waldersha

So just as it says, I'm having issues with getting any airflow from the vents. The blower motor is running strong on all settings, and I am not having any issues with changing from defrost to dash vents, etc.

The hoses coming from the heater core in the engine compartment are both warm to the touch. The ones that go to the evaporator though are ice cold, as is the evaporator itself. It actually has ice forming on it.

In the cab, one side of the heater stuff under the dash is warm to the touch, but the other is cold and even had some frost forming on it. There is almost no air coming out of the vents, but what does come out is warm as it has always been.

The other day there was snow built up on the intake and I think it sucked some in because it was snowing inside the truck for a few seconds. Then last night it was doing the same thing with the no airflow, so I was messing around with it and it started working again. There seems to be a catch in the warm/cold selector from time to time, and yesterday there was a big one.

Not sure where to start, but no defrost where there is freezing rain isn't fun. Any help is greatly appreciated!

klx650a2

Did it just start blowing low volume? It sounds like there might be stuff (leaves, etc) in your hvac system blocking the flow of air. My truck sits outside all the time in the snow and ice (right now -25) and I never have any issues like that.

waldersha

Yes, just started. In fact, this morning it was fine, but last night it did the same thing. It almost sounds like the air is going back out the intake.

waldersha

Ok, a bit more info. I just pulled the blower out and there were a couple of leaves in there, but nothing that would cause a plug. I reached up in there as far as I could and couldn't find anything either. I did feel to the immediate left though whatever it is that is so cold. It had frost built up all over it in there, but I could only reach a couple of inches before hitting that. Seems like the air should be going straight up to the vents then?

waldersha

First thing this morning I go out and fire it up, air is screaming out of the vents. The further I drove and the closer that it got to operating temp, the less air came out. At a loss here, anybody have any ideas?

nkennedy

Sounds like the Blend/mix door is not working right. Check the plug on the bottom of the black box that holds all the HVAC stuff. That's the door controller.

waldersha

Ok, you lost me a little bit here. Check the plug for what? Electrical plug? The only wires I see going to it are to the blower motor and to the resistor.

Junk Man

Air flow on my 2000 is vacuum controlled. Temp is electronically controlled. There is a whole section on diagnosing & troubleshooting in the FSM. On cars I have messed with, vacuum lines crack at the connections or the mode door wears at the hinge & hangs in 1 position or another. You might see how easy it is to get to the vacuum lines. If a pita, track down a diagram before you end up taking extra things apart. It's usually not complicated, just time consuming.

waldersha

Thanks for the reply. everything switches correctly between the different modes, I can hear the door when I go from defrost to vents to floor to recirc, and the air that comes out is warm like usual, but there just isn't very much coming out.

Is is normal for the lines from the evaporator to have frost on them while the heater is running? Like I said the lines to the heater core from the engine are both equally warm to the touch (hot enough to not want to hold on to) so I don't think that part is plugged, but it doesn't make sense that after it warms up it cuts the airflow off. I would think that it would be the other way around, but with the box inside getting so cold on one half I wonder if it's not freezing itself off?

JeepManIowa

I'd be curious to see what the resolution to this is. Because I have a similar experience with mine. However, mine is an 06.

I can hear the blower motor running real strong, just doesn't feel like it at the vents.

Hopefully this weekend I can spend some time on this.

Later.

infidel

Wonder if you are low on refrigerant causing the A/C coil to freeze up blocking flow.
Ice on the compressor points to this also.

dieselman2300

I was going to say the same thing infidel said. If your low on freon your evaporator will freeze up.
another thing to try is pull the a/c compressor fuse, and see if it stops freezing up.

Busboy

Last two guys are probably right. Unplug the compressor and see if it still does it.

waldersha

Ok, I'll give that a shot and let you know how it turns out. The A/C compressor is supposed to run when the defrost is on right?

Busboy

Yes!
You could just unplug the low press sw on the accumulator/drier that should also cut out the compressor.