RPMs dropping when turning defroster on full blast. PLEASE HELP!

[bigjoej956]

I noticed in the last week when my car is in drive at a red light and I have my defroster on full blast my RPMs will drop the car will shake a little and then the RPMs will go back up, then a little while later the same thing will happen the car has died once from this happening.
It does not do this when the car is moving or if its stoped and the heater is off or in park.
I did notice when driving with the defroster on full blast I had a smell like candles were just blown out. I also was siting in front of my house and had the car in drive with the defroster on full blast and turning it off and on and noticed after works either gas but probable oil on the ground mixed in with the rain by my excuast.


Does any one have any idea what the problem could be or how to fix it?

Im stating a new job after a long layoff and I really need my car running and being able to defrost because I am going to have to leave at 4am to go to work.

Please Help!

 

[my98nnj]

Clean or just replace the IAC valve.

 

[Turdle]

Yes, when defrost is selected the ac compressor is used to removed moisture from the air. The IAC valve will compensate for this and raise the idle a tad, unless it is dirty and sticking. The moisture from the tailpipe is probably normal.

 

[bigjoej956]

Clean or just replace the IAC valve.

Whats the best way to clean it out. Is there a easy way to see if it needs replacing?


Any other ideas what it could be?

 

[bigjoej956]

Bump

Any other ideas?

 

[Turdle]

It's a sticky.

http://www.explorerforum.com/forums/showthread.php?t=84220&highlight=iac+clean


Searching will usually get your answer once you know the terms to search for.

Basically, you want to make sure the plunger inside it is moving back and forth freely. grab the little bar inside with a needle nose pliers, move it back and forth until it is freed up, spraying cleaner also.

 

[bigjoej956]

It's a sticky.

http://www.explorerforum.com/forums/showthread.php?t=84220&highlight=iac+clean


Searching will usually get your answer once you know the terms to search for.

Basically, you want to make sure the plunger inside it is moving back and forth freely. grab the little bar inside with a needle nose pliers, move it back and forth until it is freed up, spraying cleaner also.

Thank you for the link. I took it out cleaned it let it dry but it back in but I am still having the same problems of rpms dropping. Should I just order a new valve? Is there any other thing I could try? Am I going to have to take it in to a shop?

Thanks for helping

 

[bigjoej956]

Could it be the air conditioning compressor?

 

[yavapaires]

Why do you needthe blower on "full blast" in thd first place? What happens when you haveit running at less than full speed? The "burning candle" smell is probably the resistor for the blower fan. I would try it at a lower speed and see what happens.

 

[bigjoej956]

Why do you needthe blower on "full blast" in thd first place? What happens when you haveit running at less than full speed? The "burning candle" smell is probably the resistor for the blower fan. I would try it at a lower speed and see what happens.

It has gotten worse to the point that even at the lowest level it still has the same problem.

 

[corkey]

check your voltage gauge, see if it drops too, it could be the battery is not fully charged, and the alternator is dragging down the whole engine,,
the draw on the battery with the radio , maybe the rear defrost and the fan on high might be the actual symptom of a bit bigger deal, ,

 

[bobflood]

It has gotten worse to the point that even at the lowest level it still has the same problem.

If problem goes away when the HVAC control is on a setting that does not use the AC, then problem is most likely the IAC valve or the AC compressor itself. If cleaning IAC valve didn't work, go ahead and replace it - lot less expensive than an AC compressor.

 

[koda2000]

does it also drop rpm when in a/c mode?

 

[bigjoej956]

does it also drop rpm when in a/c mode?

Yes the same thing happens with the ac on. I ordered a IAC Valve on Sunday $34 shipped so Ill give that a try if it dosent work I guess ill have to take it to a shop.