Heater/AC blower intermittant - 1996 F150, 4.6 4WD
#1
Heater/AC blower intermittant - 1996 F150, 4.6 4WD
the heater AC/blower works now and then. I noticed that when it stops, if I back off the accelerator, it kicks in...I suspect some kind of vacuum leak. At the same time, today, I also notices a stumble/hesitation when accelerating in neutral....could they be related ?
#3
Hi Guys,
I thought I answered a post similar to these a few days ago, but in any case you should be looking for a good sized vacuum leak. The reasoning behind this is; with the throttle butterfly near closed position maximum vacuum is available to the reservoir and accessories. When the throttle is opened vacuum drops and the reservoir is supposed to provide momentary vacuum to the accessories and the drop is not noticed. If the leak is large enough which in this case it is, you are noticing the result of insufficient vacuum. Leaks could be cracked vacuum hose somewhere, hose came off, or possibly a cracked vacuum reservoir which has become quite common these days. I would suggest starting with the previous suggestions and you might get lucky and find it right away. You could try pinching different vacuum hoses and look for an immediate but quick duration change in engine idle speed.
Sometimes you can use a plastic bottle with a small hole in the cap and squirt water around the areas you suspect and you should notice a definite difference in idle speed even for a second or two.
I thought I answered a post similar to these a few days ago, but in any case you should be looking for a good sized vacuum leak. The reasoning behind this is; with the throttle butterfly near closed position maximum vacuum is available to the reservoir and accessories. When the throttle is opened vacuum drops and the reservoir is supposed to provide momentary vacuum to the accessories and the drop is not noticed. If the leak is large enough which in this case it is, you are noticing the result of insufficient vacuum. Leaks could be cracked vacuum hose somewhere, hose came off, or possibly a cracked vacuum reservoir which has become quite common these days. I would suggest starting with the previous suggestions and you might get lucky and find it right away. You could try pinching different vacuum hoses and look for an immediate but quick duration change in engine idle speed.
Sometimes you can use a plastic bottle with a small hole in the cap and squirt water around the areas you suspect and you should notice a definite difference in idle speed even for a second or two.
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