View Full Version : Rough Idle when heater is on

11-18-2006, 03:16 PM
Is that normal ? when the heater is off it idles fine, but when I turn the heater on it starts idling rough, you can really feel a difference, just wanting to see if thats normal, and if its not does anyone know what is wrong with it ?

11-18-2006, 05:17 PM
more thank likely you have a vacuum leak when ur heater turns on... so find it and fix it!

11-19-2006, 12:23 PM
~~~~, that doesnt sound very fun, what lines would I check that would cause a vacuum leak when the heater is on ?

11-20-2006, 12:12 AM
When you turn the heater on, do you turn it to "Panel" or do you turn it to defrost or floor or one of the other ones? Turning it on to panel works like opening the vents, which means it doesn't engage the A/C compressor. The other ones all engage the compressor, so what you may be feeling is the compressor running. It's not abnormal to notice slight idle fluctuations when the compressor is engaging and disengaging, but having the car noticeably bog when it engages could be signs of a failing compressor. Try running the heat in "Panel" and see what it does.

11-20-2006, 10:40 AM
it droppes the idle about 2 or 3 hundred I think, I normaly run at about 700 in idle, but when it is on it is about 500 roughly, but I never tried turning on just the vent as apposed to the defrost or floor, I will try that, thanks