2005 XLT - No AC in defrost mode?

[rocky top buzz]

Hello all, I have read this board for many years (My wife and I have a 1999 and 2005 Explorer), but now I need some advice.

I first noticed a strange problem, the AC is not cutting on in Defrost mode. I switch over and the amber AC light is off, and I cannot get it to turn on. Anyone else had this problem?

I am having a more immediate problem though. The AC is not cold at all on the drivers side. The passengers side and the rear seats (separate climate for rear) do seem to be plenty cold, and I checked today and the refrigerany level is fine, right at 55 PSI. I added a little more but am thinking now I better siphon some of that back off.

When I flip between regular and Max AC I do hear the noise pick up so I assume the recirculate door is operating fine. But I absolutely cook when I'm driving that car! But the passengers all seem to be ok.

Has anyone had a similar issue? I hate to take it to someone without at least myself knowing first what it is, and if I might fix it.

 

[Javadog123]

AC won't work in defrost cause it will fog up your window. not sure about your other problem.

 

[rocky top buzz]

I'm pretty sure you have that backwards. The AC is what prevents the window from fogging up.

Anyone else?

 

[Javadog123]

Just checked mine this morning. AC turns off in defrost. Defrost pulls in outside air. Try use the heater next time you need to defrost your window. Works like a charm.

 

[BrianDye]

Yea you use heat to defrost the windows...

 

[joecrna]

However, I know of no madern vehicle that does not use the "AC" compressor to dehumidify the air when on defrost so the windows do not fog even more. I guess some more of use should go out to see if this indeed how the Explorer system works.

 

[rocky top buzz]

Yes, I can't say I am 100% certain on this, but I thought that the AC light used to always come on for defrost? Plus sometimes you need to defrost when it's warm outside.

I assumed this was a symptom of the lack of cool air on the drivers side, but perhaps not? Did anyone else check their 02-05 to see if the AC light is on in defrost, or if you can turn it on?

 

[joecrna]

Actually look at the compressor and see if the clutch engages when going from vent to defrost. After all, a light could be burned out. What we are really interested in is does the AC compressor run when the defrost is on.

 

[rocky top buzz]

good point, but I know the amber AC bulb isn't burned out because it is on in AC and Max AC modes.

 

[rocky top buzz]

Just in case anyone finds this thread years from now, I took the car to the mechanic and the problem is I was low on refrigerant. I had a leak in the o ring where the high-side line meets the condenser. The guys I took it to say I need a new high side line and a new condenser ($750!) so I've taken the car for a second opinion.

But the cause of the temperature differential is definitely due to low refrigerant.

 

[BigRondo]

You are correct about low refrigerant causing a temp differential: http://www.explorerforum.com/forums/showthread.php?t=323725

My AC light does not come on in defrost mode. Pushing the button will not activate the light. Running the defroster with the temp selector set to cold will utilize the AC for defogging purposes.

From my owners manual:

(Defrost)-Distributes outside air through the windshield defroster
ducts. It can be used to clear ice or fog from the windshield. If the
outside temperature is about 43°F (6°C) or higher, the air conditioner
will automatically dehumidify the air to reduce fogging. (Note that the
A/C indicator does not illuminate when this mode is selected.) For
added customer comfort, the system will allow some airflow through
the floor ducts in this mode.

Hope this helps out!