Weird A/C problem

[techieman33]

Tonight I went to get some parts from a guy to help fix up Turdles mountaineer, his wife has a 98 mountaineer so we were talking about them, common problems and such. So now to the problem her A/C blows coldish when on max a/c but when on regular a/c it's blowing hot. Any thoughts? If it was the blend door I wouldn't think it would blow cold air at all.

 

[almond900]

sorry I can`t help but if you figure it out let me know my 98 explorer is the same way.

 

[TheJackal]

It's likely to be the blend door, actually. The heater core is bypassed in Max A/C mode, but is open in regular A/C mode.

 

[techieman33]

Ok thanks

 

[ranger7ltr]

I would think in non-max a/c the outside air being pulled in...

It's likely to be the blend door, actually. The heater core is bypassed in Max A/C mode, but is open in regular A/C mode.

And the heater core is still bypassed unless the blend door has a problem...

Do you notice outside odors in your truck when the non-max a/c position is being used? I started smelling exhaust or freshly cut grass when in max a/c [ which is all the time for me] and knew my vents temps were not as good but the refrigerant system was working real hard to cool the inside.. I had a piece of foam come loose from the outside air door and it was stopping the door from closing...Now my vent temps are back under 40 F even when it is hot as hell outside...

You can tell if the heat is coming from the heater by pinching off one of the heater lines temporarily and see if the air temps drop or stay down...Who knows you may be getting heat from a blend door malfunctioning and outside air mixing with the recirculating colled air...

 

[rizzjc]

You can actually check the heater core bypass when in the different modes to see what state it's in. I am having similar, but not easily reproducible issues right now with mine, but recently fixed another explorer where the bypass had been installed backwards.