Blower motor turns off on accelleration

[ribob]

Any thoughts on this? I have the a/c on cruising down the highway and i step on the gas to pass a truck, all of sudden my blower motor stops working.
i pass the truck and release the pedal and like magic, it come back on! I tried it a few more times and sure enough, it happened every time. It is a 1997 EB edition with climate control (which isnt on when it happens, just on high) and a 5.0 liter.
Thanks

 

[RSudar1]

Mine does the same thing, did you ever find out what was wrong?

 

[1998Exp]

Are you sure it's the blower? What you are describing sounds like an air duct door closing and diverting the air somewhere else. Those doors are operated by vacuum motors. When you step on the accelerator the throttle opens fully and the vacuum drops. There is a "vacuum reservoir" (somewhere under the passenger side fender) - a canister which is kept empty of air during normal operation and provides the needed suction when manifold vacuum drops. I would look there first: perhaps there is a hole in the reservoir, or perhaps it's a malfunction of the check valve that connects it. Another possibility is a defective seal in the climate control unit itself. Didn't hear of that case in 2nd gen Explorers, but it's quite common in Crown Vics - which use the same system.

 

[RSudar1]

Are you sure it's the blower? What you are describing sounds like an air duct door closing and diverting the air somewhere else. Those doors are operated by vacuum motors. When you step on the accelerator the throttle opens fully and the vacuum drops. There is a "vacuum reservoir" (somewhere under the passenger side fender) - a canister which is kept empty of air during normal operation and provides the needed suction when manifold vacuum drops. I would look there first: perhaps there is a hole in the reservoir, or perhaps it's a malfunction of the check valve that connects it. Another possibility is a defective seal in the climate control unit itself. Didn't hear of that case in 2nd gen Explorers, but it's quite common in Crown Vics - which use the same system.

You are really close.... Actually, You are close to describing the issue. The blower works great (on all speeds) until I'm pulling my boat and have to put a huge load on the vehicle. Then the blower cuts out (on high, haven't really noticed it at any other speeds) until I lower the RPM's. It works a little better when I set it at in house AC air as apposed to High AC air. But once I let off the gas, it blows harder. I think it also shoots out the defrost when this happens. Not quite sure what to make of this symptom. Thanks for your input! You ROCK! I know this original post was 7 years ago. How the heck did you find this? I wasn't expecting a response so quickly! LOL

 

[1998Exp]

I believe that defrost is the default, in absence of vacuum applied to any door motor. In addition to what I wrote yesterday, also look for loose vacuum connections behind the EATC controller.
How did I find a seven-year old post? Because you brought it back to life yesterday...

 

[Turdle]

I think it is normal, there is a WOT ( Wide open throttle) relay which turns off max ac at load.

I think this is controlled by the throttle position sensor output voltage. You might check to see if your throttle position sensor is hitting 4.5v before the throttle is wide open.

 

[1998Exp]

I think it is normal, there is a WOT ( Wide open throttle) relay which turns off max ac at load.

I think this is controlled by the throttle position sensor output voltage. You might check to see if your throttle position sensor is hitting 4.5v before the throttle is wide open.

Turdle, are you saying that WOT condition affects anything beyond disconnecting the compressor clutch? Hard to see how it would affect duct doors, or why if the purpose is to remove the extra load from the engine.

 

[Turdle]

You might be experiencing a combination of the WOT relay and loss of vacuum. As mentioned before, when vacuum goes real low the vents switch to defrost.
Find the vacuum reservoir,mounted on the inside of the passenger inner fenderwell, and remove it from it's mount so you can shake it to see if it has filled with condensation (water). If it has, you can shake it all out with enough time.

Also, check the 2 hard vacuum lines running along the inner fenderwell going to the reservoir. They sometime will crack, or get heat damage which clogs them.

 

[Justinwht]

Reading the first post in this thread, the WOT relay was first thing to come to mind. Different manuals call the WOT relay by different names -- took me awhile to figure that out.

HELPFUL HINT ... The WOT relay on '96 Explorer is same relay as fuel pump relay right next to it. Truck wouldn't start so swapped relays to get me going.