Boosting the heater fan output

'91 XJ, without AC

Is there a mod or upgrade to increase the output of the heater fan? A stronger/faster motor? A fan wheel that moves more air?

I'd like to get a good, forceful blast of air from the heater.

Any advice appreciated.

Are you sure your current system is operating correctly? A damaged vacuum line can cause the air to blow through the defrost vents or perhaps the blower motor needs to be replaced, etc.

Yeah ... it's all operating properly and correctly. I would just like to get more air ... I'd like to feel it really push on my hand when I put it down there.

All the vacuum lines are in good shape ... when I run the heater, it only comes out the bottom, when set to vent, it only comes out the vent, and when set to defrost, it only comes out on the window.

I'm willing to replace the motor, but I don't think that will make much difference. I've replaced motors on other vehicles in the past and didn't see any real improvement.

Any mods to help get more air?

I wonder if this would work:

http://www.youtube.com/watch?v=UkKk7qSaKJY

This guy is putting rare earth magnets to the outside of the motor to increase the magnetic field, causing the motor to run faster and/or stronger. This will also probably cause the motor to draw more current.

Sorry, a double post

Thanks for that link ... at this point, I just want to get more air out of my current fan. The air comes out very hot, and the cab heats up just fine, but I'd like to get more air.

Thanks.

I've been pretty satisifed with the heater setups in the various XJ's I've had, as long as they were in good working order, and I'm one who does like a blast of hot air out of the vents like you. If you're sure the vacuum actuators are working right and air is coming out where it's supposed to according to the vent settings and piping under the dash.... Here's what I would do...

I'm assuming your blower resistor is working right, (the fan works on all settings, not just high). Check the voltage output at the blower motor connector under the hood with a voltmeter with the fan on high. Post what you're getting and we could compare.

Take the blower motor out and spin it by hand and see if there's any resistance or gumminess. I know you said it's in good shape, but you might be surprised. Replacing the whole assembly is cheap. I don't know of any "upgraded" ones that move more air, but you could ask at the parts counter and see.

Upgrade the wiring to the blower motor itself. This might be tricky, and you'll probably not be able to retain the factory switch or resistor, so you'll have a blower that only works on high and runs off a toggle switch... but you could run a relay and a direct hot lead from the battery and probably get a little extra "oomph" out of the blower.

Finally, you can take the blower motor into a place that specializes in electric motors and see what your options are. We have a place here in town called "Auto Electric Rebuilders" but they also do electric motors in tools and such as well. They might be able to build you a hot rod blower motor... keep in mind that if you do this, you may HAVE to run the upgraded wiring I talked about in the previous paragraph since the factory wiring may not be able to handle the draw.

Hope this helps.

Ok ... I found the problem.

I took out the blower motor, and the rubber gasket between the motor flange and the firewall was pushed aside at one point and wasn't sealing properly. There was a big gap on one side of the motor. Probably happened at the factory. So some of the air pressure from the blower wheel was actually going into the engine compartment.

I reinstalled it with the gasket seated properly, and the air pressure in the cab is much better now ... big difference.

Also ... the voltage at the blower motor with the engine running and the blower motor running on high setting was 12.5 volts. The voltage at the connector with the blower motor disconnected, but the switch still set to high, was 14.1 volts. So ... there was a 1.6 volt drop when the motor was connected and running. Is this normal?

And one other thing ... when I listen very carefully in the engine compartment with the blower motor running on low, I can hear the beginnings of a "chirping" sound, which indicates the bearings are going bad. I'm sure this is the original blower motor, so I guess it's time to replace the motor.

Can anyone recommend a good brand? I know AC/Delco makes good products ... anybody experienced their blowers?

Thanks.

check your ignition switch wiring and the wiring at the HVAC switch behind the panel.

usually burnt and nasty. big imrpovements to be had by cleaning it up and replacing terminals.

The fan switch wiring runs through the ignition switch?

Any write-ups on accessing ignition wires? I guess it would involve going into the steering column.

does the fan turn off when you turn off the ignition? Yes, everything in the interior goes through the ignition switch, that's why the terminals get melted and nasty.

the switch is located midway down the column. It's a 30 minute job to get at it. Well documented here.

I'd also make sure to check the connector at the back of the HVAC control panel, also has a habit of being melted and nasty.

87manche said:

Yes, everything in the interior goes through the ignition switch, that's why the terminals get melted and nasty.

the switch is located midway down the column. It's a 30 minute job to get at it. Well documented here.

I'd also make sure to check the connector at the back of the HVAC control panel, also has a habit of being melted and nasty.

Click to expand...

Ok ... thanks for the info ... Do I need to access the ignition switch itself ... or just a wiring plug somewhere else in the vehicle?

it's below the tumbler on the top of the steering column. Under the dash. It's no where near where you put the key in.

it's well documented on here with pictures and such. search oem tech for ignition switch replacement.

Just so you know Ac/delco does not make anything anymore,your buying a name on a box they sub out to their spec and put in their box.For those of you running Delco filters cut one apart, you will never use one again.Dont get me wrong they have ok products except oil filters which is made by champ "think purolator and other cheap filters " same filter company.I've been working parts for ten years i'll sell you whatever you want,just my opinion.

Just a quick thought: You can get your full battery voltage with a relay and not have to mess with standing on your head to access the ignition switch. More later if interested.

The last blower motor I got was a VDO which was part of Siemens for a time. Now owned by Continental AG I believe. I think they still manufacture the blowers (Rock Auto) but I can't vouch for current quality. At least they are German and not Chinese.

you know how it "feels" colder when you turn a box fan higher? well, if you want heat, a lower speed will allow the air to sit on the core longer causing it to get warmer, faster.Also, a higher air speed will cause the core to cool off faster which in turn makes it harder to heat. just stick with what you have. start the jeep turn the heat on 2 and go back in the house for a little. or get a remote start.