heat and the engine coolant is at 35 degrees, the blower fan will blow slower until the coolant temp reaches something near or above 90 degrees, then it will automatically speed up. If you select MAX A/C the the display will show 60 degrees and the blower will always start blowing on high speed. You can always override the automatic fan speed with the thumb wheel on the EATC (Electronic Automatic Temperature Control) panel, or by using the steering wheel mounted FAN control (if so equipped).

Personally I do not like the digital/automatic HVAC controls and would rather have the manual controls, but the better optioned Mountaineers and Explorers always came with the EATC.

I believe your blower fan issues (heat and A/C) are related to your blower motor or blower module and not the EATC controls.

 

[Mountaineer302]

I really appreciate your input. I am inclined to agree with your thoughts here. I will investigate a bit further.