Blower slows/stops when accelerating

On my 1990 Jeep Wagoneer Limited (XJ/Renix) When I have my heat or A/C on and accelerate, my blower slows or comes to a complete stop. I was told this was actually a gas saving feature on some older vehicles. Is that true and/or is this normal? The car also has California emissions, don't know if that makes any difference.

Someone is blowing smoke up your tailpipe.

You have a vacuum system problem, probably a bad line to the vacuum reservoir or the reservoir itself is bad. Reservoir is located under the passenger side front bumper--yeah, true rocket science. You can relocate the reservoir into the engine compartment, I put mine under the coolant tank shelf.

Are you sure your blower is stopping? The usual problem with vacuum leaks is that the distribution door moves so that it starts blowing out of the defroster only. The blower fan speed actually should not change. The only "economy/performance" thing some vehicles have is a AC compressor shut off at full throttle. This was usually controlled by a vacuum switch to cut the AC compressor (not the blower fan) off to put more power to the ground (rear wheels).

Are you sure the motor is stopping, or is it just changing where its coming from? Say; You start with heat to the floor, and as you accelerate, it switches from floor to defrost?
If this is the case, its still a vacuum leak, and I have not found mine yet.

winterbeater said:

Are you sure your blower is stopping? The usual problem with vacuum leaks is that the distribution door moves so that it starts blowing out of the defroster only. The blower fan speed actually should not change. The only "economy/performance" thing some vehicles have is a AC compressor shut off at full throttle. This was usually controlled by a vacuum switch to cut the AC compressor (not the blower fan) off to put more power to the ground (rear wheels).

Click to expand...

Actually no, I guess I am not positive the blower speed is changing. I'm pretty much using the "hand held up to the vent method" of seeing how much it blows. It could be a vacuum problem, my vacuum reservoir was initially broken and I just replaced it. If this is the case, would it be because at higher speeds I am pulling more of a vacuum at the engine which results in not having enough vacuum to hold the blend door in the proper position? Just trying to picture how it could be malfunctioning in my head.

I did not check to see if the air is shifting from the floor to defrost, I will try that on the way home tonight. I definitely don't think I am getting the "full" blower force out of my vents - when I first start the engine it is very strong for a second or two then I have less pressure.

winterbeater beat me to it! check the defrost - I think thats default...
Hopefully someone has a good solution to this one...

Overflow, your reasoning is correct -- 99% chance this is your problem, particularly since you just worked on the vacuum system. Solution is to follow the vacuum line from the point where it exits the firewall to the reservoir and find the break. Common place is around the battery or of course, where connected to the reservoir bottle. Reservoirs have a check valve (or at least they used to) which, if defective, can cause the same problem.

Pelican said:

Overflow, your reasoning is correct -- 99% chance this is your problem, particularly since you just worked on the vacuum system. Solution is to follow the vacuum line from the point where it exits the firewall to the reservoir and find the break. Common place is around the battery or of course, where connected to the reservoir bottle. Reservoirs have a check valve (or at least they used to) which, if defective, can cause the same problem.

Click to expand...

So I tested this on the way home and yep, you guys were right; when I was giving it gas it was switching to defroster! I will trace the vacuum line tomorrow morning, I am guessing this is probably why I am getting crappy gas mileage and rough idle as well.

The original Wagoneer vacuum reservoir had two inlets on each end. The replacement reservoir I got only had one inlet. I simply "T'd" the other 3 connections into this one inlet, would this cause a problem?

That is exactly what I did--no problems.