Hey guys, I just started having a problem with my A/C. It was running fine and then after going to dinner with the wife, the A/C blower won't come on. The compressor is working, the lines are cold, but not air from the vents! I have checked the manual for fuses, but can't find a fuse for the blower.I lifted the hood and tapped on the blower, still nothing. I can feel a tiny bit of cold air coming from the vents, but not enough to cool my truck. Help please! I live in Texas on the coast and its almost 100 degrees already. Any ideas?

Thanks
Gordeaux

 

It sounds like your four wheel drive is broken. But how can that be you ask?? The ESOF (electronic shift on the fly) 4wd system you have by my guesstimate, has either (a) a leaking air line or (b) a burned out vacuum pump or pump fuse. See, the vacuum not only pulls a vacuum for your front hubs, but also it uses air to actuate how your trucks HVAC (heating, ventilation, and a/c) system provides air. I'm also willing to bet that you only have air coming from the defrost vents- the trucks safety default setting. So check the fuse for your air pump, if that's good, then check the pump itselft- it's right next to the "vacuum box" on top of the passenger fenderwell in the engine compartment- you'll see some small hoses running from the pump to the box and some other fittings that go to your hubs. Let us know if that fixes your problem. If not we'll figure something else out. Oh yeah, BTW, welcome to FTE!! Hang out long enough and you'll be surprised whatcha learn here!!

 

Danny ! Good write up ! Don't you think the blower motor would run even with a vacc leak ???? I thought just the vents themselves were operated on vacc ????

 

Russ I think your right the blower fan will still work on all speeds with a vac leak. Gordeaux I would look into the blower motor resistor. It is mounted on the Ac box under the hood right behind the accumulator.

 

Sorry I didn't catch that- yeah, the blower will still work, so if it's not then yeah, Costa's right. Also, if the vac system is still functional, if you listen carefully, you can hear the vents changing position from under the dash after you change from like floor to dash.

 

If you have a vacuum leak then your ventilation will default to the defrost position. If you have a leak in the 4x4 ESOF system, then you will get defrost when you go from 2wd to 4wd or back. After a few minutes your ventilation system will go back to normal (the solenoid shuts blocking the ESOF system from the rest of the vacuum system).

If you're not getting any airflow it could be:

1. Blown fuses for the blower
2. Dead blower motor
3. Dead resistor bank

If your fuses are good, then I would go for the motor first. The resistor bank will usually fail for a single setting (either not blow at a certain speed or only blow at a certain speed). A blower motor failure will just not work.

I am not a mechanic, but I had a similar circumstance on my last truck ('97 F150). Ventilation just stopped. Turned out to be a bad motor.

You can get the motor and resistor bank from a junkyard (to save cost). If you do get a new motor and try to put it in yourself, be sure to align the blower wheel so it doesn't rub. There is not much clearance (at least there wasn't on my F-150) and I had to adjust it a couple of times before it didn't rub (just do a spin test to see if you hear/feel rubbing).

I hope this helps...

 

Does it work on high? High speed bypasses the resistor and goes directly to ground to give max speed. Check the power to the blower motor (brwn/org wire). If hot, try grounding the org/blk wire and see if the blower motor runs. If a test light comes on when probing the org/blk wire (with harness plugged in), you have a ground problem. It could be a bad ground thru the blower resistor or switch. If everything checks out, the blower motor is probably out.