why when in gear idling and you turn ac on or heater on does it rough idle

Sounds like your idle air valve is not compensating for extra load from AC compressor be it a control issue or a physical problem with idle air valve it self. When you say heater do you mean defrost because AC generally works on defrost to dehumidify

when i say heater i mean no matter weather i put the heater on for heat or i put ac to cool.the engine goes to a rough idle? turn the control knob to off and the engine runs smooth when idling in gear???

Is the heater fan on when HVAC controls are turned on? Just double check that AC isn't turning on, open hood and watch compressor clutch. Verify it's not engaging . Possible fan lost could drag down alternator and put load on engine

i will check if the fan is turning on !cooling and heating works fine when turned on never checked fan?will do this now!get back to you and thanks.

checked fan.all is working well.when fan comes on ,rough idling?when fan goes off because i turn knob to off.smooth idle?would that make problem idle control valveonly???

I have a similar issue, I have a 2001 4dr Ford Escort 2.0, I found out that when I have the ac, heater fan off, ac fan to head n heater fan to feet, it won't revive every 5 seconds on a stop or red light. However, it will revive every 5 seconds for a second or two when on ac, max ac, heater fan to head n feet and window and feet. What could be causing reviving every 5 seconds lasting 1-2 seconds when in those ac or heater settings?

I have pretty much the same thing with our 2004 Escape V6 XLT. When we are at at stop light if the heater fan is on even low and the engine fan turns on it drops the idle to about 400 RPM's...I have check and made sure the AC is off and set everything to the off positions. When it drop's the idle low i turn off the heater and the idle goes back up where it belongs. Whats up I tested the Alternator and The battery all good.

My 2000 Ford Escort started with a similar problem three (3) years ago. The engine develops a rough idle when I come to a stop, if the A/C is on, it gets worst. I have replaced the Idle Control Valve, Idle Control Sensor, MAS Sensor, Motor/Transmission Mounts, Oxygen Sensors and cleaned the Engine Air Control Valve. The car continues with the same problem! It runs great otherwise, so I have decided to ignore the rough idle at stops and minimize it by shifting to neutral.

My 2002 ZX2 does exact same thing and do the same living in vegas at a light put it in neutral there has got to be a answer have had 3 different ICS had intake manifold gasket replaced now has seem to idle ruff with headlights and heater on not defrost but put at 1200 rpm smooths right out or put in neutral. turned idle up but that turns on check engine light.????

Yes, I even tried turning up the idle which made the engine run better when I came to a stop, but then the check engine light came on. As I said, I am not worrying about it any more, I just shift to neutral when I come to a red light and the a/c is on.

Iv read alot of the same problems im having on my 02 trail blazer. I had changed my alternator about 3 weeks ago and this happens. I dont remeber a low idle befor the old alternator went out. Plus i see every one has the dame problem but i didnt see in here one answer how to fix

Low voltage from battery to accessories probably a dirty or bad connections.when turning on lights or heater fan its pulling power from alternator instead of from battery. Putting to much load on alternator in turn causing motor to idle to low and or killing motor. Hope this helps

This also could be the blower motor resistor especially of your fan speed only works on usually the higher speeds...this i herd can be a pain to replace because they can be behind the dash and i hate taking apart the dash i always break some plastic clip...my 2012 ford escape at the end of summer stopped producing cold air but figured needed a charge and it was September so decided to wait as i am in Maryland and can deal with that in spring...but then 1.2.3 fan speed stopped and only 4 work...the heat and ac always made the headlights dim and dash lights dim when the compressor kicked on but just at first...the heat now does this but about a month ago at idle it stalled the engine...never while running only on idle hot or cold engine its random...but had became more and more frequent...my car stalls when heats on and im at idle...so this sucks. I have 150,000 miles and this car is my life blood to my wife and job which i just got laid off from until March. . I want to do all this maintenance and do not know where to start or what it needs most....as this is not a serious issue i want to do a tune up..flush the systems...and just do a bunch or preventing maintenance...sorry for the personal story i am in auto zone passing and on my phone pissing off the workers as i walk in laps around on my phone lol...but can not find anything directly saying this 100% would make it stall just a bunch of words that sounds like it could like how if the blower resistor goes bad it can need more power and uses more power to run since always on high speed

Have an 01 zx2 compressor runs in the off, vent ,basically any position but the modes it should run in. Any ideas

IDK