[johntmcnally]

When I turn on the heat, it only blows hot air when I'm driving. If I'm not moving I don't feel heat coming out of the vents, so I know the heater core is fine. How can determine it is the blower motor or a resistor? I don't know much about this so any input would be great. If anyone knows of any writeups done on diagnosing this that would be great too. Thanks.

 

[Beachcruiser]

If you put the setting on defrost/warm/fan hi(not moving)...do you feel hot air coming out of the dash top vents?

IF not, then your blower fan isn't operating. First thing to check is the power connection to the backside of the fan. It's located in the engine bay, under the battery tray on the passenger side firewall. Plugs onto the tab on backside of blower motor.

 

[Que89YJ]

Its getting colder here. You need to get that thing fixed! Do you hear the blower spinning? Can you get a meter and see what voltage you have at the motor? Where are you at in Metro?

 

[Mike Romain]

The blower motor switch bypasses the resistor pack when on high so if no high, I would check the fuse first. Second I put power direct to the motor from the battery to see if the motor spins up. As mentioned, the power plug is under the battery tray.
I have also seen the wire break/rot at the resistor pack where the wire from the switch routes so the power from the switch just stops there.

 

[johntmcnally]

I do not feel hot air when I'm not moving, however, when I'm driving I can get defrost. I'm in Berkley. I do not hear the blower spinning, so I think it's definitely the fan is not working, I will troubleshoot tomorrow and let you guys know. Thanks!

 

[Matt The Hammer]

The air blowing will not change if driving or not. Normally. The YJ heater system is uber simple.

Check the blower fuse.

Sent from my rotary phone using JeepForum

 

[Que89YJ]

You are in Berkley you are on my way home from work. I would be glad to lend a hand. PM me.

 

[Mike Romain]

The air blowing will not change if driving or not. Normally. The YJ heater system is uber simple.

Check the blower fuse.

Sent from my rotary phone using JeepForum

Mine sure changes. I get forced air through mine when driving with the fan off and the air on.

 

[dancytron]

Mine sure changes. I get forced air through mine when driving with the fan off and the air on.

Yeah, me too.

 

[Que89YJ]

Mine does too. The my vacuum check valve is bad.

 

[johntmcnally]

So after taking off the battery tray to get a better look at the blower motor where the electrical connection is supposed to be, I found no place for a connection. Took pictures but unfortunately they won't load. What I assume to be the blower motor is a small ylinder about 3-1/2 inches in diameter about 4-5 inches long? Also found a short black hose about three inches long sitting about 5 inches below it on the firewall that didn't lead to anything, is that just some kind of bleeder hose? Thanks for the help.

 

[Que89YJ]

That's the blower motor. Sending you my email do I can post the pics for you.

 

[Que89YJ]

Here are the pics you sent. The motor is the newer one with the wires on the inside under the dash. The tube is the drain tube for your HVAV plenum.
Look at the pics on this thread for a better idea of how it works:

http://www.jeepforum.com/forum/f12/heater-core-219329/

Check power at the blower switch first:

http://www.jeepforum.com/forum/f12/heater-fan-does-not-work-887570/

 

[Que89YJ]

This is your pic of your blower

 

[johntmcnally]

Is this where I'm supposed to be checking for power connection? It seems like this is supposed to be my resistor, right?

 

[Que89YJ]

The blower switch first on your control. I can't see the pic but the resistor block is a square. Right side.

 

[johntmcnally]

Hey guys, I replaced the resistor and my heat now works flawlessly! Thanks for help

 

[mike134]

Fun tip: Some people use a piece of cardboard/wood to block a portion of the radiator in the really cold months to get more heat out! Just watch the engine temperature to make sure you don't block off too much.

 

[silleYJ]

I am having a similar problem as well....
I have power to my blower motor under the battery box
I have ohm'ed out my resistor and it checks to be good I will probably go ahead and replace it anyway
I have replaced and ohm'ed out my fuse and it checked to be good
I connected direct power from my battery to my blower motor power under the battery box and it clicked once and never turned on.....does this mean my motor is out?

What do I need to check/do next????

 

[Que89YJ]

You put direct power to the blower and it didn't work the blower its bad.