1994mustangman

how come when i turn my defroster on it scearms and bogs the motor down but i can turn it on floor and it dont.. any advice thanks

jeb

paintslinga2010

From what ive been told the defrost activates the a/c compressor which is what causes the engine to bog. The a/c somehow dries the air i think making the windows un fog faster.

My car does this same thing. hopefully someone can chime in and tell us why this happens and what can be done to remedy it. Im hoping its fixable.

mjr46

when in defrost mod a/c compressor engauges and the a/c works in conjunction with the heater to dehumidify the air

paintslinga2010

should the compressor cause it to bog down though and idle lower? I know the a/c robs power but i feel like mine is a little on the extreme side. Maybe my compressor is on the way out.

1994mustangman

damn i hope the compressor aint going out that will break the bank lol.. but really i dont think its the cause b/c i think i can turn my a/c on not sure havent done since it started

mjr46

compressor puts a load on the motor so idle will drop briefly buy IAC controls idle, at wot a/c compressor is disengauged

1994mustangman

will some just tell me what they think it is plz

mjr46

It's your azzometer that needs calibrating......wtf do you think??? do you think anyone can accurately diagnosis such a prob without going for a ride?? It could be alot of things, that prob needs to have a professional sit in the seat to interpret the prob, When people call my shop wanting such a diagnosis over the phone with such a prob, I tell them, that one I need to go for a ride to accurately diagnose it....but if you want some homework, take the belt off and see if there is excessive drag on the compressor pulley and or clutch assembly

1994mustangman

lol ok sry.. but from ur experince what does it sound like 2 u

mjr46

from my experience it seems normal, if you had read the thread in it's entirety, you'd understand what we were explaining, in the defrost mode as I already "told" you, the a/c compressor is engauged to dehumidify the heated air, and when compressor is engauged it creates a load on the motor and robs power........however, in the floor mode the compressor is not engauged and occupant air is not dehumidified, hence why the windows will steam up, therefore , conclusion is you have no issue , system is operating as designed, you just fail to understand description and operation of it, next time don't be so obstinate and try and comprehend what was being stated, this is the only explanation I can give you, unless I were able to go for a ride and feel if there is a prob , which I doubt.