I wanted to share my issue about the ac/heater problem I had. One day in the spring (April-May) earlier this year my air conditioner stopped working on the 1st 3 settings (I have 4 total). I was able to get through the summer just fine without it. Basically, there was nothing blowing out of the vents unless I put it on speed 4. So that is how I would use the air conditioner and heater (now that it has gotten cold). Last Sunday on my way to church, speed 4 went out (not good with winter approaching). A friend helped me fix this problem since he had done it in the past on his car. It was a 2 step fix:

1) I had to replace the blower resistor. It had gone out. This is likely what caused #s 1-3 to go bad. We fixed it by taking off the glove box, and replacing the blower resistor. This cost $23.47 after tax at O'Reilly Auto Parts.

2) The fuse for the AC/heater went out, which caused it not to work on speed 4. Likely, I caused this with it always being on 4. This is a 30 amp fuse in the power distribution box under the hood (fuse 64 on my 2001 Focus). Cost for 2 was $4.26 at O'Reilly. Probably could have gotten them cheaper (this one has an LED that lights up..wasn't going for anything fancy, but was in a rush and didn't look around much.

I was thinking it was going to be a big fix, but wasn't at all...pretty simple. Grateful for my friend that knows cars!

It is really hot in the Dallas area right now. Many days of over 100 degree F in a row. Not the most convenient time for my AC to not work. I lost the blower in speeds 1,2,3 but the AC button would light and so would recirc. On speed 4 the blower would turn on but AC and Recirc would not.

I checked every fuse in the schematics, all were fine. I read the blog and changed the resistor block and the cabin filter. Little did I know, the blower motor was dying and blowing the resistor block blew so so quickly, I missed the fact, that I had stumbled on a symptom of the problem. I dropped the blower motor. It spun freely and did not make any unusual noise. I put it back and went back to the schematics. The problem was in one spot only. We tested the theory that it had to be something upstream of the resistor block causing the problem by purchasing the thermal cutoff from Radio Shack, You know the part that blows in the resistor block, the whole reason we have to replace it. I bought mine rated for 282 deg F at 10 amps, a higher rating than was originally on the car. We carefully replaced the thermal cutoff in the resistor block, Especially helpful to have a PC board building friend who could do it for me. We knew if it the blower would stay on at a higher fuse rating and work in all settings we were gonna have to replace the blower motor. Sure enough. I started the car with the switch on high. The AC button lit and so did the recirc. I could switch all the way down to the 1st level with success. Only after test driving the car for awhile did the resistor block blow again. I replaced the blower motor, re-paired the resistor block, put it all back together and yeah! AC!

I had a problem with my wife's 2001 Ford Focus. The heater fan would work but only in the highest (#4) position. The fan was off in the first three settings. After doing some research I discovered that one possible cause is a bad heater fan controller resistor. Additionally, the resistor can burn out as a result of blockage of the air intake for the climate control system.

Considering that I had just cleaned a small chipmunk's nest out of the inlet box the last time that I changed out the cabin air filter, I thought that this was the most likely problem. The cabin air intake is under the shroud between the hood and the windshield on the passenger side. There are three clips that are visible under the hood that need to be disengaged and two bullet clips that are hidden from view but can be located by two small circles on the surface of the plastic shroud. If your car is not equipped with a filter you can add one while cleaning the box by rooming the plastic screen in the box and replacing it with a pleated filter.

Changing the heater fan resistor is very easy and if you can change your oil you can most likely take on the job. The part (for my model # 3M5Z 18591 BA) is about $13 from a Ford dealership and a few dollars cheaper online.

The first thing is to remove the glove box by removing the three hex screws on the bottom of the hinge. Next three are three plastic clips that hold the kickcover on the area below the glove box. They are a little tricky to remove as they look like philips screws but do not back out when turned. The center needs to be removed with a small flat screwdriver and a pair of pliers then the outer ring can be removed.

The resistor is located to the left of the heater fan assembly. The unit is about 2 inches by 3 inches and mounted vertically. There is a single wiring clip attached with four wires running to the resistor assembly and a single philips screw holding the unit on. The reassembly is just a reverse of the disassembly.

The entire job with the cleaning of the air intake took me a little over one hour (half for the resistor and half for the air intake). The fan is working fine for now and I will give an update if there is any addition info.